Danke Tobias. Ja, da hast du natürlich recht. Es handelt sich um den
Standard Code von TI. Meine einzigen Änderungen sind im ersten Post
beschrieben.
Das sieht dann in der "TI_USCI_I2C_master.c" folgendermassen aus:
//*******************************************************************
// MSP430 USCI I2C Transmitter and Receiver
//*******************************************************************
#include "msp430G2553.h" // device specific header
#include "TI_USCI_I2C_master.h"
signed char byteCtr;
unsigned char *TI_receive_field;
unsigned char *TI_transmit_field;
//----------------------------------------------------------------------
// void TI_USCI_I2C_receiveinit(unsigned char slave_address,
// unsigned char prescale)
//
// This function initializes the USCI module for master-receive
// operation.
//
// IN: unsigned char slave_address => Slave Address
// unsigned char prescale => SCL clock adjustment
//----------------------------------------------------------------------
void TI_USCI_I2C_receiveinit(unsigned char slave_address,
unsigned char prescale){
P1SEL |= SDA_PIN + SCL_PIN; // Assign I2C pins to USCI_B0
UCB0CTL1 = UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = prescale; // set prescaler
UCB0BR1 = 0;
UCB0I2CSA = slave_address; // set slave address
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
UCB0I2CIE = UCNACKIE;
IE2 = UCB0RXIE; // Enable RX interrupt
}
//---------------------------------------------------------------------
// void TI_USCI_I2C_transmitinit(unsigned char slave_address,
// unsigned char prescale)
//
// This function initializes the USCI module for master-transmit
// operation.
// IN: unsigned char slave_address => Slave Address
// unsigned char prescale => SCL clock adjustment
//---------------------------------------------------------------------
void TI_USCI_I2C_transmitinit(unsigned char slave_address,
unsigned char prescale){
P1SEL |= SDA_PIN + SCL_PIN; // Assign I2C pins to USCI_B0
UCB0CTL1 = UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = prescale; // set prescaler
UCB0BR1 = 0;
UCB0I2CSA = slave_address; // Set slave address
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
UCB0I2CIE = UCNACKIE;
IE2 = UCB0TXIE; // Enable TX ready interrupt
}
//---------------------------------------------------------------------
//void TI_USCI_I2C_receive(unsigned char byteCount,
// unsigned char *field)
// This function is used to start an I2C commuincation in
// master-receiver mode.
// IN: unsigned char byteCount => number of bytes that
// should be read
// unsigned char *field => array variable used to store
// received data
//----------------------------------------------------------------------
void TI_USCI_I2C_receive(unsigned char byteCount, unsigned char *field)
{
TI_receive_field = field;
if ( byteCount == 1 ){
byteCtr = 0 ;
__disable_interrupt();
UCB0CTL1 |= UCTXSTT; // I2C start condition
while (UCB0CTL1 & UCTXSTT); // Start condition sent?
UCB0CTL1 |= UCTXSTP; // I2C stop condition
__enable_interrupt();
} else if ( byteCount > 1 ) {
byteCtr = byteCount - 2 ;
UCB0CTL1 |= UCTXSTT; // I2C start condition
} else
while (1); // illegal parameter
}
//---------------------------------------------------------------------
//void TI_USCI_I2C_transmit(unsigned char byteCount,
// unsigned char *field)
// This function is used to start an I2C commuincation in
// master-transmit mode.
//
// IN: unsigned char byteCount => number of bytes that should be
// transmitted
// unsigned char *field => array variable. Its content
// will be sent.
//----------------------------------------------------------------------
void TI_USCI_I2C_transmit(unsigned char byteCount, unsigned char *field)
{
TI_transmit_field = field;
byteCtr = byteCount;
UCB0CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition
}
//--------------------------------------------------------------------
// unsigned char TI_USCI_I2C_slave_present(unsigned char slave_address)
//
// This function is used to look for a slave address on the I2C bus.
//
// IN: unsigned char slave_address => Slave Address
// OUT: unsigned char => 0: address was not found,
// 1: address found
//---------------------------------------------------------------------
unsigned char TI_USCI_I2C_slave_present(unsigned char slave_address){
unsigned char ie2_bak, slaveadr_bak, ucb0i2cie, returnValue;
ucb0i2cie = UCB0I2CIE; // restore old UCB0I2CIE
ie2_bak = IE2; // store IE2 register
slaveadr_bak = UCB0I2CSA; // store old slave address
UCB0I2CIE &= ~ UCNACKIE; // no NACK interrupt
UCB0I2CSA = slave_address; // set slave address
IE2 &= ~(UCB0TXIE + UCB0RXIE); // no RX or TX interrupts
__disable_interrupt();
UCB0CTL1 |= UCTR + UCTXSTT + UCTXSTP; // I2C TX, start condition
while (UCB0CTL1 & UCTXSTP); // wait for STOP condition
returnValue = !(UCB0STAT & UCNACKIFG);
__enable_interrupt();
IE2 = ie2_bak; // restore IE2
UCB0I2CSA = slaveadr_bak; // restore old slave address
UCB0I2CIE = ucb0i2cie; // restore old UCB0CTL1
return returnValue; // return whether or not
// a NACK occured
}
//---------------------------------------------------------------------
// unsigned char TI_USCI_I2C_notready()
//
// This function is used to check if there is commuincation in progress.
// OUT: unsigned char => 0: I2C bus is idle,
// 1: communication is in progress
//----------------------------------------------------------------------
---
unsigned char TI_USCI_I2C_notready(){
return (UCB0STAT & UCBBUSY);
}
#pragma vector = USCIAB0RX_VECTOR
__interrupt void USCIAB0RX_ISR(void)
{
if (UCB0STAT & UCNACKIFG){ // send STOP if slave sends NACK
UCB0CTL1 |= UCTXSTP;
UCB0STAT &= ~UCNACKIFG;
}
}
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
if (IFG2 & UCB0RXIFG){
if ( byteCtr == 0 ){
UCB0CTL1 |= UCTXSTP; // I2C stop condition
*TI_receive_field = UCB0RXBUF;
TI_receive_field++;
}
else {
*TI_receive_field = UCB0RXBUF;
TI_receive_field++;
byteCtr--;
}
}
else {
if (byteCtr == 0){
UCB0CTL1 |= UCTXSTP; // I2C stop condition
IFG2 &= ~UCB0TXIFG; // Clear USCI_B0 TX int flag
}
else {
UCB0TXBUF = *TI_transmit_field;
TI_transmit_field++;
byteCtr--;
}
}
}
