static void i2cs_send(char c)
{
I2C_WAIT();
while( TW_STATUS != TW_ST_SLA_ACK && TW_STATUS != TW_ST_DATA_ACK ) {
I2C_ACK();
}
I2C_SEND(c);
}
// Send a n-byte data frame to an address
void i2cm_send(uint8_t slave_addr, uint8_t n, const uint8_t* data)
{
int i;
I2C_START();
// Slave address + Write bit (0)
I2C_SEND(slave_addr<<1);
// Data
for( i=0; i<n; i++ )
{
I2C_SEND(data[i]);
}
// Stop and wait
I2C_STOP();
wait_4cyc(100);
}
// Receive one data byte from an address, -1 on error
int i2cm_rcv_single(uint8_t slave_addr)
{
I2C_START();
// Slave address + Read bit (1)
I2C_SEND((slave_addr<<1)+1);
// No ACK, no data
if( TW_STATUS != TW_MR_SLA_ACK )
{
I2C_STOP();
wait_4cyc(100);
return -1;
}
// First byte: is there something to transmit?
I2C_ACK();
return TWDR;
}
/* @brief Receive data from an I2C slave.
*
* Parameters for the '>' command:
* - I2C slave address (u8)
* - data size (u8) or 0
*
* If the data size is 0, the value is read from the first data byte and is the
* number of bytes to read after this first one. This is used to read protocol
* replies from the slave.
*/
static void cmd_i2c_recv(void)
{
const uint8_t addr = init_cmd_i2c();
if( addr == 0 ) {
return; // reply sent by init_cmd_i2c()
}
uint8_t size = recv_u8();
// poll the slave
do I2CM_START(); while( TW_STATUS != TW_START );
// slave address + Read bit (1)
I2C_SEND((addr<<1)+1);
#ifndef DISABLE_STRICT_CHECKS
if( TW_STATUS != TW_MR_SLA_ACK && TW_STATUS != TW_MR_SLA_NACK ) {
I2CM_STOP();
goto slave_i2c_error;
}
#endif
if( size == 0 ) {
// read the size in the first byte
I2C_ACK();
size = TWDR;
reply_success(size+1);
send_u8(size);
} else {
reply_success(size);
}
while( size-- != 1 ) {
I2C_ACK();
const uint8_t c = TWDR;
send_u8(c);
}
I2C_NACK();
send_u8( TWDR );
I2CM_STOP();
return;
#ifndef DISABLE_STRICT_CHECKS
slave_i2c_error:
reply_error(STATUS_I2C_ERROR);
return;
#endif
}
// Receive a frame from an address
// Slave must respect the i2c_ryder protocol : first byte tells if there are
// data to transmit or not
// Return number of read bytes
uint8_t i2cm_rcv(uint8_t slave_addr, uint8_t n, uint8_t* data)
{
int i;
I2C_START();
// Slave address + Read bit (1)
I2C_SEND((slave_addr<<1)+1);
// No ACK, no data
if( TW_STATUS != TW_MR_SLA_ACK )
{
I2C_STOP();
wait_4cyc(100);
return 0;
}
// First byte: is there something to transmit?
I2C_ACK();
if( TWDR == 0 )
{
I2C_NACK();
I2C_STOP();
wait_4cyc(100);
return 0;
}
// Read all data
for( i=0; i<n; i++ )
{
I2C_ACK();
data[i] = TWDR;
}
I2C_NACK();
I2C_STOP();
wait_4cyc(100);
return 1;
}
/** @brief Send data to an I2C slave.
*
* Parameters:
* - I2C slave address (u8)
* - data size (u16)
* - data to send
*
* If the data size is 0 an empty frame is sent.
* This can be used to synchronize the slave.
*
* @warning Since UART data is not bufferised, if slave is too long to UART
* buffer overflows and the server will wait forever its input data.
*/
static void cmd_i2c_send(void)
{
const uint8_t addr = init_cmd_i2c();
if( addr == 0 ) {
return; // reply sent by init_cmd_i2c()
}
// write frame
uint16_t size = recv_u16();
// poll the slave
do I2CM_START(); while( TW_STATUS != TW_START );
// slave address + Write bit (0)
I2C_SEND(addr<<1);
#ifndef DISABLE_STRICT_CHECKS
uint8_t tw_status_copy = TW_STATUS;
if( tw_status_copy == TW_MT_SLA_NACK ) {
goto i2c_stop_slave_i2c_error;
}
if( tw_status_copy != TW_MT_SLA_ACK ) {
goto slave_i2c_error;
}
#endif
if( size != 0 ) {
#ifndef DISABLE_STRICT_CHECKS
tw_status_copy = TW_STATUS;
if( tw_status_copy == TW_MT_SLA_NACK ) {
goto i2c_stop_slave_i2c_error;
}
if( tw_status_copy != TW_MT_SLA_ACK ) {
goto slave_i2c_error;
}
#endif
// transfer data
while( size-- != 1 ) {
const uint8_t c = recv_u8();
I2C_SEND(c);
#ifndef DISABLE_STRICT_CHECKS
tw_status_copy = TW_STATUS;
if( tw_status_copy != TW_MT_DATA_ACK ) {
goto i2c_stop_slave_i2c_error;
}
#endif
}
const uint8_t c_last = recv_u8();
I2C_SEND_LAST(c_last);
#ifndef DISABLE_STRICT_CHECKS
tw_status_copy = TW_STATUS;
if( tw_status_copy != TW_MT_DATA_ACK && tw_status_copy != TW_MT_DATA_NACK ) {
goto i2c_stop_slave_i2c_error;
}
#endif
}
I2CM_STOP();
reply_success(0);
return;
#ifndef DISABLE_STRICT_CHECKS
i2c_stop_slave_i2c_error:
I2CM_STOP();
slave_i2c_error:
reply_error(STATUS_I2C_ERROR);
return;
#endif
}
