MSP432P401R: I2C Wrong Address

Hi Michael,

You indicate that communications with the MAX 30101 works, but, if you use the MAP_I2C_masterSendMultiByteStart(), it doesn't, correct?

What do you use when it works?

Are you using  MAP_I2C_setSlaveAddress(EUSCI_B0_BASE, SLAVE_ADDRESS) to set the address?

I use that in my configuration.

This is my configuration

static const eUSCI_I2C_MasterConfig i2cConfig =
{
EUSCI_B_I2C_CLOCKSOURCE_SMCLK,
12000000,
EUSCI_B_I2C_SET_DATA_RATE_400KBPS,
0,
EUSCI_B_I2C_NO_AUTO_STOP
};

void initI2C(void){
MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P6, GPIO_PIN0, 0);
MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P6, GPIO_PIN4 | GPIO_PIN5, GPIO_PRIMARY_MODULE_FUNCTION);
MAP_I2C_initMaster(EUSCI_B1_BASE, &i2cConfig);//Initialize Master
MAP_I2C_setSlaveAddress(EUSCI_B1_BASE, SLAVE_ADDRESS);//Set slave address of MAX30101
MAP_I2C_setMode(EUSCI_B1_BASE, EUSCI_B_I2C_TRANSMIT_MODE);
MAP_I2C_enableModule(EUSCI_B1_BASE); //Enable module
}

uint8_t read_seq(uint8_t reg){
uint_fast16_t status;

status = MAP_I2C_getInterruptStatus(EUSCI_B1_BASE, EUSCI_B_I2C_NAK_INTERRUPT+EUSCI_B_I2C_STOP_INTERRUPT+EUSCI_B_I2C_TRANSMIT_INTERRUPT0+EUSCI_B_I2C_RECEIVE_INTERRUPT0);
MAP_I2C_clearInterruptFlag(EUSCI_B1_BASE, status);
//Tried to get this to work for hours
//Found solution at e2e.ti.com/.../msp432p401r-in-i2c-master-how-to-send-one-byte-to-slave-repeat-start-and-read-one-byte-by-interrupt-method
MAP_I2C_masterSendMultiByteStart(EUSCI_B1_BASE, reg);

while((UCB1IFG & EUSCI_B_IFG_TXIFG) == 0);
EUSCI_B1->IFG &= ~(EUSCI_B_IFG_TXIFG);

__delay_cycles(300);

//clear the TR bit to setup master as receiver
EUSCI_B1->CTLW0 &= ~(EUSCI_B_CTLW0_TR);
I2C_masterSendStart(EUSCI_B1_BASE);
// wait for address to be sent
// while(!MAP_I2C_masterIsStartSent(EUSCI_B1_BASE));
while((EUSCI_B1->CTLW0 & EUSCI_B_CTLW0_TXSTT) == 0);
// set stop immediately to ensure only one byte is read
EUSCI_B1->CTLW0 |= EUSCI_B_CTLW0_TXSTP;
// poll RX flag
while(!(EUSCI_B1->IFG & EUSCI_B_IFG_RXIFG0));
// Read from Receive buffer
uint8_t RXData = EUSCI_B1->RXBUF;
// ensure I2C transaction has completed
while (MAP_I2C_masterIsStopSent(EUSCI_B1_BASE) == EUSCI_B_I2C_SENDING_STOP);
return RXData;

}