CMX838D1 View Datasheet(PDF) - CML Microsystems Plc
Part Name
Description
MFG CO.
'CMX838D1' PDF : 71 Pages View PDF
FRS/PMR446/GMRS Family Radio Processor
CMX838
8 BIT SUBAUDIO TASK DATA ($95): 10110010b = $B2
• Load hex value resulting from $80 logically ordered with $32 (‘254.1Hz tone select’)
{10000000b | 00110010b} = 10110010b = $B2
• When in Rx mode and MSB of $95 is “1”, the desired tone(s) is (are) loaded onto the ‘tone watch list’
• When in Rx mode and MSB of $95 is “0”, the desired tone(s) is (are) removed from the ‘tone watch
list’
TONE SIGNALING CONTROL ($93): 01010100b = $54
• Enable power for subaudio section (01)
• IRQ when detect status change (01)
• Load ‘enable/disable tone detector’ task (0100)
IF DESIRED, REPEAT TONE LOADING AND TONE DETECTOR ENABLING STEPS (immediately prior
two steps) TO BUILD A ‘TONE WATCH LIST.’
TONE SIGNALING CONTROL ($93): 01010000b = $50
• Enable power for subaudio section (01)
• IRQ when detect status change (01)
• Load ‘normal operation’ task (0000)
SUBAUDIO ANALOG CONTROL ($97): 00010000 00010000b = $1010
• Rx Input passed to subaudio filter input (0)
• Subaudio LPF gain set to +20dB (default for Rx mode) (0)
• Subaudio LPF configured as 65Hz high pass DC blocking filter (0)
• Tx subaudio level set to 0.0dB (10000)
• Tx subaudio filter gain counter set to 0 for normal operation (0)
• Subaudio filter configuration set to 0 for normal operation (0)
• DC restoration set to 0 for normal operation (0)
• Rx subaudio level set to 0.0dB (10000)
6.6.4 RX, multiple subaudio tone detect - Tone Cloning™
This RX scenario configures the CMX838 for:
• Baseband clock generation from RF synthesizer clock
• Rx Enabled
• Input from Rx In pin
• Signal passed through LPF, HPF, and de-emphasis in audio path (limiter bypassed)
• CTCSS decoder enabled, all TIA-603 standard tones selected for detection (recognition)
Tone Cloning™ is a function that allows one FRS radio to quickly identify and clone the CTCSS tone setting
transmitted by another radio. For end users, Tone Cloning™ simplifies the setup and operation of FRS radios
the CTCSS tone programming process on the radio’s user interface.
After the CMX838’s TIA-603 standard tone set tone decoders are activated in a tone ‘watch list’, the CMX838
then will promiscuously listen for any of those tones and identify it when it is received. The identity can then
be used to efficiently set up the CMX838 CTCSS encoder to continue to use that tone.
6.6.4.1 Register Descriptions:
GENERAL RESET ($01): (if required)
SYNTHESIZER BASEBAND CLOCK CONTROL ($89): 10010000b = $90
• baseband and synthesizer reference clock from REF IN, xtal amp disabled (10)
• REF IN frequency 12.8MHz (0100)
• Bits 1-0 are don’t cares as xtal is not used
SETUP ($80): 00111110b = $3E
• Rx Enabled (0)
• Audio input signal supplied from RX Input (01)
• Audio signal passed through HPF out to limiter (1111)
• Bit 0 is unused (0)
2003 CML Microsystems Plc
62
D/838/8
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