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base repository: OpenRTX/openrtx.github.io
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head repository: turbo2ltr/openrtx.github.io
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Commits on Aug 28, 2022

  1. Update md380.md

    @turbo2ltr
    turbo2ltr authored Aug 28, 2022
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@@ -46,3 +46,14 @@ TIM7 is configured with a prescale value of 7 and a reload value of 0x3e7 (999 d


## Memory mapping

## Output Audio Paths
### Unmodded Radio
The decoded DMR audio output from the HS_C5000 LINE_OUT (Pin 10) passes through op amp U203 and is routed as the input of the volume knob (VOL_OUT on the schematic). The volume pot controls the signal level sent to Input 1 (Pin 7) of the audio amp U204.
In FM mode, the demod audio output (AF_OUT) is passed through U102 op amps before routed to the volume knob input (VOL_OUT), so it too is controlled by the volume pot.

PWM out from STM PC8 (Pin 65) is used to provide beeps and startup tones to the speaker that are not controlled by the volume knob. The output signal from this pin passes through a series of resistors and a cap R339,R340, C337, R341. The schematic indicates that this signal is sent to the volume pot (VOL_OUT) but this is not correct. It is connected directly to pin 7 of U204 (input 1 of audio amp) completely bypassing the volume knob and where it is mixed with the signals connected to VOL_OUT and were passed though the volume pot.

### OpenRTX Modded Radio
PWM out from STM PC8 (Pin 65) is used in OpenRTX to output the decoded M17 audio to the speaker during RX, as well as generate M17 encoded audio sent to the modulator during TX (2T/5T/DTMF_OUT). During TX, the M17 encoded audio on 2T/5T/DTMF_OUT is sent into the HR_C5000 Pin 5 which then generates the MOD1 and MOD2 signals out of pin 74 and 75 and into the VCO.
The audio path in FM mode remains unchanged.