/**
* Request data from a SLAVE as a MASTER
*/
uint8_t DWire::requestFrom(uint_fast8_t slaveAddress, uint_fast8_t numBytes) {
// No point of doing anything else if there we're not a MASTER
if (busRole != BUS_ROLE_MASTER)
return 0;
if (*pTxBufferIndex > 0) {
endTransmission(false);
}
while (!sendStop)
;
// Re-initialise the rx buffer
*pRxBufferSize = numBytes;
*pRxBufferIndex = 0;
// Configure the correct slave
MAP_I2C_setSlaveAddress(module, slaveAddress);
this->slaveAddress = slaveAddress;
MAP_I2C_disableInterrupt(module, EUSCI_B_I2C_TRANSMIT_INTERRUPT0);
// Set the master into receive mode
MAP_I2C_setMode(module, EUSCI_B_I2C_RECEIVE_MODE);
// Send the START
MAP_I2C_masterReceiveStart(module);
// Send a stop early if we're only requesting one byte
// to prevent timing issues
if (numBytes == 1) {
MAP_I2C_masterReceiveMultiByteStop(module);
}
// Initialize the flag showing the status of the request
requestDone = false;
gotNAK = false;
// Wait until the request is done
while (!requestDone)
;
MAP_I2C_setMode(module, EUSCI_B_I2C_TRANSMIT_MODE);
MAP_I2C_enableInterrupt(module, EUSCI_B_I2C_TRANSMIT_INTERRUPT0);
MAP_I2C_clearInterruptFlag(module, EUSCI_B_I2C_TRANSMIT_INTERRUPT0);
// Reset the buffer
(*pRxBufferIndex) = 0;
(*pRxBufferSize) = 0;
if (gotNAK) {
return 0;
} else {
return rxReadLength;
}
}
/**
* Request data from a SLAVE as a MASTER
*/
uint8_t DWire::requestFrom( uint_fast8_t slaveAddress, uint_fast8_t numBytes )
{
// No point of doing anything else if there we're not a MASTER
if (busRole != BUS_ROLE_MASTER)
return 0;
// still something to send? Flush the TX buffer but do not send a STOP
if (*pTxBufferIndex > 0)
{
// this is a repeated start: no point in trying to receive if we fail finishing the transmission
if (endTransmission( false ))
{
return 0;
}
}
else
{
// Wait until any request is finished
timeout = TIMEOUTLIMIT;
while ( MAP_I2C_masterIsStopSent( module ) == EUSCI_B_I2C_SENDING_STOP
&& timeout)
timeout--;
}
if (!timeout)
{
/* If we get a timeout, then reset everything */
_resetBus( );
return 0;
}
// Re-initialise the rx buffer
// and make sure we never request 1 byte only
// this is an anomalous behaviour of the MSP432 related to the double
// buffering of I2C. This is a workaround.
if (numBytes == 1)
{
*pRxBufferSize = 2;
} else
{
*pRxBufferSize = numBytes;
}
*pRxBufferIndex = 0;
// Configure the correct slave
MAP_I2C_setSlaveAddress( module, slaveAddress );
this->slaveAddress = slaveAddress;
MAP_I2C_clearInterruptFlag( module,
EUSCI_B_I2C_RECEIVE_INTERRUPT0 | EUSCI_B_I2C_NAK_INTERRUPT );
MAP_I2C_enableInterrupt( module,
EUSCI_B_I2C_RECEIVE_INTERRUPT0 | EUSCI_B_I2C_NAK_INTERRUPT );
// Set the master into receive mode
MAP_I2C_setMode( module, EUSCI_B_I2C_RECEIVE_MODE );
// Initialize the flag showing the status of the request
requestDone = false;
gotNAK = false;
// Send the START
MAP_I2C_masterReceiveStart( module );
// Wait until the request is done
timeout = TIMEOUTLIMIT;
while (!requestDone && timeout)
timeout--;
if (!timeout)
{
/* If we get a timeout, then reset everything */
_resetBus( );
return 0;
}
if (gotNAK)
{
_I2CDelay( );
MAP_I2C_masterReceiveMultiByteStop( module );
return 0;
}
else
{
if (numBytes == 1)
{
return --(*pRxBufferSize);
}
else
{
return *pRxBufferSize;
}
}
}
