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Hold transmitter in reset during rate change (#7248)

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geoffday67 2020-04-27 18:58:47 +01:00 committed by GitHub
parent 1bb5ccf71e
commit ec7644227e
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1 changed files with 16 additions and 2 deletions
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18
cores/esp8266/core_esp8266_i2s.cpp
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@ -464,14 +464,28 @@ void i2s_set_dividers(uint8_t div1, uint8_t div2) {
div1 &= I2SBDM;
div2 &= I2SCDM;
/*
Following this post: https://github.com/esp8266/Arduino/issues/2590
We should reset the transmitter while changing the configuration bits to avoid random distortion.
*/
uint32_t i2sc_temp = I2SC;
i2sc_temp |= (I2STXR); // Hold transmitter in reset
I2SC = i2sc_temp;
// trans master(active low), recv master(active_low), !bits mod(==16 bits/chanel), clear clock dividers
I2SC &= ~(I2STSM | I2SRSM | (I2SBMM << I2SBM) | (I2SBDM << I2SBD) | (I2SCDM << I2SCD));
i2sc_temp &= ~(I2STSM | I2SRSM | (I2SBMM << I2SBM) | (I2SBDM << I2SBD) | (I2SCDM << I2SCD));
// I2SRF = Send/recv right channel first (? may be swapped form I2S spec of WS=0 => left)
// I2SMR = MSB recv/xmit first
// I2SRMS, I2STMS = 1-bit delay from WS to MSB (I2S format)
// div1, div2 = Set I2S WS clock frequency. BCLK seems to be generated from 32x this
I2SC |= I2SRF | I2SMR | I2SRMS | I2STMS | (div1 << I2SBD) | (div2 << I2SCD);
i2sc_temp |= I2SRF | I2SMR | I2SRMS | I2STMS | (div1 << I2SBD) | (div2 << I2SCD);
I2SC = i2sc_temp;
i2sc_temp &= ~(I2STXR); // Release reset
I2SC = i2sc_temp;
}
float i2s_get_real_rate(){