void I2CDevice::initSMBusMode()
{
// enable clock
clockEnable(true);
// disable I2C module
enable(false);
//NOTE: followed configuration is SMBus specific configuration
// timing configuration for: I2CCLK = SYSCLK = 48 MHz
// and transmission type: 100 kHz
I2C1->TIMINGR |= ( (I2C_TIMINGR_PRESC & 0xBBBBBBBB)
| (I2C_TIMINGR_SCLL & 0x13131313)
| (I2C_TIMINGR_SCLH & 0x0F0F0F0F)
| (I2C_TIMINGR_SDADEL & 0x22222222)
| (I2C_TIMINGR_SCLDEL & 0x44444444));
// rest configuration
I2C1->CR1 |= ( I2C_CR1_PECEN // enable PEC ( CRC8 byte )
// | I2C_CR1_ERRIE // enable interrupt on PEC error
// | I2C_CR1_TCIE // enable interrupt on Transfer Complete
// | I2C_CR1_TXIE // enable interrupt on Transmit buffer empty
// | I2C_CR1_RXIE // enable interrupt on Receive buffer Not Empty
);
// set the slave address to right register
setSlaveAddr();
}
// 1) doesn't work if size is > 255
// todo it is not finished. Address is sent properly, but need to examine if it works
// with real device
void I2CDevice::send(const uint8_t addr, const uint8_t * const pBuff, const size_t size)
{
if(nullptr == pBuff)
return ;
//set the Slave address
setSlaveAddr();
//set number of bytes to be transmitted
setTransferBytes(size+2); //+1 for PEC byte and +1 for the addr/command
// enable PEC functionality
I2C1->CR1 |= I2C_CR1_PECEN ;
enable(true);
// this is write transmission
I2C1->CR2 &= ~I2C_CR2_RD_WRN;
I2C1->CR2 |= I2C_CR2_AUTOEND // set autoend
| I2C_CR2_PECBYTE // PEC byte will be transmitted
| I2C_CR2_START // generate start
;
// Transmit the command / address where to store:
// - wait for TX buffer to be empty
while( !(I2C1->ISR & I2C_ISR_TXIS) ) { asm(""); }
// - write the command / address
I2C1->TXDR = addr;
// Write Data Bytes
for(size_t i = 0; i < size ; ++i)
{
// wait for NACK flag or TXIS flag
while(!(I2C1->ISR & I2C_ISR_NACKF) && !(I2C1->ISR & I2C_ISR_TXIS)) { asm(""); }
// check for NACK flag
if(I2C1->ISR & I2C_ISR_NACKF)
{
// todo report an error
// This is an error
// 1) not found address
// 2) Receiver cannot read byte
// 3) Receiver has detected error in bytes (CRC)
return ;
}
// TXIS flag - write next byte
else
{
I2C1->TXDR = pBuff[i];
}
}
// wait until STOP symbol will be detected
while(I2C1->ISR & I2C_ISR_BUSY) { asm(""); }
// disable peripheral -> clear flags
enable(false);
}
I2c::I2c(LPC_I2Cn_Type *i2c, uint8_t addr, SerialCallback callback) : m_rq(I2C_RECEIVE_BUF_SIZE), m_tq(I2C_TRANSMIT_BUF_SIZE, callback)
{
m_i2c = i2c;
m_16bit = true;
m_clearOnEnd = false;
I2C_Init(m_i2c, 100000);
setSlaveAddr(addr);
NVIC_SetPriority(SSP1_IRQn, 0); // high priority interrupt
}
void I2CDevice::read(const uint8_t addr, uint8_t * const pBuff, const size_t len)
{
// because this is an SMBus -> need to write command
// in this case the command defines the EEPROM or RAM memory and cell address
if(nullptr == pBuff)
return;
if(0 == len)
return;
// todo is this necessary on each call?
//set the Slave address
setSlaveAddr();
// 1) Transmit command
// - need to disable the PEC for writing command byte
I2C1->CR1 &= ~I2C_CR1_PECEN;
// - set number of bytes to be transmitted: 1 - only command
setTransferBytes(1);
enable(true);
// disable the autoend because need to generate the RESTART signal
I2C1->CR2 &= ~I2C_CR2_AUTOEND;
I2C1->CR2 &= ~I2C_CR2_RD_WRN; // this is a write transmission - to transmit the command
I2C1->CR2 |= I2C_CR2_START; // generate start
// Wait for TX buffer to be empty
while( !(I2C1->ISR & I2C_ISR_TXIS) );
// write the command / address
I2C1->TXDR = addr;
// Wait for Transfer Completion
while( !(I2C1->ISR & I2C_ISR_TC) );
// 2) Read bytes from device
// - set number of bytes to be received: 'len' data bytes and PEC
setTransferBytes(len + 1); // +1 for PEC byte
// - enable PEC
I2C1->CR1 |= I2C_CR1_PECEN;
I2C1->CR2 |= I2C_CR2_AUTOEND // enable autoend
| I2C_CR2_RD_WRN // this will be a read transfer
| I2C_CR2_START ; // generate 'restart' signal
// read data
for(size_t i = 0 ; i < len ; ++i)
{
while(!(I2C1->ISR & I2C_ISR_RXNE));
pBuff[i] = I2C1->RXDR;
}
// wait for the PEC byte and he end transmission
while( I2C1->ISR & I2C_ISR_BUSY );
// todo check if transmission was not broken
if( I2C1->ISR & I2C_ISR_PECERR )
{
// return PEC error
int n = 0 ;
n ++ ;
}
else
{
// return OK
int i = 0 ;
i++;
}
// disable peripheral -> clear flags
enable(false);
}
