8000 Preserve Custom SDA,SCL and Frequency when calling Wire.begin() · stickbreaker/arduino-esp32@da6be57 · GitHub
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Preserve Custom SDA,SCL and Frequency when calling Wire.begin()
This change will not reset the SCL, SDA and Frequency values to their default value if `Wire.begin()` is call without any parameters. Arduino libraries that use `Wire()` usually have a call to `Wire.begin()` inside their initialization call. Without this change, any custom pin assignments are lost whenever `Wire.begin()` is called.
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-17
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+34
-17
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‎libraries/Wire/src/Wire.cpp

Lines changed: 34 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -62,25 +62,37 @@ if(i2c){
6262

6363
void TwoWire::begin(int sdaPin, int sclPin, uint32_t frequency)
6464
{
65-
if(sdaPin < 0) {
66-
if(num == 0) {
67-
sdaPin = SDA;
68-
} else {
69-
return;
70-
}
65+
if(sdaPin < 0) { // default param passed
66+
if(num == 0) {
67+
if(sda==-1) sdaPin = SDA; //use Default Pin
68+
else sdaPin = sda; // reuse prior pin
69+
}
70+
else {
71+
if(sda==-1) {
72+
log_e("no Default SDA Pin for Second Peripheral");
73+
return; //no Default pin for Second Peripheral
74+
}
75+
else sdaPin = sda; // reuse prior pin
76+
}
7177
}
7278

73-
if(sclPin < 0) {
74-
if(num == 0) {
75-
sclPin = SCL;
76-
} else {
77-
return;
79+
if(sclPin < 0) { // default param passed
80+
if(num == 0) {
81+
if(scl==-1) sclPin = SCL; // use Default pin
82+
else sclPin = scl; // reuse prior pin
83+
}
84+
else {
85+
if(scl==-1){
86+
log_e("no Default SCL Pin for Second Peripheral");
87+
return; //no Default pin for Second Peripheral
7888
}
89+
else sclPin = scl; // reuse prior pin
90+
}
7991
}
80-
81-
if(!initHardware(sdaPin, sclPin, frequency)) return;
8292

83-
flush();
93+
if(!initHardware(sdaPin, sclPin, frequency)) return;
94+
95+
flush();
8496

8597
}
8698

@@ -97,8 +109,6 @@ void TwoWire::setClock(uint32_t frequency)
97109
i2cSetFrequency(i2c, frequency);
98110
}
99111

100-
/*@StickBreaker common handler for processing the queued commands
101-
*/
102112
bool TwoWire::initHardware(int sdaPin, int sclPin, uint32_t frequency){
103113

104114
i2cDetachSCL(i2c,scl); // detach pins before resetting I2C perpherial
@@ -107,7 +117,12 @@ bool TwoWire::initHardware(int sdaPin, int sclPin, uint32_t frequency){
107117
if(i2c == NULL) {
108118
return false;
109119
}
110-
120+
121+
if(frequency==0) {// don't change existing frequency
122+
frequency = i2cGetFrequency(i2c);
123+
}
124+
if(frequency==0) frequency = 100000L; // default to 100khz
125+
111126
i2cSetFrequency(i2c, frequency);
112127

113128
sda = sdaPin;
@@ -148,6 +163,8 @@ bool TwoWire::initHardware(int sdaPin, int sclPin, uint32_t frequency){
148163
return true;
149164
}
150165

166+
/*@StickBreaker common handler for processing the queued commands
167+
*/
151168
i2c_err_t TwoWire::processQueue(uint32_t * readCount){
152169
last_error=i2cProcQueue(i2c,readCount,_timeOutMillis);
153170
if(last_error==I2C_ERROR_BUSY){ // try to clear the bus

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