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/*
* i2c.h
*
* Created on: 28 de abr de 2017
* Author: helio.capella
*
* Based on msp430g2xx3_uscib0_i2c_12.c by D. Dang
*
* Modified by tcsullivan:
* 04/29: Modified pin macros to work with project
*/
#include <msp430.h>
#include "i2c.h"
#include "board.h"
#define I2CSEL P1SEL
#define I2CSEL2 P1SEL2
#define I2CSCL (TEMP_SCL)
#define I2CSDA (TEMP_SDA)
void I2C_init(uint8_t slaveAddress){
// Port Configuration
I2CSEL |= I2CSDA + I2CSCL; // Assign I2C pins to USCI_B0
I2CSEL2|= I2CSDA + I2CSCL; // Assign I2C pins to USCI_B0
// isRx = 0; // State variable - possibly useless
//USCI Configuration
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
//Set USCI Clock Speed
UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB0BR1 = 0;
//Set Slave Address and Resume operation
UCB0I2CSA = slaveAddress; // Slave Address passed as parameter
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
}
void I2C_write(uint8_t ByteCtr, uint8_t *TxData) {
__disable_interrupt();
// isRx = 0;
//Interrupt management
IE2 &= ~UCB0RXIE; // Disable RX interrupt
// while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
IE2 |= UCB0TXIE; // Enable TX interrupt
//Pointer to where data is stored to be sent
PTxData = (uint8_t *) TxData; // TX array start address
TxByteCtr = ByteCtr; // Load TX byte counter
//Send start condition
// while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
UCB0CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition
__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
while (UCB0CTL1 & UCTXSTP);
}
void I2C_read(uint8_t ByteCtr, volatile uint8_t *RxData) {
__disable_interrupt();
// isRx = 1;
//Interrupt management
IE2 &= ~UCB0TXIE; // Disable TX interrupt
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
IE2 |= UCB0RXIE; // Enable RX interrupt
//Pointer to where data will be stored
PRxData = (uint8_t *) RxData; // Start of RX buffer
RxByteCtr = ByteCtr; // Load RX byte counter
//while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
//If only 1 byte will be read send stop signal as soon as it starts transmission
if(RxByteCtr == 1){
UCB0CTL1 |= UCTXSTT; // I2C start condition
while (UCB0CTL1 & UCTXSTT); // Start condition sent?
UCB0CTL1 |= UCTXSTP; // I2C stop condition
__enable_interrupt();
} else {
UCB0CTL1 |= UCTXSTT; // I2C start condition
}
__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
}
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCIAB0TX_VECTOR))) USCIAB0TX_ISR (void)
#else
#error Compiler not supported!
#endif
{
if(IFG2 & UCB0RXIFG){ // Receive In
if (RxByteCtr == 1)
{
*PRxData = UCB0RXBUF; // Move final RX data to PRxData
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
else
{
*PRxData++ = UCB0RXBUF; // Move RX data to address PRxData
if (RxByteCtr == 2) // Check whether byte is second to last to be read to send stop condition
UCB0CTL1 |= UCTXSTP;
__no_operation();
}
RxByteCtr--; // Decrement RX byte counter
}
else{ // Master Transmit
if (TxByteCtr) // Check TX byte counter
{
UCB0TXBUF = *PTxData; // Load TX buffer
PTxData++;
TxByteCtr--; // Decrement TX byte counter
}
else
{
UCB0CTL1 |= UCTXSTP; // I2C stop condition
IFG2 &= ~UCB0TXIFG; // Clear USCI_B0 TX int flag
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
}
}
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