diff --git a/radio/src/targets/common/arm/stm32/audio_dac_driver.cpp b/radio/src/targets/common/arm/stm32/audio_dac_driver.cpp index f25933cb0ce..571807dbac3 100644 --- a/radio/src/targets/common/arm/stm32/audio_dac_driver.cpp +++ b/radio/src/targets/common/arm/stm32/audio_dac_driver.cpp @@ -170,12 +170,24 @@ static void dac_close_dma_xfer() { LL_DMA_DisableIT_TC(AUDIO_DMA, AUDIO_DMA_Stream); LL_DMA_DisableIT_HT(AUDIO_DMA, AUDIO_DMA_Stream); - // TODO: reset flags LL_DMA_DisableStream(AUDIO_DMA, AUDIO_DMA_Stream); + + // clear pending flags so they don't carry over to the next transfer + stm32_dma_check_tc_flag(AUDIO_DMA, AUDIO_DMA_Stream); + stm32_dma_check_ht_flag(AUDIO_DMA, AUDIO_DMA_Stream); } static void dac_start_dma() { + // re-arm from the start of the buffer: a mid-transfer stop leaves NDTR and the + // memory address partway, which desyncs the HT/TC half tracking + LL_DMA_DisableStream(AUDIO_DMA, AUDIO_DMA_Stream); + LL_DMA_SetMemoryAddress(AUDIO_DMA, AUDIO_DMA_Stream, (uintptr_t)_dma_buffer); + LL_DMA_SetDataLength(AUDIO_DMA, AUDIO_DMA_Stream, DMA_BUFFER_LEN); + + stm32_dma_check_tc_flag(AUDIO_DMA, AUDIO_DMA_Stream); + stm32_dma_check_ht_flag(AUDIO_DMA, AUDIO_DMA_Stream); + // enable DMA stream and transfer complete interrupt LL_DMA_EnableIT_HT(AUDIO_DMA, AUDIO_DMA_Stream); LL_DMA_EnableIT_TC(AUDIO_DMA, AUDIO_DMA_Stream); @@ -192,6 +204,10 @@ void audioConsumeCurrentBuffer() { if (!LL_DMA_IsEnabledStream(AUDIO_DMA, AUDIO_DMA_Stream)) { if (!audio_update_dma_buffer(0)) { + // prime the second half as well so the first full DMA cycle plays valid + // data and the half tracking starts aligned (ignore the result: if no + // more data is available it is filled with silence) + audio_update_dma_buffer(1); #if defined(AUDIO_MUTE_GPIO) audioUnmute(); #endif