//-----------------------------------------------------------------------------
// unsigned char i2c_slave_present(unsigned char slave_address)
//
// This function is used to look for a slave address on the I2C bus.
// It sends a START and STOP condition back-to-back and wait for an ACK from the slave
//
// IN: unsigned char slave_address => Slave Address
// OUT: unsigned char => 0: address was not found,
// 1: address found
//-----------------------------------------------------------------------------
unsigned char i2c_slave_present(int bus_num, unsigned char slave_address) {
unsigned char uc1ie_bak, slaveadr_bak, ucb1i2cie_bak, returnValue;
//store state
ucb1i2cie_bak = *i2c_control.i2cie[bus_num]; // store *i2c_control.i2cie[bus_num] register
uc1ie_bak = *i2c_control.ie[bus_num]; // store UC1IE register
slaveadr_bak = *i2c_control.i2csa[bus_num]; // store old slave address
//start i2c
while ( i2c_busy(bus_num) );
i2c_init_transmit(bus_num,slave_address);
//
*i2c_control.i2cie[bus_num] &= ~UCNACKIE; // no NACK interrupt
*i2c_control.i2csa[bus_num] = slave_address; // set slave address
*i2c_control.ie[bus_num] &= ~(i2c_control.ietx[bus_num] + i2c_control.ierx[bus_num]); // no RX or TX interrupts
__disable_interrupt();
*i2c_control.ctl1[bus_num] |= UCTR + UCTXSTT + UCTXSTP; // transmitter, start and stop condition
while (*i2c_control.ctl1[bus_num] & UCTXSTP); // wait for STOP condition
returnValue = !(*i2c_control.stat[bus_num] & UCNACKIFG); // 0 if an ACK was received
__enable_interrupt();
//restore state
*i2c_control.ie[bus_num] = uc1ie_bak; // restore IE2
*i2c_control.i2csa[bus_num] = slaveadr_bak; // restore old slave address
*i2c_control.i2cie[bus_num] = ucb1i2cie_bak; // restore old UCB0CTL1
return returnValue; // return whether or not
}
void i2c_write_register(uint8_t bus_num, uint8_t slave_addr, uint8_t reg_addr, uint8_t reg_setting) {
uint8_t i2c_packet[2] = {reg_addr, reg_setting};
i2c_init_transmit(bus_num,slave_addr);
while ( i2c_busy(bus_num) );
i2c_transmit(bus_num,sizeof(i2c_packet),i2c_packet);
while ( i2c_busy(bus_num) );
__delay_cycles(I2C_BUS_FREE_TIME);
}
/**
data contains the register as a first element if needed. Note that i2c is a
transport mechanism and whether there is a register as a first param or not is
app/device dependent
*/
void i2c_write_register(uint8_t bus_num, uint8_t slave_addr, uint8_t length, uint8_t* data) {
i2c_init_transmit(bus_num,slave_addr);
while( i2c_busy(bus_num) );
i2c_transmit(bus_num,length,data);
while( i2c_busy(bus_num) );
__delay_cycles(I2C_BUS_FREE_TIME);
}
void i2c_read_registers(uint8_t bus_num, uint8_t slave_addr, uint8_t reg_addr, uint8_t numBytes, uint8_t* spaceToWrite) {
uint8_t i2c_packet[1] = {reg_addr};
//transmit reg address to gyro
i2c_init_transmit(bus_num,slave_addr);
while ( i2c_busy(bus_num) );
i2c_transmit(bus_num,sizeof(i2c_packet),i2c_packet);
while ( i2c_busy(bus_num) );
__delay_cycles(I2C_BUS_FREE_TIME);
//read what gyro has to say
i2c_init_receive(bus_num,slave_addr);
while ( i2c_busy(bus_num) );
i2c_receive(bus_num,numBytes,spaceToWrite);
while ( i2c_busy(bus_num) );
__delay_cycles(I2C_BUS_FREE_TIME);
}
