diff --git a/I2CManager.h b/I2CManager.h index 7df0803..f966d77 100644 --- a/I2CManager.h +++ b/I2CManager.h @@ -111,6 +111,11 @@ * */ +// Maximum number of retries on an I2C operation +// A value of zero will disable retries. +// Maximum value is 254 (unsigned byte counter) +#define MAX_I2C_RETRIES 2 + // Add following line to config.h to enable Wire library instead of native I2C drivers //#define I2C_USE_WIRE @@ -265,6 +270,7 @@ private: static volatile unsigned long startTime; static unsigned long timeout; // Transaction timeout in microseconds. 0=disabled. + static uint8_t retryCounter; // Count of retries void startTransaction(); diff --git a/I2CManager_NonBlocking.h b/I2CManager_NonBlocking.h index fbcb98a..2793823 100644 --- a/I2CManager_NonBlocking.h +++ b/I2CManager_NonBlocking.h @@ -223,16 +223,15 @@ void I2CManagerClass::handleInterrupt() { // Update hardware state machine I2C_handleInterrupt(); - // Enable interrupts to minimise effect on other interrupt code - interrupts(); - // Check if current request has completed. If there's a current request // and state isn't active then state contains the completion status of the request. if (state != I2C_STATE_ACTIVE && currentRequest != NULL) { - // Remove completed request from head of queue - ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { + // Operation has completed. + if (state == I2C_STATUS_OK || ++retryCounter > MAX_I2C_RETRIES) { + // Status is OK, or has failed and retry count exceeded. + // Remove completed request from head of queue I2CRB * t = queueHead; - if (t == queueHead) { + if (t == currentRequest) { queueHead = t->nextRequest; if (!queueHead) queueTail = queueHead; t->nBytes = rxCount; @@ -241,12 +240,21 @@ void I2CManagerClass::handleInterrupt() { // I2C state machine is now free for next request currentRequest = NULL; state = I2C_STATE_FREE; - - // Start next request (if any) - I2CManager.startTransaction(); } + retryCounter = 0; + } else { + // Status is failed and retry permitted. + // Retry previous request. + state = I2C_STATE_FREE; } } + + if (state == I2C_STATE_FREE && queueHead != NULL) { + // Allow any pending interrupts before starting the next request. + interrupts(); + // Start next request + I2CManager.startTransaction(); + } } // Fields in I2CManager class specific to Non-blocking implementation. @@ -261,5 +269,6 @@ volatile uint8_t I2CManagerClass::bytesToSend; volatile uint8_t I2CManagerClass::bytesToReceive; volatile unsigned long I2CManagerClass::startTime; unsigned long I2CManagerClass::timeout = 0; +uint8_t I2CManagerClass::retryCounter = 0; #endif \ No newline at end of file diff --git a/I2CManager_Wire.h b/I2CManager_Wire.h index 87152e7..aa0189f 100644 --- a/I2CManager_Wire.h +++ b/I2CManager_Wire.h @@ -49,9 +49,14 @@ void I2CManagerClass::_setClock(unsigned long i2cClockSpeed) { * Initiate a write to an I2C device (blocking operation on Wire) ***************************************************************************/ uint8_t I2CManagerClass::write(uint8_t address, const uint8_t buffer[], uint8_t size, I2CRB *rb) { - Wire.beginTransmission(address); - if (size > 0) Wire.write(buffer, size); - rb->status = Wire.endTransmission(); + uint8_t status = I2C_STATUS_OK; + uint8_t retryCount = 0; + do { + Wire.beginTransmission(address); + if (size > 0) Wire.write(buffer, size); + status = Wire.endTransmission(); + } while (!(status == I2C_STATUS_OK || ++retryCount > MAX_I2C_RETRIES)); + rb->status = status; return I2C_STATUS_OK; } @@ -75,17 +80,21 @@ uint8_t I2CManagerClass::read(uint8_t address, uint8_t readBuffer[], uint8_t rea { uint8_t status = I2C_STATUS_OK; uint8_t nBytes = 0; - if (writeSize > 0) { - Wire.beginTransmission(address); - Wire.write(writeBuffer, writeSize); - status = Wire.endTransmission(false); // Don't free bus yet - } - if (status == I2C_STATUS_OK) { - Wire.requestFrom(address, (size_t)readSize); - while (Wire.available() && nBytes < readSize) - readBuffer[nBytes++] = Wire.read(); - if (nBytes < readSize) status = I2C_STATUS_TRUNCATED; - } + uint8_t retryCount = 0; + do { + if (writeSize > 0) { + Wire.beginTransmission(address); + Wire.write(writeBuffer, writeSize); + status = Wire.endTransmission(false); // Don't free bus yet + } + if (status == I2C_STATUS_OK) { + Wire.requestFrom(address, (size_t)readSize); + while (Wire.available() && nBytes < readSize) + readBuffer[nBytes++] = Wire.read(); + if (nBytes < readSize) status = I2C_STATUS_TRUNCATED; + } + } while (!(status == I2C_STATUS_OK || ++retryCount > MAX_I2C_RETRIES)); + rb->nBytes = nBytes; rb->status = status; return I2C_STATUS_OK;