MSP430 I²C

The MSP430 I2C hardware on the MSP430G2553 is simple really but caused me some headaches. Anyway, this is to take you through interrupt driven and non-interrupt driven I²C comms.

Simple sequential version

Waiting for flags with a while loop is very bad... but it can sometimes be useful for debugging.

	// Initialise UCB0
	P1SEL |= BIT6 | BIT7;
	P1SEL2 |= BIT6 | BIT7;
	UCB0CTL1 |= UCSWRST;
	UCB0CTL0 = UCMST | UCMODE_3 | UCSYNC;
	UCB0CTL1 = UCSSEL_2 | UCSWRST;
	UCB0BR0 = 12;
	UCB0BR1 = 0;
	// MCP3422: 1  1  0  1 A0 A1 A2 RW (RW Bit not in UCB0I2CSA)
	UCB0I2CSA = 0x68;
	UCB0CTL1 &= ~UCSWRST;

	// Send a single byte of data
	UCB0CTL1 |= UCTR | UCTXSTT;
	while (!(IFG2 & UCB0TXIFG)); // Wait for I2C Send to Complete
	UCB0TXBUF = 0x90;
	while (!(IFG2 & UCB0TXIFG));
	UCB0CTL1 |= UCTXSTP;
	IFG2 &= ~UCB0TXIFG;