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Improve I2C bus recovery of Interrupted READ cycle #1767

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Aug 18, 2018
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Improve I2C bus recovery of Interrupted READ cycle #1767

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23 changes: 11 additions & 12 deletions cores/esp32/esp32-hal-i2c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1350,33 +1350,32 @@ static void i2cReleaseISR(i2c_t * i2c)
}

static bool i2cCheckLineState(int8_t sda, int8_t scl){
if(sda < 0 || scl < 0){
return true;//return true since there is nothing to do
if(sda < 0 || scl < 0){
return false;//return false since there is nothing to do
}
// if the bus is not 'clear' try the recommended recovery sequence, START, 9 Clocks, STOP
// if the bus is not 'clear' try the cycling SCL until SDA goes High or 9 cycles
digitalWrite(sda, HIGH);
digitalWrite(scl, HIGH);
pinMode(sda, PULLUP|OPEN_DRAIN|OUTPUT|INPUT);
pinMode(scl, PULLUP|OPEN_DRAIN|OUTPUT|INPUT);
pinMode(sda, PULLUP|OPEN_DRAIN|INPUT);
pinMode(scl, PULLUP|OPEN_DRAIN|OUTPUT);

if(!digitalRead(sda) || !digitalRead(scl)) { // bus in busy state
log_w("invalid state sda=%d, scl=%d\n", digitalRead(sda), digitalRead(scl));
digitalWrite(sda, HIGH);
log_w("invalid state sda(%d)=%d, scl(%d)=%d", sda, digitalRead(sda), scl, digitalRead(scl));
digitalWrite(scl, HIGH);
delayMicroseconds(5);
digitalWrite(sda, LOW);
for(uint8_t a=0; a<9; a++) {
delayMicroseconds(5);
digitalWrite(scl, LOW);
delayMicroseconds(5);
digitalWrite(scl, HIGH);
if(digitalRead(sda)){ // bus recovered
log_d("Recovered after %d Cycles",a+1);
break;
}
}
delayMicroseconds(5);
digitalWrite(sda, HIGH);
}

if(!digitalRead(sda) || !digitalRead(scl)) { // bus in busy state
log_e("Bus Invalid State, TwoWire() Can't init");
log_e("Bus Invalid State, TwoWire() Can't init sda=%d, scl=%d",digitalRead(sda),digitalRead(scl));
return false; // bus is busy
}
return true;
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