/**
* End the transmission and transmit the tx buffer's contents over the bus
* it returns false if succesful
*/
bool DWire::endTransmission( bool sendStop )
{
// return, if there is nothing to transmit
if (!*pTxBufferIndex)
{
return true;
}
// Wait until any ongoing (incoming) transmissions are finished
timeout = 0xFFFF;
while ( MAP_I2C_masterIsStopSent( module ) == EUSCI_B_I2C_SENDING_STOP
&& timeout)
timeout--;
if (!timeout)
{
/* If we can't start the transmission, then reset everything */
_resetBus( );
return true;
}
this->sendStop = sendStop;
gotNAK = false;
// Clear the interrupt flags and enable
MAP_I2C_clearInterruptFlag( module,
EUSCI_B_I2C_TRANSMIT_INTERRUPT0 + EUSCI_B_I2C_NAK_INTERRUPT );
MAP_I2C_enableInterrupt( module,
EUSCI_B_I2C_TRANSMIT_INTERRUPT0 + EUSCI_B_I2C_NAK_INTERRUPT );
// Set the master into transmit mode
MAP_I2C_setMode( module, EUSCI_B_I2C_TRANSMIT_MODE );
// Send the start condition and initial byte
(*pTxBufferSize) = *pTxBufferIndex;
// Send the first byte, triggering the TX interrupt
MAP_I2C_masterSendMultiByteStartWithTimeout( module, pTxBuffer[0],
TIMEOUTLIMIT );
// make sure the transmitter buffer has been flushed
timeout = TIMEOUTLIMIT;
while (*pTxBufferIndex && timeout)
timeout--;
if (!timeout)
{
_resetBus( );
return true;
}
if (gotNAK)
{
_I2CDelay( );
MAP_I2C_masterReceiveMultiByteStop( module );
}
return gotNAK;
}
/**
* Begin a transmission as a master
*/
void DWire::beginTransmission(uint_fast8_t slaveAddress) {
// Starting a transmission as a master to the slave at slaveAddress
if (busRole != BUS_ROLE_MASTER)
return;
// Wait in case a previous message is still being sent
while ( MAP_I2C_masterIsStopSent(module) == EUSCI_B_I2C_SENDING_STOP)
;
if (slaveAddress != this->slaveAddress)
_setSlaveAddress(slaveAddress);
}
/**
* 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;
}
}
}
int main(void)
{
volatile uint32_t ii;
/* Disabling the Watchdog */
MAP_WDT_A_holdTimer();
/* Select Port 1 for I2C - Set Pin 6, 7 to input Primary Module Function,
* (UCB0SIMO/UCB0SDA, UCB0SOMI/UCB0SCL).
*/
MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P1,
GPIO_PIN6 + GPIO_PIN7, GPIO_PRIMARY_MODULE_FUNCTION);
sendStopCondition = false;
sendToSlaveAddress2 = false;
/* Initializing I2C Master to SMCLK at 400kbs with no autostop */
MAP_I2C_initMaster(EUSCI_B0_MODULE, &i2cConfig);
/* Specify slave address. For start we will do our first slave address */
MAP_I2C_setSlaveAddress(EUSCI_B0_MODULE, SLAVE_ADDRESS_1);
/* Set Master in receive mode */
MAP_I2C_setMode(EUSCI_B0_MODULE, EUSCI_B_I2C_TRANSMIT_MODE);
/* Enable I2C Module to start operations */
MAP_I2C_enableModule(EUSCI_B0_MODULE);
/* Enable and clear the interrupt flag */
MAP_I2C_clearInterruptFlag(EUSCI_B0_MODULE,
EUSCI_B_I2C_TRANSMIT_INTERRUPT0 + EUSCI_B_I2C_NAK_INTERRUPT);
//Enable master Receive interrupt
MAP_I2C_enableInterrupt(EUSCI_B0_MODULE,
EUSCI_B_I2C_TRANSMIT_INTERRUPT0 + EUSCI_B_I2C_NAK_INTERRUPT);
MAP_Interrupt_enableInterrupt(INT_EUSCIB0);
while (1)
{
/* Load Byte Counter */
TXByteCtr = 4;
/* Making sure the last transaction has been completely sent out */
while (MAP_I2C_masterIsStopSent(EUSCI_B0_MODULE) == EUSCI_B_I2C_SENDING_STOP);
/* Sending the initial start condition for appropriate
* slave addresses */
if(sendToSlaveAddress2)
{
MAP_I2C_setSlaveAddress(EUSCI_B0_MODULE, SLAVE_ADDRESS_2);
}
else
{
MAP_I2C_setSlaveAddress(EUSCI_B0_MODULE, SLAVE_ADDRESS_1);
}
MAP_I2C_masterSendMultiByteStart(EUSCI_B0_MODULE, TXData++);
while(sendStopCondition == false)
{
/* Go to sleep while data is being transmitted */
MAP_Interrupt_enableSleepOnIsrExit();
MAP_PCM_gotoLPM0InterruptSafe();
}
sendStopCondition = false;
}
}