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Linearize TX15 audio volume control #6555

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Linearize TX15 audio volume control #6555

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32f7e1e
Linearize TX15 audio volume
mha1 Aug 27, 2025
e4be5ae
moved lookup table to TX15 specific audio_driver to keep TAS2506 driv…
mha1 Aug 28, 2025
78f4d81
cleanup
mha1 Aug 28, 2025
00a8b9f
Merge branch 'main' into TX15-volume-adjust
mha1 Nov 21, 2025
d4296de
Merge branch 'main' into TX15-volume-adjust
mha1 Dec 6, 2025
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18 changes: 17 additions & 1 deletion radio/src/boards/rm-h750/audio_driver.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,17 @@ static void audio_update_dma_buffer(uint8_t tc)
}
}

// TX15 HP cannot handle the full power of TAS2505
// max volume is limited to 15db attenuation
// Index 0 = silence
// 1 = low volume
// 11 = center
// 23 = max volume
static const uint8_t volumeScale[VOLUME_LEVEL_MAX + 1] =
{
0, 114, 90, 75, 63, 55, 49, 45, 42, 39, 37, 35, 33, 31, 29, 27, 25, 23, 21, 19, 18, 17, 16, 15
};

bool audioHeadphoneDetect()
{
#if defined(KCX_BTAUDIO)
Expand All @@ -171,12 +182,17 @@ bool audioHeadphoneDetect()

void audioSetVolume(uint8_t volume)
{
if (volume > VOLUME_LEVEL_MAX) {
volume = VOLUME_LEVEL_MAX;
}

#if defined(KCX_BTAUDIO)
// KCX need a volume boost
if (btAudioLinked())
volume = volume + (volume >> 2);
#endif
tas2505_set_volume(&_tas2505, volume * 9 / 10, audioHeadphoneDetect()); // TX15 HP cannot handle the full power of TAS2505

tas2505_set_volume(&_tas2505, volumeScale[volume], audioHeadphoneDetect());
}

extern "C" void DMA1_Stream4_IRQHandler(void)
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25 changes: 7 additions & 18 deletions radio/src/drivers/tas2505.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -128,29 +128,18 @@ int tas2505_init(tas2505_t* dev)
return 0;
}

// adjust this value for a volume level just above the silence
// values is attenuation in dB, higher value - less volume
// max value is 126
#define VOLUME_MIN_DB 60

void tas2505_set_volume(tas2505_t* dev, uint8_t volume, bool headphone_mode = false)
{
if (volume > VOLUME_LEVEL_MAX) {
volume = VOLUME_LEVEL_MAX;
}
// maximum volume is 0x00 and total silence is 0xFE
if (volume == 0) {
volume = 0xFE;
}

if (headphone_mode) {
tas2505_write_reg(dev, TAS2505_SPKVOL1, 0xFE);
tas2505_write_reg(dev, TAS2505_HP_VOL, 0xFE);
tas2505_write_reg(dev, TAS2505_HP_VOL, volume);
} else {
uint32_t vol = (VOLUME_MIN_DB * 2) -
((uint32_t)volume * (VOLUME_MIN_DB * 2)) / VOLUME_LEVEL_MAX;
if (headphone_mode) {
tas2505_write_reg(dev, TAS2505_SPKVOL1, 0xFE);
tas2505_write_reg(dev, TAS2505_HP_VOL, vol);
} else {
tas2505_write_reg(dev, TAS2505_SPKVOL1, vol);
tas2505_write_reg(dev, TAS2505_HP_VOL, 0xFE);
}
tas2505_write_reg(dev, TAS2505_SPKVOL1, volume);
tas2505_write_reg(dev, TAS2505_HP_VOL, 0xFE);
}
}