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I have been trying to develop some simple code that writes 3 bytes to a digital volume control using the I2C interface. I am using the 'B' side of the USCI module. (The 'A' side is being used as a UART. The code for the 'A' side works great! I developed some code using the 'B' side in SPI mode and that works great too!.)
The environment is as follows: MPSF2132 and DCO=1.000MHz
The processor initialization code is:
// Initialize the watchdog timer:
WDTCTL = WDTPW + WDTHOLD;
// stop the watchdog timer
// Initialize the i/o ports:
P1DIR |= 0x0f;
// set P1 [3..0] for output
P1OUT |= 0x07;
// deselect the peripheral devices
P2DIR |= 0x07;
// set P1 [2..0] for output
P2OUT |= 0x07;
// turn the LED's off
P3DIR |= 0x40;
// set P3 [6] for output
P3SEL = 0x3e;
// set P3 [5..1] for peripheral fun
// Set to use the DCO clock @ 1.000 mhz:
BCSCTL1=CALBC1_1MHZ;
// set internal DCO for 1.000 mhz
DCOCTL=CALDCO_1MHZ;
BCSCTL2=
// set to use DCO for MCLK
SELM_0+
// MCLK source select (0=DCOCLK)
DIVM_0+
// MCLK divider select (0=1)
DIVS_0;
// SMCLK divider select (0=1)
With the code below, I cannot get the USCI to do anything! (It doesn't even send the slave address.)
// WriteRegsDVC
// Routine to write a byte of configuration data and the two wiper control
// settings in the DVC registers.
// Calling Sequence:
// WriteRegsDVC (uWiper1, uWiper2);
void
{
// Initialize/configure UART B for I2C mode:
// Configuration settings
// ---------------------------------
// I2C mode enabled
// Transmitter mode selected
// Master mode selected
// Synchronous mode enabled
// 25,000 bps rate
// Slave address = 0x50
SLECT_DVC;
// select the device
UCB0CTL1=
UCSSEL1+
// clock source select (10=SMCLK)
UCSWRST;
// software reset enabled
UCB0CTL0=
UCMST+
// master mode
UCMODE1+
// I2C mode
UCMODE0+
UCSYNC;
// synchronous mode
UCB0BR0=40;
UCB0BR1=0;
// set the clock for 25,000 bps
UCB0CTL1 &= ~(UCSWRST);
// enable the I2C
UCB0CTL1 |= (UCTR+UCTXSTT);
// generate start and send address
while (!(IFG2 & UCB0TXIFG)) // wait for start to be sent
{
}
UCB0TXBUF=0x80;
// write the configuration byte
while (!(IFG2 & UCB0TXIFG)) // wait for tx buffer to be empty
{
}
UCB0TXBUF=(uWiper1 + 0x00);
// write the wiper #1 setting
while (!(IFG2 & UCB0TXIFG)) // wait for tx buffer to be empty
{
}
UCB0TXBUF=(uWiper2 + 0x40);
// write the wiper #2 setting
UCB0CTL1 |= UCTXSTP;
// set to generate stop condition
while (!(IFG2 & UCB0TXIFG)) // wait for tx buffer to be empty
{
}
DESLECT_DVC;
// deselect the device
}
I would be very grateful to anyone that can provide some insight into this problem. It really is driving me crazy.
I am assuming that the P3SEL bits should be set to reassign P3.5 -> P3.1 to the peripheral functions. (I had to do this to get the SPI code to work.)
Most of the examples for I2C communications that I have found are not for the USCI and so they are not much help.
WriteRegsDVC (UCHAR uWiper1, UCHAR uWiper2)**Attention** This is a public forum
