0,0 → 1,530 |
#include "defines.h" |
#include "I2C2.h" |
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static I2C2_DATA *i2c_data_p; |
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// Set up the data structures for the base_I2C.code |
// Should be called once before any i2c routines are called |
void I2C2_Init(I2C2_DATA *data) { |
i2c_data_p = data; |
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i2c_data_p->buffer_in_len = 0; |
i2c_data_p->buffer_in_len_tmp = 0; |
i2c_data_p->buffer_in_read_ind = 0; |
i2c_data_p->buffer_in_write_ind = 0; |
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i2c_data_p->buffer_out_ind = 0; |
i2c_data_p->buffer_out_len = 0; |
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i2c_data_p->operating_mode = 0; |
i2c_data_p->operating_state = I2C_IDLE; |
i2c_data_p->return_status = 0; |
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i2c_data_p->slave_in_last_byte = 0; |
i2c_data_p->slave_sending_data = 0; |
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i2c_data_p->master_dest_addr = 0; |
i2c_data_p->master_status = I2C_MASTER_IDLE; |
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// Enable I2C interrupt |
PIE4bits.SSP2IE = 1; |
} |
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// Setup the PIC to operate as a master. |
void I2C2_Configure_Master(uint8_t speed) { |
i2c_data_p->operating_mode = I2C_MODE_MASTER; |
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I2C_2_CLK_TRIS = 1; |
I2C_2_DAT_TRIS = 1; |
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SSP2STAT = 0x0; |
SSP2CON1 = 0x0; |
SSP2CON2 = 0x0; |
SSP2CON1bits.SSPM = 0x8; // I2C Master Mode |
if (speed == 0x01) { |
SSP2ADD = 0x13; // Operate at 400KHz (32MHz) |
SSP2STATbits.SMP = 1; // Disable Slew Rate Control |
} else if (speed == 0x02) { |
SSP2ADD = 0x07; // Operate at 1Mhz (32Mhz) |
SSP2STATbits.SMP = 1; // Disable Slew Rate Control |
} else { |
SSP2ADD = 0x4F; // Operate at 100KHz (32MHz) |
SSP2STATbits.SMP = 0; // Enable Slew Rate Control |
} |
SSP2CON1bits.SSPEN = 1; // Enable MSSP2 Module |
} |
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// Sends length number of bytes in msg to specified address (no R/W bit) |
void I2C2_Master_Send(uint8_t address, uint8_t length, uint8_t *msg) { |
uint8_t i; |
if (length == 0) |
return; |
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// Copy message to send into buffer and save length/address |
for (i = 0; i < length; i++) { |
i2c_data_p->buffer_in[i] = msg[i]; |
} |
i2c_data_p->buffer_in_len = length; |
i2c_data_p->master_dest_addr = address; |
i2c_data_p->buffer_in_read_ind = 0; |
i2c_data_p->buffer_in_write_ind = 0; |
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// Change status to 'next' operation |
i2c_data_p->operating_state = I2C_SEND_ADDR; |
i2c_data_p->master_status = I2C_MASTER_SEND; |
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// Generate start condition |
SSP2CON2bits.SEN = 1; |
} |
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// Reads length number of bytes from address (no R/W bit) |
void I2C2_Master_Recv(uint8_t address, uint8_t length) { |
if (length == 0) |
return; |
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// Save length and address to get data from |
i2c_data_p->buffer_in_len = length; |
i2c_data_p->master_dest_addr = address; |
i2c_data_p->buffer_in_read_ind = 0; |
i2c_data_p->buffer_in_write_ind = 0; |
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// Change status to 'next' operation |
i2c_data_p->operating_state = I2C_SEND_ADDR; |
i2c_data_p->master_status = I2C_MASTER_RECV; |
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// Generate start condition |
SSP2CON2bits.SEN = 1; |
} |
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// Writes msg to address then reads length number of bytes from address |
void I2C2_Master_Restart(uint8_t address, uint8_t msg, uint8_t length) { |
uint8_t c; |
if (length == 0) { |
c = msg; |
I2C2_Master_Send(address, 1, &c); |
return; |
} |
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// Save length and address to get data from |
i2c_data_p->buffer_in[0] = msg; |
i2c_data_p->buffer_in_len = length; |
i2c_data_p->master_dest_addr = address; |
i2c_data_p->buffer_in_read_ind = 0; |
i2c_data_p->buffer_in_write_ind = 0; |
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// Change status to 'next' operation |
i2c_data_p->operating_state = I2C_SEND_ADDR; |
i2c_data_p->master_status = I2C_MASTER_RESTART; |
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// Generate start condition |
SSP2CON2bits.SEN = 1; |
} |
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// Setup the PIC to operate as a slave. The address must not include the R/W bit |
void I2C2_Configure_Slave(uint8_t addr) { |
i2c_data_p->operating_mode = I2C_MODE_SLAVE; |
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// Ensure the two lines are set for input (we are a slave) |
I2C_2_CLK_TRIS = 1; |
I2C_2_DAT_TRIS = 1; |
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SSP2ADD = addr << 1; // Set the slave address |
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SSP2STAT = 0x0; |
SSP2CON1 = 0x0; |
SSP2CON2 = 0x0; |
SSP2CON1bits.SSPM = 0xE; // Enable Slave 7-bit w/ start/stop interrupts |
SSP2STATbits.SMP = 1; // Slew Off |
SSP2CON2bits.SEN = 1; // Enable clock-stretching |
SSP2CON1bits.SSPEN = 1; // Enable MSSP2 Module |
} |
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void I2C2_Interrupt_Handler() { |
// Call interrupt depending on which mode we are operating in |
if (i2c_data_p->operating_mode == I2C_MODE_MASTER) { |
I2C2_Interrupt_Master(); |
} else if (i2c_data_p->operating_mode == I2C_MODE_SLAVE) { |
I2C2_Interrupt_Slave(); |
} |
} |
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// An internal subroutine used in the master version of the i2c_interrupt_handler |
void I2C2_Interrupt_Master() { |
// If we are in the middle of sending data |
if (i2c_data_p->master_status == I2C_MASTER_SEND) { |
switch (i2c_data_p->operating_state) { |
case I2C_IDLE: |
break; |
case I2C_SEND_ADDR: |
// Send the address with read bit set |
i2c_data_p->operating_state = I2C_CHECK_ACK_SEND; |
SSP2BUF = (i2c_data_p->master_dest_addr << 1) | 0x0; |
break; |
case I2C_CHECK_ACK_SEND: |
// Check if ACK is received or not |
if (!SSP2CON2bits.ACKSTAT) { |
// If an ACK is received, send next byte of data |
if (i2c_data_p->buffer_in_read_ind < i2c_data_p->buffer_in_len) { |
SSP2BUF = i2c_data_p->buffer_in[i2c_data_p->buffer_in_read_ind]; |
i2c_data_p->buffer_in_read_ind++; |
} else { |
// If no more data is to be sent, send stop bit |
i2c_data_p->operating_state = I2C_IDLE; |
SSP2CON2bits.PEN = 1; |
i2c_data_p->master_status = I2C_MASTER_IDLE; |
i2c_data_p->return_status = I2C_SEND_OK; |
} |
} else { |
// If a NACK is received, stop transmission and send error |
i2c_data_p->operating_state = I2C_IDLE; |
SSP2CON2bits.PEN = 1; |
i2c_data_p->master_status = I2C_MASTER_IDLE; |
i2c_data_p->return_status = I2C_SEND_FAIL; |
} |
break; |
} |
// If we are in the middle of receiving data |
} else if (i2c_data_p->master_status == I2C_MASTER_RECV) { |
switch (i2c_data_p->operating_state) { |
case I2C_IDLE: |
break; |
case I2C_SEND_ADDR: |
// Send address with write bit set |
i2c_data_p->operating_state = I2C_CHECK_ACK_RECV; |
uint8_t tmp = (i2c_data_p->master_dest_addr << 1); |
tmp |= 0x01; |
SSP2BUF = tmp; |
break; |
case I2C_CHECK_ACK_RECV: |
// Check if ACK is received |
if (!SSP2CON2bits.ACKSTAT) { |
// If an ACK is received, set module to receive 1 byte of data |
i2c_data_p->operating_state = I2C_RCV_DATA; |
SSP2CON2bits.RCEN = 1; |
} else { |
// If a NACK is received, stop transmission and send error |
i2c_data_p->operating_state = I2C_IDLE; |
SSP2CON2bits.PEN = 1; |
i2c_data_p->master_status = I2C_MASTER_IDLE; |
i2c_data_p->return_status = I2C_RECV_FAIL; |
} |
break; |
case I2C_RCV_DATA: |
// On receive, save byte into buffer |
// TODO: Handle I2C buffer overflow |
i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = SSP2BUF; |
i2c_data_p->buffer_in_write_ind++; |
if (i2c_data_p->buffer_in_write_ind < i2c_data_p->buffer_in_len) { |
// If we still need to read, send an ACK to the slave |
i2c_data_p->operating_state = I2C_REQ_DATA; |
SSP2CON2bits.ACKDT = 0; // ACK |
SSP2CON2bits.ACKEN = 1; |
} else { |
// If we are done reading, send an NACK to the slave |
i2c_data_p->operating_state = I2C_SEND_STOP; |
SSP2CON2bits.ACKDT = 1; // NACK |
SSP2CON2bits.ACKEN = 1; |
} |
break; |
case I2C_REQ_DATA: |
// Set module to receive one byte of data |
i2c_data_p->operating_state = I2C_RCV_DATA; |
SSP2CON2bits.RCEN = 1; |
break; |
case I2C_SEND_STOP: |
// Send the stop bit and copy message to send to Main() |
i2c_data_p->operating_state = I2C_IDLE; |
SSP2CON2bits.PEN = 1; |
i2c_data_p->master_status = I2C_MASTER_IDLE; |
i2c_data_p->return_status = I2C_RECV_OK; |
break; |
} |
} else if (i2c_data_p->master_status == I2C_MASTER_RESTART) { |
switch (i2c_data_p->operating_state) { |
case I2C_IDLE: |
break; |
case I2C_SEND_ADDR: |
// Send the address with read bit set |
i2c_data_p->operating_state = I2C_CHECK_ACK_SEND; |
SSP2BUF = (i2c_data_p->master_dest_addr << 1) | 0x0; |
break; |
case I2C_CHECK_ACK_SEND: |
// Check if ACK is received or not |
if (!SSP2CON2bits.ACKSTAT) { |
// If an ACK is received, send first byte of data |
SSP2BUF = i2c_data_p->buffer_in[0]; |
i2c_data_p->operating_state = I2C_CHECK_ACK_RESTART; |
} else { |
// If a NACK is received, stop transmission and send error |
i2c_data_p->operating_state = I2C_IDLE; |
SSP2CON2bits.PEN = 1; |
i2c_data_p->master_status = I2C_MASTER_IDLE; |
i2c_data_p->return_status = I2C_SEND_FAIL; |
} |
break; |
case I2C_CHECK_ACK_RESTART: |
if (!SSP2CON2bits.ACKSTAT) { |
SSP2CON2bits.RSEN = 1; |
i2c_data_p->operating_state = I2C_SEND_ADDR_2; |
} else { |
// If a NACK is received, stop transmission and send error |
i2c_data_p->operating_state = I2C_IDLE; |
SSP2CON2bits.PEN = 1; |
i2c_data_p->master_status = I2C_MASTER_IDLE; |
i2c_data_p->return_status = I2C_SEND_FAIL; |
} |
break; |
case I2C_SEND_ADDR_2: |
// Send the address with read bit set |
i2c_data_p->operating_state = I2C_CHECK_ACK_RECV; |
uint8_t tmp = (i2c_data_p->master_dest_addr << 1); |
tmp |= 0x01; |
SSP2BUF = tmp; |
break; |
case I2C_CHECK_ACK_RECV: |
// Check if ACK is received |
if (!SSP2CON2bits.ACKSTAT) { |
// If an ACK is received, set module to receive 1 byte of data |
i2c_data_p->operating_state = I2C_RCV_DATA; |
SSP2CON2bits.RCEN = 1; |
} else { |
// If a NACK is received, stop transmission and send error |
i2c_data_p->operating_state = I2C_IDLE; |
SSP2CON2bits.PEN = 1; |
i2c_data_p->master_status = I2C_MASTER_IDLE; |
i2c_data_p->return_status = I2C_RECV_FAIL; |
} |
break; |
case I2C_RCV_DATA: |
// On receive, save byte into buffer |
// TODO: Handle I2C buffer overflow |
i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = SSP2BUF; |
i2c_data_p->buffer_in_write_ind++; |
if (i2c_data_p->buffer_in_write_ind < i2c_data_p->buffer_in_len) { |
// If we still need to read, send an ACK to the slave |
i2c_data_p->operating_state = I2C_REQ_DATA; |
SSP2CON2bits.ACKDT = 0; // ACK |
SSP2CON2bits.ACKEN = 1; |
} else { |
// If we are done reading, send an NACK to the slave |
i2c_data_p->operating_state = I2C_SEND_STOP; |
SSP2CON2bits.ACKDT = 1; // NACK |
SSP2CON2bits.ACKEN = 1; |
} |
break; |
case I2C_REQ_DATA: |
// Set module to receive one byte of data |
i2c_data_p->operating_state = I2C_RCV_DATA; |
SSP2CON2bits.RCEN = 1; |
break; |
case I2C_SEND_STOP: |
// Send the stop bit |
i2c_data_p->operating_state = I2C_IDLE; |
SSP2CON2bits.PEN = 1; |
i2c_data_p->master_status = I2C_MASTER_IDLE; |
i2c_data_p->return_status = I2C_RECV_OK; |
break; |
} |
} |
} |
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void I2C2_Interrupt_Slave() { |
uint8_t received_data; |
uint8_t data_read_from_buffer = 0; |
uint8_t data_written_to_buffer = 0; |
uint8_t overrun_error = 0; |
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// Clear SSP2OV (overflow bit) |
if (SSP2CON1bits.SSPOV == 1) { |
SSP2CON1bits.SSPOV = 0; |
// We failed to read the buffer in time, so we know we |
// can't properly receive this message, just put us in the |
// a state where we are looking for a new message |
i2c_data_p->operating_state = I2C_IDLE; |
overrun_error = 1; |
i2c_data_p->return_status = I2C_ERR_OVERRUN; |
} |
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// Read SPPxBUF if it is full |
if (SSP2STATbits.BF == 1) { |
received_data = SSP2BUF; |
// DBG_PRINT_I2C("I2C: data read from buffer: %x\r\n", SSP2BUF); |
data_read_from_buffer = 1; |
} |
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if (!overrun_error) { |
switch (i2c_data_p->operating_state) { |
case I2C_IDLE: |
{ |
// Ignore anything except a start |
if (SSP2STATbits.S == 1) { |
i2c_data_p->buffer_in_len_tmp = 0; |
i2c_data_p->operating_state = I2C_STARTED; |
} |
break; |
} |
case I2C_STARTED: |
{ |
// In this case, we expect either an address or a stop bit |
if (SSP2STATbits.P == 1) { |
// Return to idle mode |
i2c_data_p->operating_state = I2C_IDLE; |
} else if (data_read_from_buffer) { |
if (SSP2STATbits.D_nA == 0) { |
// Address received |
if (SSP2STATbits.R_nW == 0) { |
// Slave write mode |
i2c_data_p->operating_state = I2C_RCV_DATA; |
} else { |
// Slave read mode |
i2c_data_p->operating_state = I2C_SEND_DATA; |
// Process the first byte immediatly if sending data |
goto send; |
} |
} else { |
i2c_data_p->operating_state = I2C_IDLE; |
i2c_data_p->return_status = I2C_ERR_NODATA; |
} |
} |
break; |
} |
send: |
case I2C_SEND_DATA: |
{ |
if (!i2c_data_p->slave_sending_data) { |
// If we are not currently sending data, figure out what to reply with |
if (I2C2_Process_Receive(i2c_data_p->slave_in_last_byte)) { |
// Data exists to be returned, send first byte |
SSP2BUF = i2c_data_p->buffer_out[0]; |
i2c_data_p->buffer_out_ind = 1; |
i2c_data_p->slave_sending_data = 1; |
data_written_to_buffer = 1; |
} else { |
// Unknown request |
i2c_data_p->slave_sending_data = 0; |
i2c_data_p->operating_state = I2C_IDLE; |
} |
} else { |
// Sending remaining data back to master |
if (i2c_data_p->buffer_out_ind < i2c_data_p->buffer_out_len) { |
SSP2BUF = i2c_data_p->buffer_out[i2c_data_p->buffer_out_ind]; |
i2c_data_p->buffer_out_ind++; |
data_written_to_buffer = 1; |
} else { |
// Nothing left to send |
i2c_data_p->slave_sending_data = 0; |
i2c_data_p->operating_state = I2C_IDLE; |
} |
} |
break; |
} |
case I2C_RCV_DATA: |
{ |
// We expect either data or a stop bit or a (if a restart, an addr) |
if (SSP2STATbits.P == 1) { |
// Stop bit detected, we need to check to see if we also read data |
if (data_read_from_buffer) { |
if (SSP2STATbits.D_nA == 1) { |
// Data received with stop bit |
// TODO: Handle I2C buffer overflow |
i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = received_data; |
if (i2c_data_p->buffer_in_write_ind == MAXI2C2BUF-1) { |
i2c_data_p->buffer_in_write_ind = 0; |
} else { |
i2c_data_p->buffer_in_write_ind++; |
} |
i2c_data_p->buffer_in_len_tmp++; |
// Save the last byte received |
i2c_data_p->slave_in_last_byte = received_data; |
i2c_data_p->return_status = I2C_DATA_AVAL; |
} else { |
i2c_data_p->operating_state = I2C_IDLE; |
i2c_data_p->return_status = I2C_ERR_NODATA; |
} |
} |
i2c_data_p->buffer_in_len += i2c_data_p->buffer_in_len_tmp; |
i2c_data_p->operating_state = I2C_IDLE; |
} else if (data_read_from_buffer) { |
if (SSP2STATbits.D_nA == 1) { |
// Data received |
i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = received_data; |
if (i2c_data_p->buffer_in_write_ind == MAXI2C2BUF-1) { |
i2c_data_p->buffer_in_write_ind = 0; |
} else { |
i2c_data_p->buffer_in_write_ind++; |
} |
i2c_data_p->buffer_in_len_tmp++; |
// Save the last byte received |
i2c_data_p->slave_in_last_byte = received_data; |
i2c_data_p->return_status = I2C_DATA_AVAL; |
} else { |
// Restart bit detected |
if (SSP2STATbits.R_nW == 1) { |
i2c_data_p->buffer_in_len += i2c_data_p->buffer_in_len_tmp; |
i2c_data_p->operating_state = I2C_SEND_DATA; |
// Process the first byte immediatly if sending data |
goto send; |
} else { |
// Bad to recv an address again, we aren't ready |
i2c_data_p->operating_state = I2C_IDLE; |
i2c_data_p->return_status = I2C_ERR_NODATA; |
} |
} |
} |
break; |
} |
} |
} |
|
// Release the clock stretching bit (if we should) |
if (data_read_from_buffer || data_written_to_buffer) { |
// Release the clock |
if (SSP2CON1bits.CKP == 0) { |
SSP2CON1bits.CKP = 1; |
} |
} |
} |
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/* Returns 0 if I2C module is currently busy, otherwise returns status code */ |
uint8_t I2C2_Get_Status() { |
if (i2c_data_p->operating_mode == I2C_MODE_MASTER) { |
if (i2c_data_p->master_status != I2C_MASTER_IDLE || i2c_data_p->buffer_in_len == 0) { |
return 0; |
} else { |
return i2c_data_p->return_status; |
} |
} else { |
if (i2c_data_p->operating_state != I2C_IDLE || i2c_data_p->buffer_in_len == 0) { |
return 0; |
} else { |
return i2c_data_p->return_status; |
} |
} |
} |
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uint8_t I2C2_Buffer_Len() { |
return i2c_data_p->buffer_in_len; |
} |
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/* Returns 0 if I2C module is currently busy, otherwise returns buffer length */ |
uint8_t I2C2_Read_Buffer(uint8_t *buffer) { |
uint8_t i = 0; |
while (i2c_data_p->buffer_in_len != 0) { |
buffer[i] = i2c_data_p->buffer_in[i2c_data_p->buffer_in_read_ind]; |
i++; |
if (i2c_data_p->buffer_in_read_ind == MAXI2C2BUF-1) { |
i2c_data_p->buffer_in_read_ind = 0; |
} else { |
i2c_data_p->buffer_in_read_ind++; |
} |
i2c_data_p->buffer_in_len--; |
} |
return i; |
} |
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/* Put data to be returned here */ |
uint8_t I2C2_Process_Receive(uint8_t c) { |
uint8_t ret = 0; |
|
return ret; |
} |