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data bulletin cmx808a ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. family radio service ctcss processor preliminary information features rapid multi-tone ctcss decoder supports new end user features fast tone decode (150ms) supports tones from 62.5hz to 251hz integrated 32 step digital volume control (-48.0db to 0db + off) tone cloning capabilities sub-audio tone rejection filter low power 3.0v to 5.5v operation very small 20-pin tssop package 4.0mhz xtal/clock oscillator applications family radio service (frs) radios amateur radio equipment general mobile radio service (gmrs) short range business radio modulator discriminator host c keypad display radio cmx808a rf tx serial 'c-bus' data & control rx fast ctcss audio filter volume control the cmx808a is a programmable ctcss encoder/decoder optimized for family radio service transceivers through a combination of leading edge performance, low cost, small size, and low power. with rapid response time and the ability to decode one-of-many possible tones, the decoder enables practical tone scanning to allow an frs radio to quickly decode received ctcss tones by 'listening' to the ctcss tone transmissions of other frs radios. this feature can be used to: 1. readily support both individual (one person) and group (e.g. children vs. adults) call codes. 2. support quick and automatic resolution of radio user frustration caused by mismatched ctcss tone configurations in ctcss-based frs radios. in some cases, this approach can be used to match ctcss tone decoder configurations to different vendors' ctcss-based frs radios when supported tone sets are not clearly documented or well understood. with integrated digital volume control and a simple serial control interface, the cmx808a features very low power consumption and small size. the cmx808a requires a 3.0v to 5.5v power supply and is available in the following packages: 20-pin tssop (cmx808ae3) and 24-pin pdip (CMX808AP4).
family radio service ctcss processor 2 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. contents section page 1 block diagram................................................................................................................ 3 2 signal list................................................................................................................... .... 4 3 external components.................................................................................................... 6 4 general description....................................................................................................... 7 4.1 software description ........................................................................................................ ... 7 4.1.1 address/commands.......................................................................................................... ..... 7 4.1.2 write only register description ........................................................................................... .. 7 4.1.3 read only register description ........................................................................................... 1 2 5 application notes ........................................................................................................ 15 5.1 general..................................................................................................................... ......... 15 5.2 transmitter ................................................................................................................. ....... 15 5.3 tx tone table ............................................................................................................... .... 16 5.4 receiver (decode)........................................................................................................... .. 16 5.5 rx tone table ............................................................................................................... .... 17 6 performance specification.......................................................................................... 18 6.1 electrical performance ...................................................................................................... 18 6.1.1 absolute maximum ratings.................................................................................................. 18 6.1.2 operating limits .......................................................................................................... ......... 18 6.1.3 operating characteristics................................................................................................. .... 19 6.1.4 timing diagrams ........................................................................................................... ....... 21 6.2 packaging................................................................................................................... ....... 22 mx-com, inc. reserves the right to change specification at any time and without notice.
family radio service ctcss processor 3 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 1 block diagram clock oscillator and dividers sub audio lpf audio filter ctcss tx tone generator 'c-bus' interface and control logic a to d converter ctcss tone decoder v bias v ss v dd c6 c4 tx audio in tx audio input r1 - + ctcss tx audio tx / rx rx amp enable v bias rxampout rxampin c3 xtal xtal/clock c5 r3 r4 c7 input from demodulator c1 c2 x1 c8 a/d cap ctcss rx tx sub audio out tx audio out rx audio out volume out command data reply data cs irq serial clock v dd r2 enable volume control volume in figure 1: block diagram
family radio service ctcss processor 4 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 2 signal list package / pin no signal e3 p4 name type description 11 xtal output the inverted output of the on-chip oscillator. 2 2 xtal/clock input the input to the on-chip oscillator, for external xtal circuit or clock. 3 3 serial clock input the "c-bus" serial clock input. this clock, produced by the c, is used for transfer timing of commands and data to and from the device. see figure 6. 4 4 command data input the "c-bus" serial data input from the c. data is loaded into this device in 8-bit bytes, msb (d7) first, and lsb (d0) last, synchronized to the serial clock. see figure 6. 5 5 reply data output the "c-bus" serial data output to the c. the transmission of reply data bytes is synchronized to the serial clock under the control of the cs input. this 3-state output is held at high impedance when not sending data to the c. see figure 6. 66 cs input the "c-bus" data loading control function: this input is provided by the c. data transfer sequences are initiated, completed or aborted by the cs signal. see figure 6. 77 irq output this output indicates an interrupt condition to the c by going to a logic "0". this is a "wire-orable" output, enabling the connection of up to 8 peripherals to 1 interrupt port on the c. this pin has a low impedance pulldown to logic "0" when active and a high-impedance when inactive. an external pull-up resistor is required. an interrupt is effective if not masked out by the irq mask (bit 0 in the sub-audio control register $80). 88 nc 9nc no internal connection. do not make any connection to these pins. 9 10 a/d cap output an internal reference voltage for the a to d converter, decoupled to v ss by an external capacitor. 11 nc no internal connection. do not make any connection to this pin. 10 12 v ss power the negative supply rail (ground). 11 13 v bias output a bias line for the internal circuitry, held at v dd /2. this pin must be decoupled by a capacitor mounted close to the device pins. 12 14 rx amp in input the inverting input to the rx input amplifier. 13 15 rx amp out output the output of the rx input amplifier and the input to the audio filter section. 14 16 rx audio out output output of the rx audio filter section. 17 nc no internal connection. do not make any connection to this pin. 15 18 tx audio in input input to the tx audio filter section. 16 19 tx audio out output output of the tx audio filter section. 17 20 volume in input input to the audio volume control. 18 21 tx sub audio out output output of the ctcss tone generator. 19 22 volume out output output of the audio volume control.
family radio service ctcss processor 5 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. package / pin no signal e3 p4 name type description 23 nc no internal connection. do not make any connection to this pin. 20 24 v dd power the positive supply rail. levels and voltages are dependent upon this supply. this pin should be decoupled to v ss by a capacitor. table 1: signal list
family radio service ctcss processor 6 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 3 external components v dd v dd v ss v dd v bias irq xtal a/d cap serial clock "c-bus" interface command data xtal/clock rx amp in r3 r4 r2 input from demodulator tx audio input cmx808ae3 tx sub audio out c4 c8 c5 c3 c7 c6 reply data cs nc rx amp out rx audio out volume out volume in tx audio in tx audio out 1 2 3 4 5 6 8 9 10 11 12 13 14 7 20 19 18 17 16 15 xtal xtal/clock c1 c2 x1 r1 figure 2: recommended external components r1 1m : 5% c4 0.1f 20% r2 22k : 10% c5 100pf 20% r3 100k : 10% c6 0.1f 20% r4 note 1 10% c7 note 1 20% c1 22pf 20% c8 0.1f 20% c2 22pf 20% c3 0.1f 20% x1 note 2 4.0mhz 100ppm table 2: recommended external components recommended external component notes: 1. r3, r4, c5 and c7 form the gain components for the rx input amplifier. r4 should be chosen as required by the signal level, using the following formula: r4 r3 - gain = c7 x r4 should be chosen so as not to compromise the low frequency performance of this product. 2. for best results, a crystal oscillator design should drive the clock inverter input with signal levels of at least 40% of v dd , peak to peak. tuning fork crystals generally cannot meet this requirement. to obtain crystal oscillator design assistance, please consult your crystal manufacturer.
family radio service ctcss processor 7 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 4 general description the cmx808a is a programmable ctcss processor for family radio service, see figure 1. the receiver of the cmx808a decodes a user-programmable set of up to 7 tones with minimum software intervention; the band-pass filter is designed to filter out the ctcss sub-audio tones. a high-resolution tone encoder performs accurate generation of ctcss tones. each function, and the routing of signals, is flexible and may be configured or controlled by the user's software. 4.1 software description 4.1.1 address/commands instructions and data are transferred, via "c-bus", in accordance with the timing information given in figure 6. instruction and data transactions to and from the cmx808a consist of an address/command (a/c) byte, which may be followed by either: (i) a further instruction or data (1 or 2 bytes) or (ii) a status or rx data reply (1 byte) 4.1.2 write only register description hex address/ command register name bit 7 (d7) bit 6 (d6) bit 5 (d5) bit 4 (d4) bit 3 (d3) bit 2 (d2) bit 1 (d1) bit 0 (d0) $01 general reset n/a n/a n/a n/a n/a n/a n/a n/a ctcss ctcss decoder bandwidth $80 sub-audio control tx enable decoder enable msb bit 3 bit 2 bit 1 lsb bit 0 0 ctcss irq mask audio attenuation $82 audio control tx bpf enable rx bpf enable bpf un- mute msb bit 4 bit 3 bit 2 bit 1 lsb bit 0 table 3: 8-bit write only registers hex address/ command register name bit 7 (d7) bit 6 (d6) bit 5 (d5) bit 4 (d4) bit 3 (d3) bit 2 (d2) bit 1 (d1) bit 0 (d0) ctcss tx frequency ctcss tx freq. (byte 1) ctcss tx notone 00 msb bit 12 bit 11 bit 10 bit 9 bit 8 ctcss tx frequency $83 ctcss tx freq. (byte 2) bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 lsb bit 0 ctcss tone address ctcss frequency ctcss rx program (byte 1) 0 msb bit2 bit 1 lsb bit 0 msb bit 11 bit 10 bit 9 bit 8 ctcss frequency $84 ctcss rx program (byte 2) bit 7 bit6 bit 5 bit 4 bit 3 bit 2 bit 1 lsb bit 0 table 4: 16-bit write only registers 4.1.2.1 general reset (hex address $01) the reset command has no data attached to it. it sets the device registers to zero (all powersaved) with the exception of bits 2, 1 and 0 of the sub-audio status register $81.
family radio service ctcss processor 8 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 4.1.2.2 sub-audio control register (hex address $80) this register is used to control the functions of the device as described below: ctcss tx enable and decoder enable (bits 7 and 6) these two bits enable and disable the ctcss decoder (rx) or transmitter (tx) according to table 6. ctcss decoder bandwidth (bits 5, 4, 3 and 2) these four bits set the bandwidth of the ctcss tone decoder according to table 7. (bit 1) reserved for future use. this bit should be set to "0". ctcss irq mask (bit 0) when this bit is set to "1" it enables the interrupt. when this bit is set to "0" the interrupt is masked. table 5: sub-audio control register (hex address $80) tx (bit 7) rx (bit 6) function 0 0 tx disabled, rx disabled 0 1 tx disabled, rx enabled 1 0 tx enabled, rx disabled 1 1 tx enabled, rx enabled table 6: ctcss tx enable and decoder enable bandwidth bit 5 bit 4 bit 3 bit 2 will decode will not decode 1000 1.1% 2.4% 1001 1.3% 2.7% 1010 1.6% 2.9% 1011 1.8% 3.2% 1100 2.0% 3.5% 1101 2.2% 3.7% 1110 2.5% 4.0% 1111 2.7% 4.2% table 7: ctcss decoder
family radio service ctcss processor 9 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 4.1.2.3 audio control register (hex address $82) this register is used to control the functions of the device as described below: note: tx bpf enable (bit 7) and rx bpf enable (bit 6) should not be enabled at the same time. tx bpf enable (bit 7) when this bit is "1" the audio band-pass filter is enabled and the output of the filter is switched to tx audio out. the output is then controlled by bpf un- mute. see bit 5 below. when this bit is 0 the audio band pass filter is disabled (powersaved) and the output of the filter is disconnected from tx audio out, which is then in a high impedance state. rx bpf enable (bit 6) when this bit is 1 the audio band-pass filter is enabled and the output of the filter is switched to rx audio out. the output is then controlled by bpf un- mute. see bit 5 below. when this bit is 0 the audio band-pass filter is disabled (powersaved) and the output of the filter is disconnected from rx audio out, which is then in a high impedance state. bpf un-mute (bit 5) when this bit is 1 and tx bpf enable is 1 the audio band-pass filter output is switched to the tx audio out pin. when this bit is 0 the output of the filter is disconnected from tx audio out, which is then in a high impedance state. this control, along with tx bpf enable, allows the filter to power up and settle internally before switching the output on, when coming out of powersave. when this bit is 1 and rx bpf enable is 1 the audio band-pass filter output is switched to the rx audio out pin. when this bit is 0 the output of the filter is disconnected from rx audio out, which is then in a high impedance state. this control, along with rx bpf enable, allows the filter to power up and settle internally before switching the output on, to avoid clicks when coming out of powersave. audio attenuation (bits 4, 3, 2, 1, and 0) these five bits are used to set the attenuation of the audio volume control according to table 9. table 8: audio control register (hex address $82) bits audio 43210attenuation 0 0 0 0 0 off (v bias ) 0 0 0 0 1 48.0db 0 0 0 1 0 46.4db 0 0 0 1 1 44.8db 0 0 1 0 0 43.2db 0 0 1 0 1 41.6db 0 0 1 1 0 40.0db 0 0 1 1 1 38.4db 0 1 0 0 0 36.8db 0 1 0 0 1 35.2db 0 1 0 1 0 33.6db 0 1 0 1 1 32.0db 0 1 1 0 0 30.4db 0 1 1 0 1 28.8db 0 1 1 1 0 27.2db 0 1 1 1 1 25.6db
family radio service ctcss processor 10 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. bits audio 43210attenuation 1 0 0 0 0 24.0db 1 0 0 0 1 22.4db 1 0 0 1 0 20.8db 1 0 0 1 1 19.2db 1 0 1 0 0 17.6db 1 0 1 0 1 16.0db 1 0 1 1 0 14.4db 1 0 1 1 1 12.8db 1 1 0 0 0 11.2db 11001 9.6db 11010 8.0db 11011 6.4db 11100 4.8db 11101 3.2db 11110 1.6db 11111 0db table 9: audio attenuation 4.1.2.4 ctcss tx frequency register (hex address $83) this is a 16-bit register. byte (1) is sent first. when the ctcss transmitter is enabled, the bits 0 to 12 control the frequency of the transmitted ctcss tones according to the formula below. a f (hz) 16 x f (hz) xtal tone = where a is the binary number programmed into the 13 bits. when bit 7 (in the first 8 bits) is set to "1" the tone output is set at v bias or notone without regard to the number "a" programmed. when bit 7 is "0" the programmed tone is set on the output. programming bits 0 to 12 to "0" sets the output to v bias . powersave is achieved by disabling the tx (bit 7 in the sub-audio control register $80).
family radio service ctcss processor 11 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 4.1.2.5 ctcss rx program register (hex address $84) this is a 16-bit register. byte (1) is sent first. the two bytes are used to program the center frequencies of up to 7 tones in the sub-audio band that will be decoded by the receiver. each tone is identified by its address in bits 6, 5 and 4 of byte (1). the remaining 12 bits contain the data representing the tone frequency according to the formula below. if a tone is not required, the 12 bits should be set to zero. byte 1 byte 2 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 0000 0001 0010 0011 0100 0101 0110 <----------------------- n -----------------------> n is the binary representation of the following decimal number (n): ? ? ? ? ? = xtal tone f f 948982 int n <----------------------- r -----------------------> r is the nearest 6-bit binary representation of (r), where: 8400 f 4 n f 237245 r tone xtal ? ? ? ? ? - = example: to program 100hz when using the recommended 4.0mhz xtal. () (binary) 001111 r 15 r halfway) exactly if up (round 21 . 15 r 8400 100 4 23 10 0 . 4 237245 r (binary) 010111 n 23 72 . 23 int n 10 0 . 4 100 948982 int n 6 6 = \ = = ? ? ? ? - = = \ = = ? ? ? ? = therefore the 12-bit code is 010111001111. the hex address represented by bits 6, 5 and 4 in byte (1) is used as the code to indicate which tone has been decoded. this code appears in bits 2, 1 and 0 of the sub-audio status register $81. the seven programmed tones use hex addresses $0 - $6. address $7 should not be used. 4.1.2.6 tone cloning (hex address $9c) this register enables and disables tone cloning as shown below: $9c = $01 enables tone cloning $9c = $00 disables tone cloning the tone cloning routine is shown in figure 4.
family radio service ctcss processor 12 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 4.1.3 read only register description hex address/command register name bit 7 (d7) bit 6 (d6) bit 5 (d5) bit 4 (d4) bit 3 (d3) bit 2 (d2) bit 1 (d1) bit 0 (d0) ctcss rx tone $81 sub-audio status 00 0 0 tone decode msb bit 2 bit 1 lsb bit 0 table 10: 8-bit read only registers 4.1.3.1 sub-audio status register (hex address $81) reading the sub-audio status register clears the interrupt ( irq ). this register is used to indicate the status of the device as described below: (bits 7, 6, 5 and 4) reserved for future use. these will be set to "0" but should be ignored by user's software. tone decode (bit 3) this bit indicates the status of the tone decoder. a "1" indicates a tone has been detected (tone decode) and a "0" indicates the loss of the tone (notone). tone decode means that a tone has been decoded and its characteristics are defined by the bandwidth (see sub-audio control register $80, bits 5, 4, 3 and 2) and the ctcss rx tone number (see sub-audio status register $81, bits 2, 1 and 0). when bit 6 in the sub-audio control register $80 is set to "0" the tone decode bit 3 will be set to "0". identification of a valid tone which is not in the pre-programmed list of up to 7 tones will cause the decoder to move to the tone decode state with the rx tone address of "111" in bits 2, 1 and 0; indicating a valid but unrecognized tone. loss of tone will cause the notone timer to be started. if loss of tone continues for the duration of the time- out period, then the decoder will move to notone state and the identification of pre- programmed tones will start again. the time-out period is not user adjustable. ctcss rx tone (bits 2, 1 and 0) these three bits hold a hex number. numbers $0 to $6 represent the address of the ctcss tone decoded according to the tones programmed in the ctcss rx program register $84. the hex number $7 indicates the presence of any tone that is not described by ctcss decoder bandwidth (bits 5, 4, 3 and 2 in the sub-audio control register $80) and ctcss frequency (bits 11 to 0 in the ctcss rx program register $84).
family radio service ctcss processor 13 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 4.1.3.2 tx/rx enabled set-up example power up clear registers $01 rx or tx? tx (100hz) rx (address 0, 100hz, 2.7% bandwidth, irq enabled) program 100hz into address 0 $84 (1) = 00000101 $84 (2) = 11001111 program bandwidth to 2.7% enable irq mask enable decoder $80 = 01111101 enable tx $80 = 10000000 program tx frequency to 100hz $83 (1) = 00001001 $83 (2) = 11000100 note: $8x is the hex address/command figure 3: tx/rx enabled
family radio service ctcss processor 14 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 4.1.3.3 tone cloning routine the flow chart shows the tone cloning routine. the first programmed tone set ($0-$6) will decode after typically 140ms, subsequent tone sets will decode almost instantly (i.e. the information is available at the reply data output in less than 100 m s). note: $8x and $9c is the hex address/command enable tone cloning $9c=$01 wait for interrupt read status register ($81) is it a programmed tone? tone decoded ye s no mask interrupt $80=$7c program tones ($84) into addresses $0-$6 read status register ($81) no ye s tone decoded program bandwidth enable irq mask enable decoder $80=$7d is it a programmed tone? program tones ($84) into addresses $0-$6 wait 100s figure 4: tone cloning routine
family radio service ctcss processor 15 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 5 application notes 5.1 general the cmx808a is intended for use in radio systems where subaudio tone signaling is required for functions such as family radio service (frs) hand-helds, amateur radio equipment, general mobile radio service (gmrs) and short range business radio. the facility to decode any one of 7 programmed tones (or one-of-any if tone sets are dynamically reconfigured) allows designers to offer attractive end features to: simultaneously support multiple calling tone codes e.g. children, parents and family with unique paging and/or visual alerts used to identify each calling party or group. effectively scan and 'learn' received tones to make rx tone configuration easy and nearly automatic. configurable decoder bandwidths provide the flexibility to optimize performance under different operating conditions such as when congestion or long distances alter signal quality. 5.2 transmitter the transmitter is enabled with bit 7 in the sub-audio control register $80. the tx frequency is set using bits 0 to 12 in the ctcss tx frequency register $83, using the formula below: ) hz ( f 16 ) hz ( f a tone xtal = where a is the binary number programmed into the 13 bits. when bit 7 (in the first 8 bits) is set to "1" the tone output is set at v bias or notone without regard to the number "a" programmed. when bit 7 is "0" the programmed tone is set on the output. programming bits 0 to 12 to "0" sets the output to v bias . powersave is also achieved by disabling the tx (bit 7 in the sub-audio control register $80).
family radio service ctcss processor 16 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 5.3 tx tone table the following table lists the commonly used ctcss tones and the corresponding values for programming the ctcss tx frequency register $83. standard tones freq. byte 1 byte 2 freq. byte 1 byte 2 freq. byte 1 byte 2 (hz) (hex) (hex) (hz) (hex) (hex) (hz) (hex) (hex) 67.0 0e 93 103.5 09 6f 162.2 06 05 69.3 0e 18 107.2 09 1c 167.9 05 d1 71.9 0d 95 110.9 08 ce 173.8 05 9e 74.4 0d 20 114.8 08 82 179.9 05 6e 77.0 0c af 118.8 08 38 186.2 05 3f 79.7 0c 41 123.0 07 f1 192.8 05 11 82.5 0b d6 127.3 07 ac 203.5 04 cd 85.4 0b 6f 131.8 07 69 210.7 04 a3 88.5 0b 09 136.5 07 28 218.1 04 7a 91.5 0a ac 141.3 06 e9 225.7 04 54 94.8 0a 4d 146.2 06 ae 233.6 04 2e 97.4 0a 07 151.4 06 73 241.8 04 0a 100.0 09 c4 156.7 06 3b 250.3 03 e7 non-standard tones freq. byte 1 byte 2 freq. byte 1 byte 2 freq. byte 1 byte 2 (hz) (hex) (hex) (hz) (hex) (hex) (hz) (hex) (hex) 62.5 0f a0 183.5 05 52 199.5 04 e5 64.7 0f 18 189.9 05 24 206.5 04 bb 159.8 06 1c 196.6 04 f8 229.1 04 43 5.4 receiver (decode) the ctcss receiver (decoder) should first be set up according to the desired characteristics. this entails setting the ctcss decoder bandwidth in the sub-audio control register $80, also programming the center frequencies of the desired tones in the ctcss rx program register $84. (it can hold up to 7 different tones). any tone can be in any location. during operation when the device is receiving, the tones are scanned in the sequence of their location, i.e. $0 first and $6 last and once a tone is detected the remaining tones are not checked. therefore, if two tones are close enough in frequency for their bandwidths to overlap then the one in the lowest location will be detected. the ctcss irq mask in the sub-audio control register $80 should also be set as required. the ctcss decoder enable in the sub-audio control register $80 should then be set to "1". the tone cloning register $9c should be set as required. when the receiver detects a change in its present state an interrupt will be generated. the change that occurred can be read from bit 3 of the sub-audio status register $81 and if a tone is indicated by these bits then the number of that tone can be read from bits 2, 1 and 0 of the same register. the interrupt is cleared by reading the sub-audio status register.
family radio service ctcss processor 17 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 5.5 rx tone table the following table lists the commonly used ctcss tones together with the values for programming the ctcss rx program register $84 for tone address 0. (tone addresses 1 to 6 are also available.) other tones within the supported tone range can also be configured as described in section 4.1.2.5. note: the most significant nibble (four bits) of byte 1 determines the tone register address being configured and is independent of the configured tone frequency. for example, this nibble (left hex character of byte 1) is set to $0 (hex), corresponding to tone address 0, for all entries in the table below. as another example the same tone table for tone address 5 would require this nibble to be set to $5 (hex) for all values in the table e.g. 67.0hz would be $53 (byte 1) $dc (byte 2). standard tones freq. byte 1 byte 2 freq. byte 1 byte 2 freq. byte 1 byte 2 (hz) (hex) (hex) (hz) (hex) (hex) (hz) (hex) (hex) 67.0 03 dc 103.5 06 0b 162.2 09 86 69.3 04 0d 107.2 06 48 167.9 09 ca 71.9 04 42 110.9 06 86 173.8 0a 43 74.4 04 52 114.8 06 c4 179.9 0a 88 77.0 04 87 118.8 07 03 186.2 0b 02 79.7 04 98 123.0 07 43 192.8 0b 48 82.5 04 cf 127.3 07 83 203.5 0c 03 85.4 05 06 131.8 07 c4 210.7 0c 4a 88.5 05 18 136.5 08 06 218.1 0c c7 91.5 05 50 141.3 08 48 225.7 0d 45 94.8 05 8b 146.2 08 8a 233.6 0d c4 97.4 05 c2 151.4 08 cd 241.8 0e 43 100.0 05 cf 156.7 09 42 250.3 0e c3 non-standard tones freq. byte 1 byte 2 freq. byte 1 byte 2 freq. byte 1 byte 2 (hz) (hex) (hex) (hz) (hex) (hex) (hz) (hex) (hex) 62.5 03 9c 183.5 0a c6 199.5 0b c3 64.7 03 cb 189.9 0b 41 206.5 0c 0a 159.8 09 4c 196.6 0b 87 229.1 0d 83
family radio service ctcss processor 18 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6 performance specification 6.1 electrical performance 6.1.1 absolute maximum ratings exceeding these maximum ratings can result in damage to the device. min. max. units supply (v dd - v ss ) -0.3 7.0 v voltage on any pin to v ss -0.3 v dd + 0.3 v current into or out of: v dd -30 +30 ma v ss -30 +30 ma any other pin -20 +20 ma e3 package total allowable power dissipation at t amb = 25c 300 mw derating above 25c 5 mw/c above 25c storage temperature -55 +125 c operating temperature -40 +85 c p4 package total allowable power dissipation at t amb = 25c 800 mw derating above 25c 13 mw/c above 25c storage temperature -55 +125 c operating temperature -40 +85 c 6.1.2 operating limits correct operation of the device outside these limits is not implied. notes min. max. units supply (v dd - v ss )3.05.5v operating temperature -40 85 c xtal frequency 3.9996 4.0004 mhz
family radio service ctcss processor 19 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.1.3 operating characteristics for the following conditions unless otherwise specified: xtal frequency = 4.0mhz, audio level 0db ref. = 308mv rms at 1khz v dd = 3.0v to 5.0v, t amb = -40c to +85c, composite signal = 308mv rms at 1khz + 75mv rms noise + 31mv rms sub-audio signal noise bandwidth = 5khz band limited gaussian notes min. typ. max. units dc parameters at v dd = 3.0v i dd (powersaved) 2 0.2 0.3 ma i dd (encoder or decoder only operating) 2 1.3 2.0 ma at v dd = 5.0v i dd (powersaved) 2 0.5 0.8 ma i dd (encoder or decoder only operating) 2 3.2 4.8 ma "c-bus" interface input logic "1" 70% v dd input logic "0" 30% v dd input leakage current (logic "1" or "0") -1.0 1.0 a input capacitance 7.5 pf output logic "1" (i oh = 120a) 90% v dd output logic "0" (i ol = 360a) 10% v dd "off" state leakage current (v out = v dd ) 3 10.0 a ac parameters ctcss decoder sensitivity (pure ctcss tone) 5 -26.0 db response time (composite signal) 140 ms de-response time (composite signal) 145 ms frequency range 60.0 251 hz ctcss encoder frequency range 60.0 251 hz tone frequency resolution 0.3 % tone amplitude tolerance 1 -1.0 0 1.0 db total harmonic distortion 3.0 % audio band-pass filter passband 6 350 3000 hz passband gain (at 1.0khz) 6 - 0 db passband ripple (with respect to gain at 1.0khz) 6 -2.0 +0.5 db stopband attenuation 6 30.0 db residual hum and noise -50.0 dbp alias frequency 62.5 khz audio attenuator nominal adjustment range 0 48 db attenuation accuracy -1.5 1.5 db step size 1.6 db
family radio service ctcss processor 20 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. notes min. typ. max. units output impedances tx sub-audio out (enabled) 2.0 k w tx/rx audio out (enabled) 600 w tx/rx audio out (disabled) 500 k w volume out (enabled) 7 600 w rx amplifier open loop gain (input = 1mv at 100hz) 70.0 db unity gain bandwidth 5.0 mhz input impedance (at 100hz) 10.0 m w output impedance (open loop) 6.0 k w xtal/clock input pulse width ('high' or 'low') 4 40.0 ns input impedance (at 100hz) 10.0 m w gain (input = 1mv rms at 100hz) 20.0 db notes: 1. at v dd = 5.0v only. signal levels or currents are proportional to v dd . 2. not including any current drawn from the device pins by external circuitry. 3. irq pin. 4. timing for an external input to the xtal/clock pin. 5. with input gain components set as recommended in figure 2. 6. see filter response (figure 5). 7. small signal impedance v dd = 5.0v and t amb = 25c. a minimum load resistance of 6k w is suggested. -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 100 1,000 10,000 100,000 frequency (hz) gain (db) 350hz 250hz 3khz figure 5: audio band-pass filter frequency response
family radio service ctcss processor 21 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.1.4 timing diagrams for the following conditions unless otherwise specified: xtal frequency = 4.0mhz, v dd = 3.0v to 5.0v, t amb = -40c to 85c. parameter notes min. typ. max. units t cse "cs-enable to clock-high" 2.0 s t csh last "clock-high to cs-high" 4.0 s t hiz "cs-high to reply output 3-state" 2.0 s t csoff "cs-high" time between transactions 2.0 s t nxt "inter-byte" time 4.0 s t ck "clock-cycle" time 2.0 s notes: 1. depending on the command, 1 or 2 bytes of command data are transmitted to the peripheral msb (bit 7) first, lsb (bit 0) last. reply data is read from the peripheral msb (bit 7) first, lsb (bit 0) last. 2. data is clocked into and out of the peripheral on the rising serial clock edge. 3. loaded commands are acted upon at the end of each command. 4. to allow for differing c serial interface formats "c-bus" compatible ics are able to work with either polarity serial clock pulses. 7 6 5 4 3 21 0 7 6 5 4 3 21 0 7 6 5 4 3 21 0 0 1 2 3 4 5 6 7 7 6 5 4 3 21 0 msb lsb first reply data byte last reply data byte logic level is not important reply data msb lsb address/command byte command data serial clock t cse first data byte last data byte t hiz t ck t nxt t nxt t csh t csoff cs figure 6: "c-bus" timing
family radio service ctcss processor 22 cmx808a preliminary information ? 1999 mx-com, inc. www. mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20480199.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective compa nies. 6.2 packaging figure 7: 20-pin tssop mechanical outline: order as part no. cmx808ae3 note : all dimensions in inches (mm.) angles are in degrees package tolerances a b c e e1 h typ. max. min. dim. j j1 p y t k l 0.220 (5.59) 0.555 (14.04) 0.670 (17.02) 7 0.160 (4.05) 1.270 (32.26) 0.151 (3.84) 0.100 (2.54) 0.121 (3.07) 0.600 (15.24) 0.590 (14.99) 0.625 (15.88) 0.015 (0.38) 0.045 (1.14) 0.008 (0.20) 0.015 (0.38) 0.015 (0.38) 0.023 (0.58) 0.040 (1.02) 0.065 (1.65) 0.066 (1.67) 0.074 (1.88) 1.200 (30.48) 0.500 (12.70) h k l j1 j1 j j p p c c b b a a pin1 pin1 t t e e e1 e1 y figure 8: 24-pin pdip mechanical outline: order as part no. CMX808AP4

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