Part Number: MSP430F5529
Hi, I'm using MSP430F5529 Launchpad and are trying to talk to a slave (slave address 0x4C) using I2C. I'm trying to write 0x42 to this slave's register address 0xFF.
However, when I am probing the I2C pins, all I see are repeated [Start bit][0x4C][Write][ACK by slave]. I DON'T see this 0xFF or 0x42 anywhere on the scope. My code is below. Can you please help?
If you have another code using interrupt, feel free to share.
Thanks.
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#include <msp430.h>
unsigned char TXData;
unsigned char TXByteCtr;
int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P4SEL |= 0x06; // Assign I2C pins to USCI_B0
UCB1CTL1 |= UCSWRST; // Enable SW reset
UCB1CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB1CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB1BR0 = 120; // fSCL = SMCLK/12 = ~100kHz
UCB1BR1 = 0;
UCB1I2CSA = 0x4C; // Slave Address is 048h
UCB1CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
UCB1IE |= UCTXIE; // Enable TX interrupt
UCB1IE &= ~UCRXIE; // Disable RX interrupt
UCB1IE |= UCTXIE; // Enable TX interrupt
while (1)
{
UCB1IFG &= ~(UCTXIFG + UCRXIFG); // Clear any pending interrupts
while (UCB1CTL1 & UCTXSTP); // Ensure stop condition got sent
UCB1CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition
UCB1TXBUF = 0xFF; // Load TX buffer
UCB1TXBUF = 0x42;
UCB1CTL1 |= UCTXSTP; //I2C stop
}
}
