Fix I2S timing (#728)

earlephilhower · web-flow · commit 5ab19e9a9f4d · 2022-07-29T12:40:04.000-07:00
BCLK was running at 50% of expected speed. Fixes #714
diff --git a/libraries/I2S/src/I2S.cpp b/libraries/I2S/src/I2S.cpp
@@ -78,7 +78,7 @@ bool I2S::setBuffers(size_t buffers, size_t bufferWords, int32_t silenceSample)
 bool I2S::setFrequency(int newFreq) {
     _freq = newFreq;
     if (_running) {
-        float bitClk = _freq * _bps * 2.0;
+        float bitClk = _freq * _bps * 2.0 /* channels */ * 2.0 /* edges per clock */;
         pio_sm_set_clkdiv(_pio, _sm, (float)clock_get_hz(clk_sys) / bitClk);
     }
     return true;

Original file line number	Diff line number	Diff line change
`@@ -78,7 +78,7 @@ bool I2S::setBuffers(size_t buffers, size_t bufferWords, int32_t silenceSample)`
`78`	`78`	`bool I2S::setFrequency(int newFreq) {`
`79`	`79`	`_freq = newFreq;`
`80`	`80`	`if (_running) {`
`81`		`- float bitClk = _freq * _bps * 2.0;`
	`81`	`+ float bitClk = _freq * _bps * 2.0 /* channels / 2.0 /* edges per clock */;`
`82`	`82`	`pio_sm_set_clkdiv(_pio, _sm, (float)clock_get_hz(clk_sys) / bitClk);`
`83`	`83`	`}`
`84`	`84`	`return true;`