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tpu 2735 teletext processor edition jan. 13, 1993 6251-312-4e itt semiconductors
tpu 2735 2 contents page section title 4 1. introduction 5 2. functional description 6 3. specifications 6 3.1. outline dimensions 6 3.2. pin connections 6 3.2.1. 40-pin dil plastic package 7 3.2.2. 44-pin plcc package 8 3.3. pin descriptions 10 3.4. pin circuits 11 3.5. electrical characteristics 11 3.5.1. absolute maximum ratings 11 3.5.2. recommended operating conditions 13 3.5.3. characteristics of the digital section 13 3.5.4. characteristics, rgb interface 14 3.5.5. characteristics of the external ram 15 4. various operation modes of the tpu 2735 15 4.1. the menu mode 15 4.2. teletext display without interlaced lines 15 4.3. the effect of errors in the transmission of teletext data 15 4.3.1. errors in the hamming-code protected data 15 4.3.2. errors in data with parity check 15 4.4. multipage conflict situation 16 5. ram organization 17 6. controlling the tpu 2735 with the ccu 2030, ccu 2050 or ccu 2070 17 6.1. the address commands 18 6.2. the data transfer command 18 6.3. the status test command 18 6.4. the im bus hardware test/configuration register 19 7. the control registers of register chain 2 19 7.1. the page request registers, r-prx 20 7.2. the page selection register, r-ps 20 7.3. the subcode register, r-sc 21 7.4. the display selection register, r-ds 21 7.5. the data acquisition control register, r-dac 22 7.6. the status indicator register, r-si 23 7.7. the display control registers, r-dc1 to r-dc6 27 7.8. the memory control register, r-mc 28 8. the control registers of register chain 1 28 8.1. the page identification register, r-pi 28 8.2. the control bit register 1, r-cb1 28 8.3. the control bit register 2, r-cb2 28 8.4. the control bit register 3, r-cb3 29 8.5. the row flag register, r-rfx 29 8.6. the timing of the register chains
tpu 2735 3 contents, continued page section title 29 9. two ways to select a page for display 29 10. reset of the tpu 2735 teletext processor 30 11. application notes 33 12. description of the im bus
tpu 2735 4 teletext processor for level 1 teletext note: if not otherwise designated the pin numbers men- tioned refer to the 40-pin dil package. 1. introduction the tpu 2735 is specified to handle level-1-teletext in- formation (in germany: videotext) as it is transmitted to- day by the tv broadcast stations in great britain, ger- many and other european countries. the tpu 2735 is part of the digit 2000 digital tv system and works in conjunction with the other vlsi circuits and processors of this system. this makes the teletext adapter de- signed with the tpu 2735 very simple and economic (see fig. 11). the tpu 2735 is an n-channel vlsi mos circuit, housed in a 40-pin dil plastic package and contains on a single silicon chip the following functions: one-chip solution of the teletext processing (except for external ram) ghost compensation to eliminate the effects of ghost pictures due to reflections reduced access time is provided for the teletext pages by receiving and storing up to eight pages in one go up to 32 stored pages automatic language-dependent character selection switchover facility pal/ntsc/d2mac full level one features (flof) support level 1.5 spanish teletext support largely compatible to the tpu 2732/33 mcu 2600 main clock gen. tpu 2735 teletext processor vcu 2133 or if amplifier tuner 64 kbit 256 kbit d ram vcu 2134 saa 1250 ir trans mitter to cr t teletext adapter 64 3 fig. 11: teletext application block diagram ccu 20xx or ccu 3000 central control unit tba 2800 ir preamplifier keyboard
tpu 2735 5 2. functional description the tpu 2735 whose block diagram is shown in fig. 21, operates according to a rigid timing determined by the vertical cycle of the tv receiver. the data acquisition period starts at line 7 with pal or line 10 with ntsc and ends at line 22 with pal or line 21 with ntsc. during this period, the input data is processed by a ghost filter which is able to compensate reflections with short delay time of 0 to 0.8 m s for pal or 0 to 1 m s for ntsc. in the d2mac mode the acquisition is active from line 1 to 22 and line 313 to 334. in the data acquisition unit the teletext information is synchronized and identified. a comparator preselects the pages with page numbers that are requested by the ccu 2000 or ccu 3000 central control unit and loads them into the ram. to eliminate speed problems of the external dynamic ram, the data is buffered in an inter- nal ram buffer (fig. 21). the comparator contained in the data acquisition unit decides into which sector of the dram the data is stored. the display period starts at line 48 with pal or line 50 with ntsc and ends at line 286 with pal or line 242 with ntsc. the display control unit selects one of the stored eight pages for display. the 8-bit character words are transformed into a 6 x 10 dot matrix with pal or 6 x 8 dot matrix with ntsc by a character generator (rom) of 96 programmed characters and are displayed in 24 rows of 40 characters each. optionally, 25 rows can be dis- played in pal/d2mac. different character sets are available for eight languages under ccu or transmitter control, the required character set being selected auto- matically by the control bits c 12 to c 14 of row 0 of the teletext page displayed. every tenth line with pal or every eighth line with ntsc a new teletext row is loaded from the dram into the ram buffer. when the ram is not accessed by the tpu 2735, the memory control re- freshes the memory and handles ccu requests for ram access. via the im bus the ccu can access all ram locations and controls the tpu 2735 by loading the appropriate registers in the ram, so that the tpu 2735 can be used to display text from other sources. the tpu 2735 can display a list of contents of the stored eight pages (menu) all by itself.the tpu 2735 can use either one 64 kx1 bit dynamic ram or one 256 kx1 bit dynamic ram. so, ram capacity is flexible to store up to 32 pages. the drams can be standard types (see section 3.). tpu 2735 ram buffer memory data bus 1 data bus 2 start address bus data acquisition unit ghost compensation control unit display control unit and character gen. central timing and control im bus interface data 27 28 29 30 35 16 15 14 31 36 13 12 11 9 8 7 6 32 33 34 5 4 3 2 1 40 39 10 17 18 19 21 22 23 24 25 26 a0 a7 a8 r g b bl. h v res. dsd im bus fm 8 88 8 6 v1 v6 gnd bl. r g b 38 d2 data fig. 21: block diagram of the tpu 2735 ras cas r/w v sup
tpu 2735 6 3. specifications 3.1. outline dimensions fig. 31: tpu 2735 in 40-pin dil package weight approx. 6 g, dimensions in mm 0.45 +0.1 10 x 1.27 = 12.7 0.1 10 x 1.27 = 12.7 0.1 1.27 0.1 1.2 x 45 2.4 2.4 1.2 x 45 17.4 +0.25 140 39 29 28 18 17 7 6 2 17.4+0.25 0.254 1.9 1.5 4.05 4.75 0.15 0.711 1.27 0.1 16.5 0.1 16.5 0.1 0.1 fig. 32: tpu 2735 in 44-pin plcc package, weight approx. 2.2 g, dimensions in mm 3.2. pin connections 3.2.1. 40-pin dil plastic package 1. v3 video input 2 v4 video input 3 v5 video input 4 v6 video input (msb) 5 gnd 6 r output 7 g output 8 b output 9 fast blanking output 10 fast blanking input 11 horizontal blanking pulse input/d2sync input 12 vertical blanking pulse input 13 reset input 14 im bus data input/output 15 im bus ident input 16 im bus clock input 17 a0 ram address output 18 a1 ram address output
tpu 2735 7 19 a2 ram address output 20 n.c. 21 a3 ram address output 22 a4 ram address output 23 a5 ram address output 24 a6 ram address output 25 a7 ram address output 26 a8 ram address output 27 data input/output 28 read/write output 29 cas output 30 ras output 31 skew data input 32 b input 33 g input 34 r input 35 v sup 36 f m main clock input 37 n.c. 38 d2data input 39 v1 video input (lsb) 40 v2 video input 3.2.2. 44-pin plcc package 1 v2 video input 2 leave vacant 3 v3 video input 4 v4 video input 5 v5 video input 6 v6 video input (msb) 7 gnd 8 r output 9 g output 10 b output 11 fast blanking output 12 fast blanking input 13 horizontal blanking pulse input / d2sync input 14 reset input 15 im bus data input/output 16 im bus ident input 17 im bus clock input 18 a0 ram address output 19 leave vacant 20 leave vacant 21 a1 ram address output 22 a2 ram address output 23 vertical blanking pulse input 24 a3 ram address output 25 a4 ram address output 26 a5 ram address output 27 a6 ram address output 28 a7 ram address output 29 a8 ram address output 30 data input/output 31 read/write output 32 cas output 33 ras output 34 skew data input 35 b input 36 g input 37 r input 38 gnd 39 vsup 40 f m main clock input 41 leave vacant 42 d2 data input 43 leave vacant 44 v1 video input (lsb)
tpu 2735 8 3.3. pin descriptions (for 40-pin dil package) pin 1 to 4 and 39, 40 video inputs v1 to v6 (fig. 34) inputs for the digitized composite video signal from the vcu 213x or vad 2150. the video signal uses a parallel gray code, input v6 is the most significant bit (msb). pin 5 ground, 0 v pins 6 to 9 r, g, b and fast blanking outputs (fig. 36 and 37) the r, g and b outputs deliver the teletext rgb signal to the additional rgb inputs (pins 30 to 32) of the vcu 2133 or vcu 2134 in the case of teletext operation. the fast blanking output serves for switching the video chan- nel between normal tv and teletext operation. it must be connected to the fast blanking input (pin 33) of the vcu. pin 10 fast blanking input (fig. 310) this pin is used to switch over to an external rgb source. the external rgb signal is connected to pins 32 to 34 of the tpu 2735. a low level at pin 10 switches the external rgb signal to the rgb outputs of the tpu 2735 and enables the fast blanking output (pin 9 high). pin 10 floats to a high level if not connected. the rgbe control bit sets the priority to the external rgb inputs if both, teletext and external rgb are active. two bits in the im bus hardware test/configuration register (see section 6.4.) allow to select the polarity of pin 10 and overwrite the fast blank signal.boxes of tpu text can be cut into an external rgb signal. the rgb and blanking outputs are controlled according to the table below. the settings ttm=1 and rgbe=0 are recommended for normal teletext. for on-screen display, ttm=1 and rgbe=1 are recommended. for clarification, the con- nections are shown in fig. 32 and the tv display ap- pearance in fig. 33. tpu 2735 vcu video from vcu teletext rgb bl logic rgbe flag ext. rgb 32, 33, 34 14, 15, 16 im bus 33 30, 31, 32 9 6, 7, 8 26, 27, 28 rgb to crt chroma and luma from vpu or cvpu 10 fig. 33: signal paths for rgb signals in tpu 2735 and vcu 2133 or vcu 2134 on-scr . display tv scart (ext. rgb) on- screen display (text) insert mode = fbl (pin 10) active low a) ttm = 1, rgbe= 0 b) ttm = 1, rgbe = 1 tv fig. 34: priorities on the screen, depending on ttm and rgbe scart ext.rgb ttm rgbe ext. fast blanking pin 10 internal tpu text blank- ing fast blank- ing output pin 9 rgb output pins 6 to 8 screen* 0 0 0 1 1 1 1 1 1 0 1 0 0 0 0 1 1 1 1 x 0 1 1 0 x 1 0 0 0 0 0 1 x 1 0 0 0 1 1 0 1 1 1 0 1 pins 32 to 34 pins 32 to 34 pins 32 to 34 text text pins 32 to 34 text pins 32 to 34 pins 32 to 34 video scart scart video text scart text video scart x = don't care * = see fig. 32 and 33
tpu 2735 9 pin 11 undelayed horizontal blanking pulse/ d2sync input (fig. 38) this pin is connected to the undelayed horizontal blank- ing output of the deflection processor dpu25xx. for d2mac teletext mode this pin is also connected to the d2sync output of the d2mac processor dma2270. (both pins are tristate outputs). pin 12 vertical blanking pulse (fig. 38) this pin is connected to the acombined delayed horizon- tal and vertical blanking pulseo output of the dpu25xx. pin 13 reset input (fig. 38) provided a clock is present at pin 36, a low level at pin 9 resets the internal circuitry of the tpu 2735. for nor- mal operation high level is required. pins 14 to 16 im bus connections by means of these pins, the tpu 2735 is linked with the ccu. pins 15 (ident input) and 16 (clock input) are con- figured as shown in fig. 38. pin 14 (data input/output) is shown in fig. 39. the data transfer via the im bus is explained in section 6. pin 17 to 19, 21 to 26 dram address outputs (fig. 37) pin 27 dram data input/output (fig. 310) pin 28 read/write output (fig. 37) this output supplies the r/w control signal to the exter- nal dram. pin 29 cas output (fig. 37) this output supplies the column address select (cas) signal for the external dram. pin 30 ras output (fig. 37) this output supplies the row address select (ras) sig- nal for the external dram. pin 31 deflection skew data input (fig. 311) this pin can be connected to pin 7 of the dpu 25xx de- flection processor. when dsen = 1 (see r-dac of reg- ister chain 2) this input controls the horizontal position of the teletext rgb signal. pins 32 to 34 rgb inputs (fig. 36) these pins can be connected to an external rgb source. the specified level of these signals is 0 v to 0.7 v. for other dc levels, an ac coupling has to be used to pins 32 to 34, and a clamping circuit in the vcu has to adjust the dc level. pin 35 v sup , 5v supply voltage pin 36 f m main clock input (fig. 312) via this pin the tpu 2735 is supplied with the required main clock signal of 20.25, 17.7, 14.4 mhz produced by the mcu 2600 or mcu 2632 clock generator ic. pin 38 d2data input (fig. 38) for d2mac teletext acquisition this pin is connected to the d2data output of the dma 2270.
tpu 2735 10 3.4. pin circuits (pin numbers for 40-pin dil package) the following figures schematically show the circuitry at the various pins. the integrated protection structures are not shown. the letter aeo means enhancement, the letter ado depletion. +5 v +0.7 v 6,7,8 0 34, e e e v sup gnd e e v sup gnd e d dd ee v sup bias gnd 33, 32 fig. 35: pins 1 to 4, 39, 40, inputs fig. 36: pins 6 to 8 and 32 to 34, rgb inputs and outputs fig. 37: pins 9, 17, 18, 19, 21 to 26, 28, 29, 30, outputs fig. 38: pins 11 to 13, 15, 16 and 38, in- puts d e bias gnd v sup d e d d v sup gnd bias v sup gnd d e e e d e e v sup gnd fig. 39: pin 14, input/output fig. 310: pin 27, input/output fig. 311: pin 10, 31, inputs fig. 312: pin 36, input
tpu 2735 11 3.5. electrical characteristics all voltages refer to pin 5, all pin numbers refer to dil package. 3.5.1. absolute maximum ratings symbol parameter pin no. min. max. unit t a ambient operating temper- ature 0 65 c t s storage temperature 40 +125 c v sup supply voltage 35 6 v v i input voltage, all inputs 0.3v v sup v o output voltage, all outputs 0.3v v sup i o output voltage, all outputs the push-pull outputs are short-cir- cuit-proof with respect to ground and supply. 3.5.2. recommended operating conditions at t a = 0 c to 65 c, f c = 14.3 to 20.3 mhz symbol parameter pin no. min. typ. max. unit test conditions v sup supply voltage 35 4.75 5.0 5.25 v v ih input voltage high, video inputs 39, 40, 1 to 4 v sup /2 +0.3 v v il input voltage low, video inputs v sup /2 0.3 v v ih input voltage high, fast blank input 10 0.9 v v il input voltage low, fast blank input 10 0.5 v v ih input voltage high 11, 12, 14, 15, 16 2.4 v v il input voltage low 11, 12, 14, 15, 16 0.8 v v ih input voltage high, reset input 13 2.4 v v il input voltage low, reset input 13 1.2 v v ih input current high, skew data input 31 20 m a v il input voltage low, skew data input 31 1.2 v
tpu 2735 12 recommended operating conditions, continued symbol parameter pin no. min. typ. max. unit test conditions v i input voltage, analog rgb in- puts 32, 33, 34 0.7 1 v pp v pp input voltage swing, clock in- put 36 0.8 2.4 v pp v dc input voltage dc level, clock input 36 1.5 3.5 v v ih input voltage high, d2data input 38 2.4 v v il input voltage low, d2data input 38 0.8 v f c clock frequency, pal 36 17.7 mhz f c clock frequency, ntsc 36 14.4 mhz f c clock frequency, d2mac 36 20.25 mhz c l load capacitance, dram inter- face 17, 18, 19 21 to 30 30 pf t s input setup time, video inputs, pal/ntsc 39, 40, 1 to 4 9 ns ref. to neg. clock edge t h input hold time, video inputs pal/ntsc 8 ns ref. to neg. clock edge t s input setup time, h input pal/ntsc 11 0 ns ref. to neg. clock edge t h input hold time, h input pal/ ntsc 11 20 ns ref. to neg. clock edge t s input setup time, h input d2mac 11 10 ns ref. to pos. clock edge t h input hold time, h input d2mac 11 25 ns ref. to pos. clock edge t v pulse width, v input 12 58 h (64 m s) t s input setup time, d2data input 38 5 ns ref. to pos. clock edge t h input hold time, d2data input 38 10 ns ref. to pos. clock edge
tpu 2735 13 t s t h clock data inputs data inputs timing chart and symbols (ref to neg. clock edge) 3.5.3. characteristics of the digital section , t a = 0 c to 65 c symbol parameter pin no. min. typ. max. unit test conditions i sup supply current 35 200 240 at 0 c v oh output voltage, high fast blank output 9 3.5 v i o = 0.1 ma v ol output voltage, low fast blank output 9 0.6 v i o = 1.6 ma v ol output voltage, low im bus data 14 0.4 v i o = 3.0 ma v oh output voltage, high dram in- terface 17, 18, 19, 21 to 30 3.5 v i o = 0.1 ma v ol output voltage, low dram in- terface 17, 18, 19, 21 to 30 0.6 v i o = 1.6 ma c i input capacitance 39, 40, 1 to 4, 11, 12, 13, 14, 15, 16, 31, 36 5 pf 3.5.4. characteristics, rgb interface rgb inputs terminated with 75 w, rgb outputs terminated with 1 m w 20 pf symbol parameter pin no. min. typ. max. unit test conditions internal rgb outputs v ol rgb output voltage low 6, 7, 8 20 50 mv v oh rgb output voltage high 6, 7, 8 0.14 v sup v oh rgb output voltage high 6, 7, 8 630 700 770 mv v sup = 5v
tpu 2735 14 characteristics, continued symbol parameter pin no. min. typ. max. unit test conditions d v oh differential rgb output volt- age, high 6, 7, 8 20 50 mv v sup = 5v d v ol differential rgb output volt- age, low 6, 7, 8 10 mv v sup = 5v v n noise at rgb outputs 6, 7, 8 10 mv rms teletext mode, b w = 6 mhz external rgb interface c i input capacitance rgb inputs 34, 33, 32 10 pf r on resistance from rgb inputs to rgb outputs 6, 7, 8 to 34, 33, 32 200 300 w ext. inputs on d r on differential resistance 6, 7, 8 to 34, 33, 32 10 w ext. inputs on r off resistance from rgb inputs to rgb outputs 6, 7, 8 to 34, 33, 32 1 m w ext. inputs off b w bandwidth ext. rgb 6, 7, 8 to 34, 33, 32 6 mhz ext. inputs on a cross-talk rgb inputs to rgb intern 6, 7, 8 to 34, 33, 32 50 db measured at rgb outputs, ext. inputs off b w = 6 mhz a cross-talk rgb inputs to rgb inputs 6, 7, 8 to 34, 33, 32 35 db measured at rgb outputs, ext. inputs on b w = 6 mhz v n noise at rgb outputs 6, 7, 8 5 mv rms ext. inputs on b w = 6 mhz 3.5.5. characteristics of the external ram the tpu 2735 is designed to control one dynamic 64 kbit or 256 kbit ram. the essential ram characteris- tics are: page mode capability access time from cas 100ns 256 cycle 4 ms refresh (a0 to a7) max. ras pulsewidth 10 m s data in setup time 0ns address setup time 0ns fig. 313: ras and cas timing ras cas t cas h t cas l pal ntsc d2mac t cas h 85 ns 104 ns 85 ns t cas l 113 ns 104 ns 113 ns
tpu 2735 15 4. various operation modes of the tpu 2735 4.1. the menu mode in the menu mode, on the screen of the tv set is dis- played a list of contents of the ram. this list is achieved by displaying row 0 of all sectors at the same time (fig. 41). each row 0 is supplemented by the sector number and the requested page number. these two informa- tions are placed at the beginning of each row 0 in the same way as the status indicator. the menu is displayed immediately if men (r-dc1) is set to 1. the lower part of the menu cannot be displayed in double-height mode. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 > 3 1 5 1 3 1 1 2 3 1 2 3 3 1 4 4 3 1 5 5 4 1 0 6 1 2 0 7 2 1 0 8 1 5 0 (page header of selected sector) row 0 of sector 0 row 0 of sector 1 row 0 of sector 2 row 0 of sector 3 row 0 of sector 4 row 0 of sector 5 row 0 of sector 6 row 0 of sector 7 status indicator fig. 41: display of the menu on the screen (example) 4.2. teletext display without interlaced lines in this operation mode, the flicker of the tv screen is re- duced. for this, the tpu 2735 can distinguish between field 1 and field 2 of a tv frame. if the tpu 2735 is sup- plied by sync signals without interlace, the character rounding of normal height characters is switched off automatically thus enabling a balanced display of a teletext page displayed without interlaced lines. the dpu 25.. deflection processor unit can provide appro- priate sync signals on request of the ccu. when a subtitle or a newsflash page is displayed with both tv picture and teletext characters on the screen, the tpu 2735 sets a flag (tvs = 1 in r-dc3) to indicate that a display with interlaced lines is referable. 4.3. the effect of errors in the transmission of teletext data 4.3.1. errors in the hamming-code protected data single errors are corrected and have no further effect. rows with multiple errors are not loaded into the dram. the error flag of this page number is set and the tpu tries to read this page when it occurs again without clear- ing the previously acquired data. 4.3.2. errors in data with parity check data with parity errors is not written to the ram. a parity error sets the error flag of the received page number. the tpu tries to read this page again without clearing the previously acquired data. 4.4. multipage conflict situation a conflict situation arises if the tpu 2735 receives a new page while the reception of another requested page has not been finished. this situation comes up if requested pages of different magazine numbers are transmitted with interleaved rows or if the last page of a block of pages from the same magazine is requested. in a conflict situation only the first page is stored immedi- ately. the others have to wait until they are transmitted again. a page which has a conflict with another page loses its priority over the following page when it is stored and regains priority when all pages involved in a conflict have been stored. the selected page does not loose its priority to guarantee the updating of the display.
tpu 2735 16 5. ram organization the external ram is a 64 kbit or 256 kbit dynamic ram. a ram sector is defined as 8 kbit and is capable to store the information of one teletext page. a 64 kbit ram holds 8 sectors, a 256 kbit ram is organ- ized as 4 blocks of 8 sectors. a ram sector is organized in 25 rows of 40 bytes (row 0 to row 24) and one row of 24 bytes (row 25). the first 8 bytes of row 0 and the first 11 bytes of row 25 of each sector contain control and status information for the stored teletext page. row 24 of sector 0 in block 0 is used as a register for con- trol information from the control microprocessor. when the TPU2735 is used in flof mode sector 0 of each block is used to store row 27 teletext information. in the extended character set (ecs) mode the TPU2735 stores row 26 information in the sector preceding the current acquisition sector. ram organization is summa- rized in the following table: table 51: memory organization of sector n block m row number row 0 row 1 . . row 14 row 15 row 16 row 17 row 18 . . row 23 row 24 row 24 row 26 des.code 0 of sector n+1 in ecs mode, n even only row 26 des.code 1 of sector n+1 o . . row 26 des.code 14 of sector n+1 o row 8/30* in sector 0, block 0 only rolling header flof, ecs mode, sector 0, block 0 only row 27* of ttx page in sector 1 in sector 0, block 0 ... 3 row 27* of ttx page in sector 2 o . . row 27* of ttx page in sector 7 o register chain 2 in sector 0, block 0 only rolling header in sector 1, block 0 if flof, ecs are not selected *) only designation code 000x is stored row 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 column 24 25 0123456 7 8 9101112131415161718192021222324 25 2627282930313233343536373839 control bits time register chain 2 register chain 1 teletext data fig. 51: organization for 64 kbit ram, divided into 8 sectors, sector 0 shown
tpu 2735 17 6. controlling the tpu 2735 with the ccu 2030, ccu 2050 or ccu 2070 tpu and ccu communicate via the im bus. the ccu can read from and write to all ram locations of the tpu system and can test the status (ready/busy) of the con- trol interface of the tpu. the ccu can control the tpu by addressing the control registers in the ram. the tpu 2735 distinguishes the following types of com- mands: command im bus address read a 16-bit write address read a 16-bit read address 8-bit data transfer (read or write) status test hardware test/configuration 7 a (hex) 7 b (hex) 7 c (hex) 7 d (hex) 7 e (hex) each type of command has its own im bus address. the tpu has accomplished a ccu command when the busy flags are 0. every data transfer starts with a tpu status check, i.e. a read status command with status equal to zero. next the read or write address is transferred. after the ad- dress command another status check is required. the subsequent data is written to or read from the ram ac- cording to the preceding address command. the ram address is incremented after each data transfer. address check status data read next address (auto increment) check status fig. 61: command sequence for reading data from tpu to ccu with optional auto increment address check status data write next address (auto increment) check status fig. 62: command sequence for writing data from tpu to ccu with optional auto increment the maximum busy time is 2.5 ms. the test of the inter- face status can be followed immediately by another command if the busy flag was low or by a second test if the busy flag was high. 6.1. the address commands the 16-bit address consists of four parts: block address (0 to 3) 2 bits sector address (0 to 7) 3 bits row address (0 to 25) 5 bits column address (0 to 39) 6 bits each sector defines the memory locations for a teletext page and consists of 25 rows. the rows 0 to 24 can be used as display memory, row 24 and row 25 can be used as control registers. the row and column addresses cor- respond to the position of the character display on the screen. the data format of the address (c 0 being trans- mitted first) is: c 5 ... c 0 ... block address msb sector address row address column address lsb b 1 b 0 s 2 s 1 s 0 r 4 r 0
tpu 2735 18 6.2. the data transfer command a data command transfers 8 bits of data from the ccu to the tpu or vice versa. the transfer direction depends on the type of the last address command before the data transfer command. a data transfer command following a read address command makes the tpu answer with 8 bits of data. the lsb is transmitted first. d7 d6 d5 d4 d3 d2 d1 d0 msb lsb the ram address of subsequent data transfer com- mands is automatically incremented by 1. however, the sector address is not incremented on row address over- flow. read address command write address command data transfer command ram address busy 1 busy 2 n 1 n 1 +1 n 1 +2 n 1 +3 n 2 n 2 +1 fig. 63: example of a read/write command sequence 6.3. the status test command the tpu answers to this command with an 8-bit status word: 0 0 0 0 0 0 bui 2 bui 1 msb lsb the busy flags indicate the status of the interface as fol- lows: bui 1 bui 2 interface status 0 1 1 0 0 1 ready for commands not ready for commands ready only for address commands 6.4. the im bus hardware test/configuration register this register allows to control the polarity and the state of the fast blank input signal. the register is write only and is cleared with hardware reset. all unused bits must be set to zero. 0000 d7 d6 d5 d4 d3 d2 d1 d0 fbp fbo 0 0 fbp: fast blank polarity: 0 active low (compatible with tpu 2732) 1 active high fbo: fast blank overwrite: 0 no action 1 set fast blank to 1 (internally) in this state fbp allows to switch the fb signal under program control.
tpu 2735 19 7. the control registers of register chain 2 the registers which are used by the ccu to control the tpu have the addresses 0/24/0 to 0/24/30 and are des- ignated as register chain 2. the following pages define the function of the individual registers. an asterisk* marks those bits which can be modified by the tpu. in a write access, each undefined control bit must be set to zero to ensure future compatibility. register chain 2 address bytes name 0/24/0 2 2 2 2 2 2 2 2 2 2 1 1 2 1 1 1 2 4 6 8 10 12 14 0/24/16 18 20 21 22 0/24/24 25 26 27 0/24/30 rpr0 rpr1 rpr2 rpr3 rpr4 rpr5 rpr6 rpr7 rps rsc rds rdac rsi rdc1 rdc3 rdc4 rdc5 rdc6 rmc page request page selection subcode display selection data acquistion control status indicator memory control 28 29 1 1 1 rdc2 display control 1 7.1. the page request registers, r-prx each sector of the acquisition block has its own page re- quest register. their structure can be seen below. they have to be loaded with the page numbers of the pages which shall be stored in the according sector when the tpu receives this page. if more than one register con- tains the same page number the register with the lowest sector number has the highest priority. r-prx page request registers address 0/24/2x, 2-byte register msb lsb msb lsb d7 d6 d5 d4 d3 d2 d1 d0 tens bcd units bcd requested page number res nrfx erfx lsb d7 d6 d5 d4 d3 d2 d1 d0 requested magazine nufx cf1x msb number (binary, 0 0 0 ** * 8) x is the sector number where the page is to be stored. res: bit is reserved, set to zero nufx: no updating flag nufx = 1 prevents the data acquisition unit of the tpu from writing to the ram sector x. nufx can be used in the halt mode to protect a received page against modi- fications. erfx: error flag the tpu sets erfx = 1 if a bit error was detected during the reception of a teletext page. the tpu will load a page with erfx = 1 once again as soon as it is transmit- ted again. erfx has to be reset when the page request register is loaded with a new page number. nrfx: new request flag nrfx has to be set to 1 if the ccu loads a new request into r-prx. the tpu resets nrfx when the requested page has been received. nrfx influences the page header (rolling header and color) when sector x or the menu is displayed (see section 7.5. adata acquisition register r-dac 1o). cf1x: conflict flag 1 cf1x: = 1 indicates a conflict situation where the re- quested page of sector x is involved. cf1x = 1 leads to a longer access time (see section 4.4. amultipage con- flict situationo). cf1x has to be reset when the page re- quest register is loaded with a new page number.
tpu 2735 20 7.2. the page selection register, r-ps the ccu can write a number of a page into r-ps when this page has been requested before and shall now be displayed. r-ps has only effect if sic = 1. (see section 9., atwo ways to select a page for displayo). r-ps page selection register address 0/24/16, 2-byte register d7 d6 d5 d4 d3 d2 d1 d0 tens bcd units bcd page number selected for display txid flof oe d7 d6 d5 d4 d3 d2 d1 d0 magazine number opn dpc * (binary, 0 0 0 8) txid: teletext transmission indicator txid = 1 if a teletext line was detected in the vertical flyback interval. opn: open opn = 1 makes the tpu receive a requested page whenever it is transmitted. opn = 0 makes the tpu re- ceive a requested page only if nrf = 1, or errors have been detected (erf = 1), or c 4 = 1 or c 8 = 1 (clear page or update page). dpc: disable parity checking dpc = 1 disables parity checking for the data bytes of all received ttx rows. flof: enable flof mode flof = 1 enables reception of rows 24, 27 and 8/30. oe: odd/even data sampling oe = 0 samples the odd data bits off the d2data signal, oe=1 samples the even data bits. this bit is used to se- lect the ttx data channel for dmac vbi ttx data. 7.3. the subcode register, r-sc the subcode register can be used to make the tpu 2735 respond only to transmitted pages with the sub- code specified in r-sc. the subcode is normally inter- preted as a time code. r-sc subcode register address 0/24/18, 2-byte register ssc0 scu3 scu0 d7 d6 d5 d4 d3 d2 d1 d0 sct2 sct1 sct0 scu2 scu1 sct: subcode tens (minutes tens) scu: subcode units (minutes units) ssc2 sch3 sch0 d7 d6 d5 d4 d3 d2 d1 d0 ssc1 scm1 scm0 sch2 sch1 sc: subcode control scm: subcode thousands (hours tens) sch: subcode hundreds (hours units) the subcode-control flags scc 0 to scc 2 determine for which sector the subcode is valid. subcode control flags subcode valid only for sector 1 ssc2 ssc1 ssc0 function 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 subcode ignored subcode valid only for sector 2 subcode valid only for sector 3 subcode valid only for sector 4 subcode valid only for sector 5 subcode valid only for sector 6 subcode valid for all sectors
tpu 2735 21 7.4. the display selection register, r-ds r-ds controls the selection of a ram sector for display. the sector number of the displayed sector is either de- termined by the tpu using r-ps or by the ccu. r-ds display selection register address 0/24/20, 1-byte register ers rps rpsv lsb d7 d6 d5 d4 d3 d2 d1 d0 sector number of sic nrs msb ***** * displayed sector ers: error flag of the selected page ers = 1 means: the selected page has been received with errors. ers is for internal use of the tpu 2735. sic: start internal comparison the ccu has to set sic = 1 when a new page number is loaded into r-ps. sic is reset by the tpu when rps is valid. nrs: new request flag of the selected page nrs = 1 means: the selected page has not yet been re- ceived. nrs is only for internal use of the tpu. rps: requested page is selected the tpu sets rps to 1 if a page number of one of the eight request registers is identical to the selected page number of r-ps (see section 9., atwo ways to select a page for displayo). when rps is set to one and display (r-dc3) and acquisition block (r-mc) are different, the current magazine (in parallel magazine mode) is taken from r-ps. rpsv: rps flag valid only if rpsv = 1 the value of rps is valid. when r-ps has been loaded with a new page number the tpu ac- complishes a comparison within 20 ms. the result is written into r-ds. when a comparison is accomplished rpsv is set to 1. the ccu can reset rpsv after loading r-ps and then check if rpsv is set to 1 again. 7.5. the data acquisition control register, r-dac this register controls the slicer, the ghost compensation, the acquisition of the page header and the skew data. r-dac data acquisition control register address 0/24/21, 1-byte register tbd nrh rgc d7 d6 d5 d4 d3 d2 d1 d0 dsen rha nrt nda ngc * tbd: vertical blanking delay set to 1 if the delay between horizontal and vertical blanking pulse is more than 32 ms in field 1 of a tv frame. tbd is used to adapt the tpu 2735 to different sources of the blanking pulses required for synchroniza- tion of the tpu (see fig. 71). tbd must be set to 0 in d2mac mode. dsen: deflection skew data enable dsen = 0: the horizontal display start is controlled by pin 11. dsen = 1: the horizontal display start is controlled by pin 31 (skew data). the tpu 2735 is able to adjust the horizontal phase of the teletext rgb signal under control of deflection skew data (dsd) at pin 31. the phase can be adjusted by steps of 1/16 of the main clock period, i. e. 3.5 ns for pal and 4.4 ns for ntsc. dsd provides a teletext picture without visible jitter even when there is no color burst in the video signal and the dpu is not in the locked mode. for more details refer to the description of the dpu 25.. deflection processor. rha: nrt: nrh: rolling header always no rolling time no rolling header refer to table rolling header options nda: no data acquisition; default value is nda = 0. if nda = 1, the teletext data acquisition is switched off. ngc: no ghost compensation ngc = 1 switches off the ghost compensation rgc : reset ghost compensation; zero written to this bit resets the ghost compensation fil- ter; returns automatically to 1 when the reset command is executed.
tpu 2735 22 rha nrt nrh option 0 0 0 0 1 0 0 1 1 0 0 1 0 1 0 rolling header while searching only time is rolling only central header section header does not change rolling header always the selected page, rolling time always is rolling while searching (recommended for ntsc mode) rolling header options 1 x 1 ignore parallel magazine control bit (c11 in 8.4.) for rolling header acquisition t d < t d > tbd = 0 tbd =1 composite sync signal horizontal fig. 71: timing diagram for the horizontal and verti- cal blanking pulses t az and t ab for two cases 32 m s 32 m s pulse t az blanking vertical blanking pulse t ab in line no. 1 7.6. the status indicator register, r-si the contents of r-si determine the eight characters of the status indicator in left corner of row 0. the status indi- cator displays three numerals which represent a page number. pmi and nvmi determine the mode of their dis- play: page symbol list pmi nvmi display mode 0 1 0 1 0 0 1 1 white, steady light-blue, steady yellow, steady red, flashing r-si status indicator register address 0/24/22, 2-byte register msb lsb msb lsb d7 d6 d5 d4 d3 d2 d1 d0 tens bcd units bcd indicated page number pmi nvmi d7 d6 d5 d4 d3 d2 d1 d0 indicated magazine number page symbol (binary, 0 0 0 8) pmi: programming mode indicator; pmi = 1 changes the color of the indicated page number to blue. pmi can be used to indicate that a new page number is not complete or has not yet been accepted. nvmi: non-volatile memory indicator; nvmi = 1 changes the color of the indicator to yellow page symbol list d6 d5 d4 page symbols 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 aspaceo r s t = > ? p page header >100 fig. 72: display of the status indicator in the left corner of row 0
tpu 2735 23 7.7. the display control registers, r-dc1 to r-dc6 the flags of r-dc1 determine the way the control infor- mation (page header, status indicator, time, menu) is displayed. the flags of r-dc2 and r-dc4 determine the way the teletext page is displayed. the flags of r-dc5 determine which character set is used. r-dc1 display control register 1 address 0/24/24, 1-byte register toe bxt pah hlt d7 d6 d5 d4 d3 d2 d1 d0 men tof ind *** ** tim toe: timeout enable toe = 1 enables the automatic reset of bxt, pah, ind and tim after 5 s for pal or 4 s for ntsc. men: display menu men = 0 means normal display, and men = 1 means that the menu is displayed. tof: text off tv picture is displayed (bl = 0) bxt: display boxes (with time-out option) in a tv picture pah: display page header if pah is set to 1 by the ccu, a 5 second timer is started. during these 5 sec the row 0 of the selected sector is dis- played. thereafter, pah is reset to 0. time-out can be switched off by toe = 0. if pah, tof and ttm are 1, the row 0 of the selected sector is boxed in the normal tv picture. ind: display indicator (with time-out option) similar to pah, but the first eight characters of row 0 of the selected sector are displayed. tim: display time (with time-out option) similar to pah, but the last eight characters of row 0 of the selected sector are displayed in white. hlt: indicate halt mode if hlt = 1 the last eight characters of the displayed page header are replaced by a symbol which indicates that the page is not updated. tim has priority over hlt. pah and bxt are influenced by the data acquisition con- trol according to the following table: requested page sector n is subtitle page clear page update page nrfx set pah 0 1 1 1 1 1 x 0 1 1 1 1 x x x 0 0 1 x x x 1 x x x x x x 1 x x x 1 x x 0 0 0 1 0 1 1 x = don't care display behaviour of updated pages and bxt selected for display of sector n is received
tpu 2735 24 r-dc2 display control register 2 address 0/24/25, 1-byte register ttm mix upi dht d7 d6 d5 d4 d3 d2 d1 d0 dw dr rev * dlb ttm: teletext mode if ttm = 0, no teletext data is displayed. the r, g, b in- puts are connected to the r, g, b outputs. the state of the fast blanking output depends on the fast blanking input and the rgbe control bit (ref. section 7.8.). if ttm = 1, teletext data is displayed according to the status of the control registers. dw,dr: double width dw = 0 and dht = 0 means normal display. dw = 1 and dr = 0 displays the left half of the teletext page in double width characters. if dr = 1 and dw = 1, the right half of the screen is shown in double width; any attribute char- acters that are in the left half of the page will have no ef- fect. dw = 1 and dht = 1 means double size display. in this case dr and dlb select 1 of 4 possible display quadrants. mix: mixed display if mix = 1, characters may be displayed with tv back- ground. the margin background is tv picture (see table below). upi: update indicator default value is upi = 0. upi is set by the tpu whenever the page which is selected for display is updated. upi is not reset by the tpu. the ccu may monitor upi and re- set upi after an update has been detected. rev: reveal if rev = 1, the conceal control character 1/8 has no ef- fect. dlb: display large bottom dlb has no effect if dht = 0, see dht. dht: double height dht = 0 and dw = 0 means normal display. dht = 1 and dlb = 0 means large top. dht = 1 and dlb = 1 means large bottom. in connection with control character 0/13 some characters may not be fourfold high 0/13 has no effect. r-dc3 display control register 3 address 0/24/26, 1-byte register tvs x x x d7 d6 d5 d4 d3 d2 d1 d0 db1 db0 x * x tvs: tv synchronization required (mixed mode) the tpu sets tvs = 1 if the displayed teletext page con- sists of mixed data tv/teletext, e. g. mix = 1, c6 = 1 (subtitle), c5 = 1 (newsflash). db: display block address (0 to 3) of the current block (8 pages) to display. x: for internal use only should not be modified via im bus. mix bxt tof pah ind tim normal box indicator header time background 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 0 1 0 0 0 1 0 1 1 1 1 1 1 1 1 x x 0 1 0 x 1 0 0 0 0 1 1 1 1 0 1 1 x 0 0 1 1 1 1 1 1 1 1 x 0 0 0 0 0 0 0 1 0 0 0 1 0 0 x 0 0 0 0 0 0 0 0 1 0 0 0 1 0 x 0 0 0 0 0 0 0 0 0 1 0 0 0 1 tt tv tv tv tv tv tv tv tv tv tv tv tt tt tt tv tt tv tv tt tt tt tt tt tt tt tt tv tv tv tv tt tt tv tv tt tt tv tt tv tv tv tv tt tv tv tv tt tv tv tt tv tv tv tv tt tv tt tv tt tv tt tt = teletext = not displayed c 5 or c 6
tpu 2735 25 r-dc4 display control register 4 address 0/24/27, 1-byte register ino mac nts ncr d7 d6 d5 d4 d3 d2 d1 d0 ibl ntsc nhs d2 nfl ino: inverted outputs (r, g, b and fast blank- ing) ibl: inverse blanking if ibl = 1, the fast blanking output is inverted. ntsc: ntsc mode d2mac: d2mac mode nts: no text suppression nts = 1 disables control bit c10. nhs: no header suppression nhs = 1 disables control bit c7. nfl: no flash nfl = 1 disables control character 0/8. ncr: no character rounding ncr = 0 means character rounding on, and ncr = 1 is character rounding off. if the tpu 2735 is supplied by a sync signal with non-interlaced lines, character rounding is turned off automatically for normal height characters. double height characters are displayed with character rounding unless ncr = 1. r-dc5 display control register 5 address 0/24/28, 1-byte register iisp upen els ls 0 d7 d6 d5 d4 d3 d2 d1 d0 uks ecs ls 2 ls 1 iisp: indicator insertion suppression iisp = 1 suppresses the display of the status indicator and displays the memory locations x/0/0 to x/0/7 in- stead. uks: swap uk/us english character set default value is uks = 0, (ref. to table below). uks = 0: the uk character set is displayed in pal mode. the us character set is displayed in ntsc mode. uks =1: the us character set is displayed in pal mode. the uk character set is displayed in ntsc mode. ecs: extended character set mode reception of rows x/26 and additional (spanish) charac- ter set are enabled. the memory organization is changed in order to store the row x/26 for each sector (please ref. to sect. 5 pg. 16). two additional control characters `0x0: alpha black' and `0x10: mosaic black' are processed. additional characters for the spanish teletext system are provided, these characters overlay the control characters with bit 7 (msb) set. upen: update enable default value is upen = 0. upen = 1prevents btx and pah from being set when the displayed page is updated. only the update indicator upi will be set and the software may decide about the way an update is shown on the display. els: external language selection els = 1: the selection of the different character sets is under software control, using the display control register r-dc5 (ls2, ls1 and ls0). els = 0: the selection of the different character sets is under transmitter control, using the control bits c12, c13 and c14 of the page header. lsx: language select code english, us version character set selected 0 0 0 0 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 0 1 0 1 0 english, uk version english, us version english, uk version german scandinavian italian french/belgian spanish english, us version reserved ls2 ls1 ls0 ntsc mode uks 1 1 1 0 1 1 1 0 1 0 1 0 1 x x x x x x x 0 0 1 1 x x x x x x x x = don't care c 12 c 13 c 14
tpu 2735 26 r-dc6 display control register 6 address 0/24/29, 1-byte register ds hda hda hda d7 d6 d5 d4 d3 d2 d1 d0 dls hda hda hda ds: double-scan mode ds = 1 doubles the display frequencies. when ds = 1 and dsen = 0, the rgb horizontal period is 567.5 main clock periods for pal and 515 main clock periods for ntsc. dls: display lines dls = 0 selects 24 display lines. dls = 1 selects 25 dis- play lines. dls = 1 is only valid in pal, d2mac modes. row flag rro is used to control line 25, (see section 8.5.). dls also effects the number of lines cleared with the cds (clear display sector) command (see section 7.8.). hda: horizontal display adjustment a 6-bit binary number can be loaded into hda to shift the teletext picture from the left towards the right edge of the screen. the additional rgb delay generated by hda is in steps of 1/4 character. = 12.2 m s for pal/d2mac and 10.8 page width pin 11 hor. blanking pin 31 defl. skew data rgb out = minimum delay of the horizontal rgb start from dsd at pin 31 (dsen = 1) = minimum delay of the horizontal rgb start from horizontal blanking at pin 11 (dsen = 0) = 15.6 m s for pal/d2mac and 14.6 m s for ntsc m s for ntsc fig. 73: horizontal display start in normal scan mode t d1 t d0 t d0 t d1 t d1 t d0 t hda t d1 t d0 page width pin 11 hor. blanking pin 31 defl. skew data pins 6 to 8 rgb out = minimum delay of the horizontal rgb start from dsd at pin 31 (dsen = 1) = minimum delay of the horizontal rgb start from horizontal blanking at pin 11 (dsen = 0) = 10.4 m s for pal and 10.8 m s for ntsc = 6.9 m s for pal and 6.4 m s for ntsc fig. 74: horizontal display start in double-scan mode t d1 t d0 t d1 t d0 t d1 t hda t hda main clock double scan double width pixel width ( page width 56.4/49.4 ns in ntsc mode the teletext page is about 18% smaller than in pal mode. display timing period t 69.8 ns 69.8 ns 69.8 ns 69.8 ns pal/d2mac pal/d2mac pal/d2mac pal/d2mac ntsc ntsc ntsc ntsc 0 1 0 1 0 1 0 1 0 0 1 1 0 0 1 1 169.2 ns = 3 84.6 ns = 1.5 338.3 ns = 6 169.2 ns = 3 139.7 ns = 2 69.8 ns = 1 279.4 ns = 4 139.7 ns = 2 40.6 20.3 33.5 16.7 m s) 56.4/49.4 ns 56.4/49.4 ns 56.4/49.4 ns ? t ? t ? t ? t ? t ? t ? t ? t
tpu 2735 27 7.8. the memory control register, r-mc r-mc provides an easy way to clear parts of the se- lected ram sector. r-mc memory control register address 0/24/30, 1-byte register rgbe abo sst cr2 d7 d6 d5 d4 d3 d2 d1 d0 rgbi ab1 cds *** cr1 * rgbe: switch external rgb signal to the rgb outputs (see section 3.3., pin 10). rgbi: indicator for external blanking in line 6, i.e. constant external blanking abx: address of current acquisition block sst: is for testing purposes only sst = stop on same page header. sst = 1 makes the tpu close a page whenever a new page header of the same magazine is received. default value is sst = 0. cds: clear display sector; cds = 1 clears the data part of the selected display sec- tor. depending on the dls control bit in r_dc5 of rc2, 24 or 25 lines of the sector will be written. also the adisplay header optionso (ref. to r_dac in section 7.5) influence the write operation: if arolling headero or arolling timeo is selected, the respective areas in the rolling header and/or rolling time fields are cleared and the contents of the current display page remains unchanged. if cds is set to 1 the display period of the subsequent field is turned into an erase period: read is turned to write, and data is stuck to blank (0x20). the next field resets cds to 0. cr1: clear register chain 1 of the selected display sector cr2: clear register chain 2 cr1(2) = 1 clears all bits of all registers of register chain 1(2). this is done in the field following the clear com- mand in line 25, 26. cr1(2) is reset by the tpu when the clear command is executed. power-up reset makes cr2 = 1.
tpu 2735 28 8. the control registers of register chain 1 each ram sector has its own registers for internal con- trol purposes. these registers are designated as regis- ter chain 1 (of sector x) and have the addresses x/25/0 to x/25/10. they are used for control information of the teletext transmitter and information about the status of the data acquisition. in a normal teletext mode the ccu does not read or modify these registers. the following pages define the function of the individual registers. in a write access, each undefined control bit must be set to zero to ensure future compatibility. register chain 1 of sector x address bytes name x/25/0 2 6 1 1 1 x/25/5 x/25/2 3 4 rpi rrf rcb1 rcb3 page identification row flags rcb2 control bits 8.1. the page identification register, r-pi address x/25/0, 2-byte register msb lsb msb lsb d7 d6 d5 d4 d3 d2 d1 d0 tens bcd units bcd page number of the received page msb lsb lsb d7 d6 d5 d4 d3 d2 d1 d0 magazine number msb row number of the page header (=0) of the received page 8.2. the control bit register 1, r-cb1 address x/25/2, 1-byte register msb lsb d7 d6 d5 d4 d3 d2 d1 d0 units bcd minutes of time code tens bcd c 4 c 4 clear page: c 4 0 1 clears row flags and makes bxt=pah=1 8.3. the control bit register 2, r-cb2 address x/25/3, 1-byte register c 5 c 6 lsb msb lsb d7 d6 d5 d4 d3 d2 d1 d0 units bcd msb hours of time code tens bcd c 5 : newsflash c 6 : subtitle only boxed information is displayed and superimposed on a tv picture. 8.4. the control bit register 3, r-cb3 address x/25/4, 1-byte register c 7 c 8 c 9 c 10 c 11 c 12 c 13 d7 d6 d5 d4 d3 d2 d1 d0 c 14 c 14 : language selection (see r-dc5) c 13 : language selection (see r-dc5) c 12 : language selection (see r-dc5) c 11 : serial magazine mode c 10 : inhibit teletext: inhibits the display of page c 9 : out of sequence: this header is not used for the rolling-header display c 8 : update: c 8 0 1 makes bxt=pah=1 c 7 : suppress header: this header is not displayed the function of c7 is influenced by the ano header sup- pressiono (nhs) control bit in register r_dc4 of register chain 2. also the adisplay page headero (pah) control bit in register r_dc1 of rc2 overwrites c7. note that pah is set every time the page is updated, and must be reset to enable the function of c7.
tpu 2735 29 8.5. the row flag register, r-rfx address x/25/5, 6-byte register r7 r4 r3 r0 d7 d6 d5 d4 d3 d2 d1 d0 r6 r5 r2 r1 r15 r12 r11 r8 r14 r13 r10 r9 r23 r20 r19 r16 r22 r21 r18 r17 rr7 rr4 rr3 rr0 rr6 rr5 rr2 rr1 rr15 rr12 rr11 rr8 rr14 rr13 rr10 rr9 rr23 rr20 rr19 rr16 rr22 rr21 rr18 rr17 a row flag is set to 1 by the tpu if the corresponding row has been received. when a new page is received, all row flags of the corresponding sector are cleared. the display unit displays only those rows whose row flags are 1. the registers x/25/8 to x/25/10 contain the right-hand- side row flags which are used in ntsc mode. they con- trol the display of the last 8 character positions of each row which are transmitted in separate lines. in pal/d2mac mode some of the right-hand side row flags are used when the flof or ecs bits are active: rowflag rr0: controls display of row x/24. this flag is un- der software control rowflag rr4: indicates reception of a row x/27 and is set/ reset by tpu rowflag rr8: indicates reception of one or more rows x/26, set/reset by tpu 8.6. the timing of the register chains the contents of the register chains 1 and 2 is updated in the tpu only once per field. this is important for a command sequence with commands which rely on the execution of preceding commands, e. g. aa clear displayo command followed by new display data. in this example a pause of 2 fields is necessary before the new data is written into the ram: one field for the tpu to recognize the clear command and another field to execute this command. 9. two ways to select a page for display first way load the selected page number into r-ps and set sic = 1; if the page number has already been requested, r-ds is loaded automatically with the according sector number and rps is set to 1; if rps remains 0, the ccu has to load one of the eight r-pr 0 to 7 with this page number. second way the ccu compares the selected page number with the contents of r-pr 0 to 7; if the page number is not found in r-pr 0 to 7, one register of r-pr 0 to 7 has to be loaded with the selected page number. the ccu loads the number of the selected sectors into r-ds. the r-ps register and sic control bit are kept for com- patibility with tpu 2732. for new software the second way for page selection is recommended. 10. reset of the tpu 2735 teletext processor the power-up reset makes ttm = 0 (no teletext mode) and cr 2 = 1 (clear register chain 2). a software reset is achieved by setting cr 2 = 1.
tpu 2735 30 11. application notes problem: clamping of external rgb signals the external rgb inputs are fed through the tpu to the vcu. clamping of these signals is done by the vcu dur- ing the color key pulse. the rgb switches of the tpu are controlled by the external afast blanko input to the tpu and by internal control bits (ttm, rgbe, please re- fer to sections 3.3., 6.4.). in some cases the external fast blank signal is switched off during the horizontal blank- ing interval (e.g. pip insertion and osd active). in these cases the external rgb inputs are not switched to the vcu during the blanking interval and the clamping fails. to force clamping of the rgb inputs in all modes the col- or key should be `ored' to the external fast blank signal. problem: conflict flag the conflict flag in the page request register is set if the tpu273x has opened a page for acquisition and re- ceives a header row for another page that is requested in some other request register. this usually happens when the last page of a magazine is requested. in the case of a conflict the internal logic of the tpu assigns the highest priority to the page selected for display. setting the `no updating' flag for this page will resolve the con- flict. (in order to get an `open' page into nuf mode one should set nup and nrf.) also the behavior of the ac- quisition circuit is influenced by the open (opn) bit in the page selection register. this bit forces the acquisition circuit to keep pages open and thereby makes conflict situations worse. this bit should be zero for normal tele- text acquisition. continuous long updating times for the `time' field are also influenced by the conflict. the world system teletext specification reserves a row0 of page 0x?ff (hexadecimal) for the function of magazine close row. transmitting this row would solve all of these problems. problem: spanish teletext as the decoding of the information transmitted in rows 26 is done by the ccu obviously the control program has to check for the reception of any row26. the actual row26 processing is only required for the page currently displayed. this should be done in the `idle loop' of the control program. there is no other way than polling to see if a row26 was received. the `spanish teletext specification' requires the extra characters to be transmitted with even parity. therefore a true `spanish teletext page' cannot be received with- out errors and will be acquired again and again. (it is not recommended to use the npc mode.) a way to detect the reception of a `new' (i.e. different) page is to check the subcode information stored in register chain one. usually a subcode of all zeros or all ones indicates a non-rolling page. problem: initialization initialization of the tpu should always start with a clear of register chain 2 via the cr2 bit in the r_mc register. if the mode is switched to ntsc/d2mac, setting the ap- propriate control bit in register r_dc4 should be the next action. since internal clocks of the tpu are switched by these bits, the next thing should be a clear of all registers in register chain 2 (except the mode regis- ter r_dc4). in case of ntsc mode, it is recommended to set the ntsc bit, wait for two fields, check that the ntsc bit is still set, and then start the clearing of register chain 2. after this procedure the normal initialization of registers should follow. samples for TPU2735-e are available and are marked TPU2735-tc18. the logic of these samples is identical to TPU2735-tc15.
tpu 2735 31 data sheet update: ecs in ecs mode the tpu acquires teletext rows x/26. the memory organization is changed in order to store the row x/26 for each sector (ref. to section 5). two addition- al control characters a0x0: alpha blacko and a0x10: mo- saic blacko are processed. additional characters for the spanish teletext system are provided (ref. fig. 111). these characters overlay the control characters with bit 7 (msb) set. fig. 111: extended character set for spanish teletext system ? ? ? ?. a ? ? ?? ? ?? ?? a o # ? 01 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
tpu 2735 32 TPU2735-e character set for eastern europe appli- cation TPU2735 will be available with a character set for east- ern european countries. this version of TPU2735 will be designated TPU2735-e. the only logic changes are for control of character sets via register r-dc5 in register chain 2. an ntsc character set will not be supported by TPU2735-e, the uks bit in r-dc5 allows to select two different character set assignments. character set assignments register r-dc5 ls uks=0 uks=1 0 english polish 1 german german 2 swedish hungarian 3 italian italian 4 french french 5 polish polish 6 turkish turkish 7 rumanian rumanian 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 english german french italian polish turkish swedish/ hungarian rumanian standard g0 character set 2 3 4 5 6 7 0 1 ecs character set fig. 112: tpu 2735-e character set for eastern europe application 2/3 2/4 4/0 5/11 5/12 5/13 5/14 5/15 6/0 7/11 7/12 7/13 7/14
tpu 2735 33 12. description of the im bus the intermetall bus (im bus for short) was de- signed to control the digit 2000 ics by the ccu central control unit. via this bus the ccu can write data to the ics or read data from them. this means the ccu acts as a master whereas all controlled ics are slaves. the im bus consists of three lines for the signals ident (id), clock (cl) and data (d). the clock frequency range is 50hz to 170 khz. ident and clock are unidirec- tional from the ccu to the slave ics, data is bidirec- tional. bidirectionality is achieved by using open-drain outputs with on-resistances of 150 w maximum. the 2.5 k w pull-up resistor common to all outputs is incorporated in the ccu. the timing of a complete im bus transaction is shown in fig. 121 and table 121. in the non-operative state the signals of all three bus lines are high. to start a transac- tion the ccu sets the id signal to low level, indicating an address transmission, and sets the cl signal to low level as well to switch the first bit on the data line. there- after eight address bits are transmitted beginning with the lsb. data takeover in the slave ics occurs at the positive edge of the clock signal. at the end of the ad- dress byte the id signal goes high, initiating the address comparison in the slave circuits. in the addressed slave the im bus interface switches over to data read or write, because these functions are correlated to the address. also controlled by the address the ccu now transmits eight or sixteen clock pulses, and accordingly one or two bytes of data are written into the addressed ic or read out from it, beginning with the lsb. the completion of the bus transaction is signalled by a short low-state pulse of the id signal. this initiates the storing of the transferred data. it is permissible to interrupt a bus transaction for up to 10 ms.
tpu 2735 34 table 121: timing of the im bus signals time t im1 t im2 t im3 t im4 t im5 t im6 t im7 t im8 t im9 t im10 min. m s 0 3.0 3.0 0 1.5 6.0 0 0 0 3.0 fig. 121: im bus waveforms h l h l h l ident clock data 12 34 678910111213 16 or 24 lsb address msb lsb data msb ab c section a section b section c h l data h l clock h l ident address lsb address msb data msb 5 t im1 t im3 t im2 t im7 t im8 t im9 t im4 t im5 t im6 t im10
tpu 2735 35
tpu 2735 36 itt semiconductors group world headquarters intermetall hans-bunte-strasse 19 d-79108 freiburg (germany) p.o. box 840 d-79008 freiburg (germany) tel. +49-761-517-0 fax +49-761-517-2174 printed in germany by simon druck gmbh & co., freiburg (01/93) order no. 6251-312-4e reprinting is generally permitted, indicating the source. how- ever, our consent must be obtained in all cases. information furnished by itt is believed to be accurate and reliable. how- ever, no responsibility is assumed by itt for its use; nor for any infringements of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of itt. the informa- tion and suggestions are given without obligation and cannot give rise to any liability; they do not indicate the availability of the components mentioned. delivery of development samples does not imply any obligation of itt to supply larger amounts of such units to a fixed term. to this effect, only written confirma- tion of orders will be binding.
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