/*
* Init SPI on USCI UCB0 as UCA0 is used for UART (printf's)
*/
void
spi_init(void)
{
#if _MCU_ == 2553
#if USE_RADIO
/*
* From TIs users manual
* The recommended USCI initialization/re-configuration process is:
*/
/** 1. Set UCSWRST (BIS.B #UCSWRST,&UCxCTL1)*/
UCB0CTL1 = UCSWRST;
/** 2. Initialize all USCI registers with UCSWRST=1 (including UCxCTL1)*/
UCB0CTL0 |= UCCKPH | UCMSB | UCMST | UCSYNC | UCMODE_0;
UCB0CTL1 |= UCSSEL_2;
/** 3. Configure ports*/
SPI_PORT(SEL) |= SPI_MISO | SPI_MOSI | SPI_SCL;
SPI_PORT(SEL2) |= SPI_MISO | SPI_MOSI | SPI_SCL;
/** 4. Clear UCSWRST via software (BIC.B #UCSWRST,&UCxCTL1)*/
UCB0CTL1 &= ~UCSWRST;
/** 5. Enable interrupts (optional) via UCxRXIE and/or UCxTXIE*/
#endif /* USE_RADIO */
#endif /* _MCU_ == 2553 */
}
/**
* For talking to the MCP4822 DAC
*/
void DAC_updateVoltage(uint16_t channel, uint16_t value) {
// Validate channel selection
if(channel <= 1) {
// Cap value to 12 bits only
if(value > 0x0FFF) {
value = 0x0FFF;
}
char txBuf[2];
uint16_t cmd = 0x3000 | (value & 0x0FFF);
if(channel) cmd |= 0x8000;
txBuf[1] = cmd & 0x00FF;
txBuf[0] = __swap_bytes(cmd) & 0x00FF;
CLR_BITS(SPI_PORT(OUT),SSEL | nLDAC); // CS~ falling edge, hold nLDAC low
SPI_send(txBuf, 2);
SET_BITS(SPI_PORT(OUT),SSEL); // CS~ Rising edge. Because nLDAC is low, DAC output changes on rising CS~ edge.
}
}
