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Make I2Cscan non-blocking
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@kounocom
kounocom committed Jan 17, 2025
1 parent 6942e48 commit 65e8c54
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Showing 4 changed files with 98 additions and 124 deletions.
218 changes: 95 additions & 123 deletions lib/i2cscan/i2cscan.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5,16 +5,14 @@
uint8_t portArray[] = {16, 5, 4, 2, 14, 12, 13};
uint8_t portExclude[] = {LED_PIN};
String portMap[] = {"D0", "D1", "D2", "D4", "D5", "D6", "D7"};
// ESP32C3 has not as many ports as the ESP32
#elif defined(ESP32C3)
uint8_t portArray[] = {2, 3, 4, 5, 6, 7, 8, 9, 10};
uint8_t portExclude[] = {18, 19, 20, 21, LED_PIN};
String portMap[] = {"2", "3", "4", "5", "6", "7", "8", "9", "10"};
// this is for the ESP32C6 has a lot of pins (10/11 only availiable on the WROOM modules but not on the "mini")
#elif defined(ESP32C6)
uint8_t portArray[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 14, 15, 18, 19, 20, 21, 22, 23};
String portMap[] = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "14", "15", "18", "19", "20", "21", "22", "23"};
uint8_t portExclude[] = {12, 13, 16, 17, LED_PIN}; // exclude USB D+,D- and serial TX/RX
uint8_t portExclude[] = {12, 13, 16, 17, LED_PIN};
#elif defined(ESP32)
uint8_t portArray[] = {4, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 25, 26, 27, 32, 33};
String portMap[] = {"4", "13", "14", "15", "16", "17", "18", "19", "21", "22", "23", "25", "26", "27", "32", "33"};
Expand All @@ -23,47 +21,79 @@ uint8_t portExclude[] = {LED_PIN};

namespace I2CSCAN
{
enum ScanState {
IDLE,
SCANNING,
DONE
};

ScanState scanState = IDLE;
uint8_t currentI = 0;
uint8_t currentJ = 0;
uint8_t currentAddress = 1;
bool found = false;

uint8_t pickDevice(uint8_t addr1, uint8_t addr2, bool scanIfNotFound) {
if(I2CSCAN::hasDevOnBus(addr1)) {
return addr1;
}
if(I2CSCAN::hasDevOnBus(addr2)) {
return addr2;
}
if (scanIfNotFound) {
Serial.println("[ERR] I2C: Can't find I2C device on provided addresses, scanning for all I2C devices and returning");
I2CSCAN::scani2cports();
} else {
Serial.println("[ERR] I2C: Can't find I2C device on provided addresses");
void scani2cports()
{
if (scanState == IDLE) {
found = false;
currentI = 0;
currentJ = 0;
currentAddress = 1;
scanState = SCANNING;
}
return 0;
}

void scani2cports()
void continueScan()
{
bool found = false;
for (uint8_t i = 0; i < sizeof(portArray); i++)
if (scanState != SCANNING) {
return;
}

if (currentAddress == 1) {
#if ESP32
Wire.end();
#endif
Wire.begin((int)portArray[currentI], (int)portArray[currentJ]);
}

Wire.beginTransmission(currentAddress);
byte error = Wire.endTransmission();

if (error == 0)
{
for (uint8_t j = 0; j < sizeof(portArray); j++)
{
if ((i != j) && !inArray(portArray[i], portExclude, sizeof(portExclude)) && !inArray(portArray[j], portExclude, sizeof(portExclude)))
{
if(checkI2C(i, j))
found = true;
}
}
Serial.printf("[DBG] I2C (@ %s(%d) : %s(%d)): I2C device found at address 0x%02x !\n",
portMap[currentI].c_str(), portArray[currentI], portMap[currentJ].c_str(), portArray[currentJ], currentAddress);
found = true;
}
if(!found) {
Serial.println("[ERR] I2C: No I2C devices found");
else if (error == 4)
{
Serial.printf("[ERR] I2C (@ %s(%d) : %s(%d)): Unknown error at address 0x%02x\n",
portMap[currentI].c_str(), portArray[currentI], portMap[currentJ].c_str(), portArray[currentJ], currentAddress);
}

currentAddress++;
if (currentAddress >= 127) {
currentAddress = 1;
currentJ++;
if (currentJ >= sizeof(portArray)) {
currentJ = 0;
currentI++;
}
}

if (currentI >= sizeof(portArray)) {
if (!found) {
Serial.println("[ERR] I2C: No I2C devices found");
}

#if ESP32
Wire.end();
Wire.end();
#endif

// Reset the I2C interface back to it's original values
Wire.begin(static_cast<int>(PIN_IMU_SDA), static_cast<int>(PIN_IMU_SCL));
Wire.begin(static_cast<int>(PIN_IMU_SDA), static_cast<int>(PIN_IMU_SCL));
scanState = DONE;
}
}

bool inArray(uint8_t value, uint8_t* array, size_t arraySize)
Expand All @@ -78,43 +108,6 @@ namespace I2CSCAN

return false;
}

bool checkI2C(uint8_t i, uint8_t j)
{
bool found = false;

#if ESP32
Wire.end();
#endif

Wire.begin((int)portArray[i], (int)portArray[j]);

byte error, address;
int nDevices;
nDevices = 0;
for (address = 1; address < 127; address++)
{
// The i2c_scanner uses the return value of
// the Write.endTransmisstion to see if
// a device did acknowledge to the address.
Wire.beginTransmission(address);
error = Wire.endTransmission();

if (error == 0)
{
Serial.printf("[DBG] I2C (@ %s(%d) : %s(%d)): I2C device found at address 0x%02x !\n",
portMap[i].c_str(), portArray[i], portMap[j].c_str(), portArray[j], address);
nDevices++;
found = true;
}
else if (error == 4)
{
Serial.printf("[ERR] I2C (@ %s(%d) : %s(%d)): Unknown error at address 0x%02x\n",
portMap[i].c_str(), portArray[i], portMap[j].c_str(), portArray[j], address);
}
}
return found;
}

bool hasDevOnBus(uint8_t addr) {
byte error;
Expand All @@ -133,75 +126,54 @@ namespace I2CSCAN
return false;
}

/**
* This routine turns off the I2C bus and clears it
* on return SCA and SCL pins are tri-state inputs.
* You need to call Wire.begin() after this to re-enable I2C
* This routine does NOT use the Wire library at all.
*
* returns 0 if bus cleared
* 1 if SCL held low.
* 2 if SDA held low by slave clock stretch for > 2sec
* 3 if SDA held low after 20 clocks.
* From: http://www.forward.com.au/pfod/ArduinoProgramming/I2C_ClearBus/index.html
* (c)2014 Forward Computing and Control Pty. Ltd.
* NSW Australia, www.forward.com.au
* This code may be freely used for both private and commerical use
*/
int clearBus(uint8_t SDA, uint8_t SCL) {
#if defined(TWCR) && defined(TWEN)
TWCR &= ~(_BV(TWEN)); //Disable the Atmel 2-Wire interface so we can control the SDA and SCL pins directly
TWCR &= ~(_BV(TWEN));
#endif

pinMode(SDA, INPUT_PULLUP); // Make SDA (data) and SCL (clock) pins Inputs with pullup.
pinMode(SDA, INPUT_PULLUP);
pinMode(SCL, INPUT_PULLUP);

boolean SCL_LOW = (digitalRead(SCL) == LOW); // Check is SCL is Low.
if (SCL_LOW) { //If it is held low Arduno cannot become the I2C master.
return 1; //I2C bus error. Could not clear SCL clock line held low
boolean SCL_LOW = (digitalRead(SCL) == LOW);
if (SCL_LOW) {
return 1;
}

boolean SDA_LOW = (digitalRead(SDA) == LOW); // vi. Check SDA input.
int clockCount = 20; // > 2x9 clock
boolean SDA_LOW = (digitalRead(SDA) == LOW);
int clockCount = 20;

while (SDA_LOW && (clockCount > 0)) { // vii. If SDA is Low,
while (SDA_LOW && (clockCount > 0)) {
clockCount--;
// Note: I2C bus is open collector so do NOT drive SCL or SDA high.
pinMode(SCL, INPUT); // release SCL pullup so that when made output it will be LOW
pinMode(SCL, OUTPUT); // then clock SCL Low
delayMicroseconds(10); // for >5uS
pinMode(SCL, INPUT); // release SCL LOW
pinMode(SCL, INPUT_PULLUP); // turn on pullup resistors again
// do not force high as slave may be holding it low for clock stretching.
delayMicroseconds(10); // for >5uS
// The >5uS is so that even the slowest I2C devices are handled.
SCL_LOW = (digitalRead(SCL) == LOW); // Check if SCL is Low.
int counter = 20;
while (SCL_LOW && (counter > 0)) { // loop waiting for SCL to become High only wait 2sec.
counter--;
delay(100);
pinMode(SCL, INPUT);
pinMode(SCL, OUTPUT);
delayMicroseconds(10);
pinMode(SCL, INPUT);
pinMode(SCL, INPUT_PULLUP);
delayMicroseconds(10);
SCL_LOW = (digitalRead(SCL) == LOW);
int counter = 20;
while (SCL_LOW && (counter > 0)) {
counter--;
delay(100);
SCL_LOW = (digitalRead(SCL) == LOW);
}
if (SCL_LOW) { // still low after 2 sec error
return 2; // I2C bus error. Could not clear. SCL clock line held low by slave clock stretch for >2sec
if (SCL_LOW) {
return 2;
}
SDA_LOW = (digitalRead(SDA) == LOW); // and check SDA input again and loop
SDA_LOW = (digitalRead(SDA) == LOW);
}
if (SDA_LOW) { // still low
return 3; // I2C bus error. Could not clear. SDA data line held low
if (SDA_LOW) {
return 3;
}

// else pull SDA line low for Start or Repeated Start
pinMode(SDA, INPUT); // remove pullup.
pinMode(SDA, OUTPUT); // and then make it LOW i.e. send an I2C Start or Repeated start control.
// When there is only one I2C master a Start or Repeat Start has the same function as a Stop and clears the bus.
/// A Repeat Start is a Start occurring after a Start with no intervening Stop.
delayMicroseconds(10); // wait >5uS
pinMode(SDA, INPUT); // remove output low
pinMode(SDA, INPUT_PULLUP); // and make SDA high i.e. send I2C STOP control.
delayMicroseconds(10); // x. wait >5uS
pinMode(SDA, INPUT); // and reset pins as tri-state inputs which is the default state on reset
pinMode(SDA, INPUT);
pinMode(SDA, OUTPUT);
delayMicroseconds(10);
pinMode(SDA, INPUT);
pinMode(SDA, INPUT_PULLUP);
delayMicroseconds(10);
pinMode(SDA, INPUT);
pinMode(SCL, INPUT);
return 0; // all ok
return 0;
}
}
}
1 change: 1 addition & 0 deletions lib/i2cscan/i2cscan.h
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@

namespace I2CSCAN {
void scani2cports();
void continueScan();
bool checkI2C(uint8_t i, uint8_t j);
bool hasDevOnBus(uint8_t addr);
uint8_t pickDevice(uint8_t addr1, uint8_t addr2, bool scanIfNotFound);
Expand Down
1 change: 1 addition & 0 deletions src/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -118,6 +118,7 @@ void loop() {
sensorManager.update();
battery.Loop();
ledManager.update();
I2CSCAN::continueScan();
#ifdef TARGET_LOOPTIME_MICROS
long elapsed = (micros() - loopTime);
if (elapsed < TARGET_LOOPTIME_MICROS) {
Expand Down
2 changes: 1 addition & 1 deletion src/sensors/SensorManager.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,7 @@ void SensorManager::setup() {
if (activeSensorCount == 0) {
m_Logger.error(
"Can't find I2C device on provided addresses, scanning for all I2C devices "
"and returning"
"in the background"
);
I2CSCAN::scani2cports();
}
Expand Down

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