i2c_msp432.cpp

/*
 * spi_msp432.cpp
 *
 *  Created on: 14.06.2016
 *      Author: Andreas Terstegge
 */
 
#include <cassert>
#include "i2c_msp432.h"
 
// If existing, use the global SubsystemMasterClock. If not, use our own
// copy of the SystemCoreClock, assuming that MCLK equals SMCLK ...
uint32_t I2C_CLK = SystemCoreClock;
extern uint32_t SubsystemMasterClock __attribute__((weak,alias("I2C_CLK")));
 
 
i2c_msp432::i2c_msp432(EUSCI_B_Type *mod, uint16_t mode)
: _initialized(false), _EUSCI(mod), _mode(mode)
{
    // Configure hardware characteristics
    if (mod==EUSCI_B0) {
        _sda.setGpio (PORT_PIN(1, 6));
        _scl.setGpio (PORT_PIN(1, 7));
    } else if (mod==EUSCI_B1) {
        _sda.setGpio (PORT_PIN(6, 4));
        _scl.setGpio (PORT_PIN(6, 5));
    } else if (mod==EUSCI_B2) {
        _sda.setGpio (PORT_PIN(3, 6));
        _scl.setGpio (PORT_PIN(3, 7));
    } else if (mod==EUSCI_B3) {
        _sda.setGpio (PORT_PIN(10, 2));
        _scl.setGpio (PORT_PIN(10, 3));
    }
    else assert(false);
}
 
 
i2c_msp432::~i2c_msp432() {
    // Wait for pending operations
    while (_EUSCI->STATW & EUSCI_B_STATW_BBUSY);
 
    // Reset CTLW0 register to default values
    // (EUSCI_B is in reset state)
    _EUSCI->CTLW0 = EUSCI_B_CTLW0_SWRST;
 
    // De-configure the digital lines
    _sda.setSEL(0); _sda.setMode(GPIO::INPUT);
    _scl.setSEL(0); _scl.setMode(GPIO::INPUT);
}
 
void i2c_msp432::initialize() {
     // Reset CTLW0 register to default values
     // (EUSCI is in reset state)
     _EUSCI->CTLW0 = EUSCI_B_CTLW0_SWRST;
 
     // Configure I2C port
     _EUSCI->CTLW0 |= (_mode | EUSCI_B_CTLW0_MODE_3);
     _EUSCI->CTLW1  = 0;
 
     // Set i2c clock to default 100 kHz
     _EUSCI->BRW = SubsystemMasterClock / 100000;
 
     // Disable interrupts
     _EUSCI->IE = 0;
 
     // Configure the digital RX/TX lines
     _sda.setMode(GPIO::INPUT | GPIO::PULLUP); _sda.setSEL(1);
     _scl.setMode(GPIO::INPUT | GPIO::PULLUP); _scl.setSEL(1);
 
     // Finally enable EUSCI module
     _EUSCI->CTLW0 &= ~EUSCI_B_CTLW0_SWRST;
 
     // Set 'initialized' flag
     _initialized = true;
}
 
int16_t i2c_msp432::i2cRead (uint16_t addr, uint8_t *rxbuf, uint16_t len, bool sendStop) {
    if (!_initialized) initialize();
    // Check for len 0 because the sendStart/Stop
    // routines might hang in this case.
    if (!len) return 0;
    // clear interrupt status and set slave address
    int16_t i = _EUSCI->RXBUF;
    _EUSCI->IFG = 0;
    _EUSCI->I2CSA = addr;
    set_receiver();
    send_START();
    for (i=0; i < len; ++i) {
        // check for last byte to receive
        if ((i+1) == len) {
            if (sendStop) send_STOP();
            else _EUSCI->CTLW0 |= EUSCI_B_CTLW0_TXSTT;
        }
        // Wait until data available
        while(!(_EUSCI->IFG & (EUSCI_B_IFG_RXIFG0 | EUSCI_B_IFG_NACKIFG)));
        // Check NAK condition
        if (_EUSCI->IFG & EUSCI_B_IFG_NACKIFG) {
            if (sendStop) send_STOP();
            return i-1;
        }
        // read the data
        rxbuf[i] = _EUSCI->RXBUF;
    }
    return i;
}
 
int16_t i2c_msp432::i2cWrite(uint16_t addr, uint8_t *txbuf, uint16_t len, bool sendStop) {
    if (!_initialized) initialize();
    // Check for len 0 because the sendStart/Stop
    // routines might hang in this case.
    if (!len) return 0;
    // clear interrupt status and set slave address
    _EUSCI->IFG   = 0;
    _EUSCI->I2CSA = addr;
    set_transmitter();
    send_START();
    int16_t i = 0;
    for (i=0; i < len; ++i) {
        // Place character in buffer
        _EUSCI->TXBUF = txbuf[i];
        // Wait until byte has been sent or NACK
        while(!(_EUSCI->IFG & (EUSCI_B_IFG_TXIFG0 | EUSCI_B_IFG_NACKIFG)));
        // Check NAK condition (also if wrong address!)
        if (_EUSCI->IFG & EUSCI_B_IFG_NACKIFG) {
            if (sendStop) send_STOP();
            return i-1;
        }
    }
    if (sendStop) send_STOP();
    return i;
}
 
void i2c_msp432::setSpeed(uint32_t baud) {
    if (!_initialized) initialize();
    _EUSCI->BRW = SubsystemMasterClock / baud;
}
 
//void i2c_msp432::send_ADR_ACK() {
//  _EUSCI->CTLW0 |= EUSCI_B_CTLW0_TXACK;
//}
//
//void i2c_msp432::send_ADR_NACK() {
//  _EUSCI->CTLW0 &= ~EUSCI_B_CTLW0_TXACK;
//}
 
void i2c_msp432::set_receiver() {
    _EUSCI->CTLW0 &= ~EUSCI_B_CTLW0_TR;
}
 
void i2c_msp432::set_transmitter() {
    _EUSCI->CTLW0 |= EUSCI_B_CTLW0_TR;
}
 
//void i2c_msp432::send_ACK() {
//  _EUSCI->CTLW0 &= ~EUSCI_B_CTLW0_TXNACK;
//}
//
//void i2c_msp432::send_NACK() {
//  _EUSCI->CTLW0 |= EUSCI_B_CTLW0_TXNACK;
//}
 
void i2c_msp432::send_START() {
    _EUSCI->CTLW0 |= EUSCI_B_CTLW0_TXSTT;
    // Wait until the START condition has been sent
    while(_EUSCI->CTLW0 & EUSCI_B_CTLW0_TXSTT) ;
}
 
void i2c_msp432::send_STOP() {
    _EUSCI->CTLW0 |= EUSCI_B_CTLW0_TXSTP;
    // Wait until the STOP condition has been sent
    while (_EUSCI->CTLW0 & EUSCI_B_CTLW0_TXSTP);
}