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#include <xc.h>#include "main.h"#include "I2C.h"static I2C_DATA *data_ptr;// Set up the data structures for the base_I2C.code// Should be called once before any i2c routines are calledvoid I2C_Init(I2C_DATA *data) {data_ptr = data;I2C_CLK_TRIS = 1;I2C_DAT_TRIS = 1;data_ptr->buffer_in_len = 0;data_ptr->buffer_in_len_tmp = 0;data_ptr->buffer_in_read_ind = 0;data_ptr->buffer_in_write_ind = 0;data_ptr->buffer_out_ind = 0;data_ptr->buffer_out_len = 0;data_ptr->operating_mode = 0;data_ptr->operating_state = I2C_IDLE;data_ptr->return_status = 0;data_ptr->slave_in_last_byte = 0;data_ptr->slave_sending_data = 0;data_ptr->master_dest_addr = 0;data_ptr->master_status = I2C_MASTER_IDLE;// Enable I2C interruptPIE1bits.SSP1IE = 1;}// Setup the PIC to operate as a master.void I2C_Configure_Master(char speed) {data_ptr->operating_mode = I2C_MODE_MASTER;SSP1STAT = 0x0;SSP1CON1 = 0x0;SSP1CON2 = 0x0;SSP1CON3 = 0x0;SSP1CON1bits.SSPM = 0x8; // I2C Master Modeif (speed) {SSP1ADD = 0x4F; // Operate at 100KHz (32MHz)} else {SSP1ADD = 0x13; // Operate at 400KHz (32MHz)}SSP1STATbits.SMP = 1; // Disable Slew Rate ControlSSP1CON3bits.PCIE = 1; // Stop condition interrupt enableSSP1CON3bits.SCIE = 1; // Start condition interrupt enableSSP1CON1bits.SSPEN = 1; // Enable MSSP Module}// Sends length number of bytes in msg to specified address (no R/W bit)void I2C_Master_Send(char address, char *msg, char length) {char i;if (length == 0)return;// Copy message to send into buffer and save length/addressfor (i = 0; i < length; i++) {data_ptr->buffer_in[i] = msg[i];}data_ptr->buffer_in_len = length;data_ptr->master_dest_addr = address;data_ptr->buffer_in_read_ind = 0;data_ptr->buffer_in_write_ind = 0;// Change status to 'next' operationdata_ptr->operating_state = I2C_SEND_ADDR;data_ptr->master_status = I2C_MASTER_SEND;// Generate start conditionSSP1CON2bits.SEN = 1;}// Reads length number of bytes from address (no R/W bit)void I2C_Master_Recv(char address, char length) {if (length == 0)return;// Save length and address to get data fromdata_ptr->buffer_in_len = length;data_ptr->master_dest_addr = address;data_ptr->buffer_in_read_ind = 0;data_ptr->buffer_in_write_ind = 0;// Change status to 'next' operationdata_ptr->operating_state = I2C_SEND_ADDR;data_ptr->master_status = I2C_MASTER_RECV;// Generate start conditionSSP1CON2bits.SEN = 1;}// Writes msg to address then reads length number of bytes from addressvoid I2C_Master_Restart(char address, char msg, char length) {char c;if (length == 0) {c = msg;I2C_Master_Send(address, &c, 1);return;}// Save length and address to get data fromdata_ptr->buffer_in[0] = msg;data_ptr->buffer_in_len = length;data_ptr->master_dest_addr = address;data_ptr->buffer_in_read_ind = 0;data_ptr->buffer_in_write_ind = 0;// Change status to 'next' operationdata_ptr->operating_state = I2C_SEND_ADDR;data_ptr->master_status = I2C_MASTER_RESTART;// Generate start conditionSSP1CON2bits.SEN = 1;}// Setup the PIC to operate as a slave. The address must not include the R/W bitvoid I2C_Configure_Slave(char addr) {data_ptr->operating_mode = I2C_MODE_SLAVE;SSP1ADD = addr << 1; // Set the slave addressSSP1STAT = 0x0;SSP1CON1 = 0x0;SSP1CON2 = 0x0;SSP1CON3 = 0x0;SSP1CON1bits.SSPM = 0xE; // Enable Slave 7-bit w/ start/stop interruptsSSP1STATbits.SMP = 1; // Slew OffSSP1CON2bits.SEN = 1; // Enable clock-stretchingSSP1CON1bits.SSPEN = 1; // Enable MSSP Module}void I2C_Interrupt_Handler() {// Call interrupt depending on which mode we are operating inif (data_ptr->operating_mode == I2C_MODE_MASTER) {I2C_Interrupt_Master();} else if (data_ptr->operating_mode == I2C_MODE_SLAVE) {I2C_Interrupt_Slave();}}// An internal subroutine used in the master version of the i2c_interrupt_handlervoid I2C_Interrupt_Master() {// If we are in the middle of sending dataif (data_ptr->master_status == I2C_MASTER_SEND) {switch (data_ptr->operating_state) {case I2C_IDLE:break;case I2C_SEND_ADDR:// Send the address with read bit setdata_ptr->operating_state = I2C_CHECK_ACK_SEND;SSP1BUF = (data_ptr->master_dest_addr << 1) | 0x0;break;case I2C_CHECK_ACK_SEND:// Check if ACK is received or notif (!SSP1CON2bits.ACKSTAT) {// If an ACK is received, send next byte of dataif (data_ptr->buffer_in_read_ind < data_ptr->buffer_in_len) {SSP1BUF = data_ptr->buffer_in[data_ptr->buffer_in_read_ind];data_ptr->buffer_in_read_ind++;} else {// If no more data is to be sent, send stop bitdata_ptr->operating_state = I2C_IDLE;SSP1CON2bits.PEN = 1;data_ptr->master_status = I2C_MASTER_IDLE;data_ptr->return_status = I2C_SEND_OK;}} else {// If a NACK is received, stop transmission and send errordata_ptr->operating_state = I2C_IDLE;SSP1CON2bits.PEN = 1;data_ptr->master_status = I2C_MASTER_IDLE;data_ptr->return_status = I2C_SEND_FAIL;}break;}// If we are in the middle of receiving data} else if (data_ptr->master_status == I2C_MASTER_RECV) {switch (data_ptr->operating_state) {case I2C_IDLE:break;case I2C_SEND_ADDR:// Send address with write bit setdata_ptr->operating_state = I2C_CHECK_ACK_RECV;char tmp = (data_ptr->master_dest_addr << 1);tmp |= 0x1;SSP1BUF = tmp;break;case I2C_CHECK_ACK_RECV:// Check if ACK is receivedif (!SSP1CON2bits.ACKSTAT) {// If an ACK is received, set module to receive 1 byte of datadata_ptr->operating_state = I2C_RCV_DATA;SSP1CON2bits.RCEN = 1;} else {// If a NACK is received, stop transmission and send errordata_ptr->operating_state = I2C_IDLE;SSP1CON2bits.PEN = 1;data_ptr->master_status = I2C_MASTER_IDLE;data_ptr->return_status = I2C_RECV_FAIL;}break;case I2C_RCV_DATA:// On receive, save byte into buffer// TODO: Handle I2C buffer overflowdata_ptr->buffer_in[data_ptr->buffer_in_write_ind] = SSP1BUF;data_ptr->buffer_in_write_ind++;if (data_ptr->buffer_in_write_ind < data_ptr->buffer_in_len) {// If we still need to read, send an ACK to the slavedata_ptr->operating_state = I2C_REQ_DATA;SSP1CON2bits.ACKDT = 0; // ACKSSP1CON2bits.ACKEN = 1;} else {// If we are done reading, send an NACK to the slavedata_ptr->operating_state = I2C_SEND_STOP;SSP1CON2bits.ACKDT = 1; // NACKSSP1CON2bits.ACKEN = 1;}break;case I2C_REQ_DATA:// Set module to receive one byte of datadata_ptr->operating_state = I2C_RCV_DATA;SSP1CON2bits.RCEN = 1;break;case I2C_SEND_STOP:// Send the stop bit and copy message to send to Main()data_ptr->operating_state = I2C_IDLE;SSP1CON2bits.PEN = 1;data_ptr->master_status = I2C_MASTER_IDLE;data_ptr->return_status = I2C_RECV_OK;break;}} else if (data_ptr->master_status == I2C_MASTER_RESTART) {switch (data_ptr->operating_state) {case I2C_IDLE:break;case I2C_SEND_ADDR:// Send the address with write bit setdata_ptr->operating_state = I2C_CHECK_ACK_SEND;SSP1BUF = (data_ptr->master_dest_addr << 1) | 0x0;break;case I2C_CHECK_ACK_SEND:// Check if ACK is received or notif (!SSP1CON2bits.ACKSTAT) {// If an ACK is received, send first byte of dataSSP1BUF = data_ptr->buffer_in[0];data_ptr->operating_state = I2C_CHECK_ACK_RESTART;} else {// If a NACK is received, stop transmission and send errordata_ptr->operating_state = I2C_IDLE;SSP1CON2bits.PEN = 1;data_ptr->master_status = I2C_MASTER_IDLE;data_ptr->return_status = I2C_SEND_FAIL;}break;case I2C_CHECK_ACK_RESTART:if (!SSP1CON2bits.ACKSTAT) {SSP1CON2bits.RSEN = 1;data_ptr->operating_state = I2C_SEND_ADDR_2;} else {// If a NACK is received, stop transmission and send errordata_ptr->operating_state = I2C_IDLE;SSP1CON2bits.PEN = 1;data_ptr->master_status = I2C_MASTER_IDLE;data_ptr->return_status = I2C_SEND_FAIL;}break;case I2C_SEND_ADDR_2:// Send the address with read bit setdata_ptr->operating_state = I2C_CHECK_ACK_RECV;char tmp = (data_ptr->master_dest_addr << 1);tmp |= 0x1;SSP1BUF = tmp;break;case I2C_CHECK_ACK_RECV:// Check if ACK is receivedif (!SSP1CON2bits.ACKSTAT) {// If an ACK is received, set module to receive 1 byte of datadata_ptr->operating_state = I2C_RCV_DATA;SSP1CON2bits.RCEN = 1;} else {// If a NACK is received, stop transmission and send errordata_ptr->operating_state = I2C_IDLE;SSP1CON2bits.PEN = 1;data_ptr->master_status = I2C_MASTER_IDLE;data_ptr->return_status = I2C_RECV_FAIL;}break;case I2C_RCV_DATA:// On receive, save byte into buffer// TODO: Handle I2C buffer overflowdata_ptr->buffer_in[data_ptr->buffer_in_write_ind] = SSP1BUF;data_ptr->buffer_in_write_ind++;if (data_ptr->buffer_in_write_ind < data_ptr->buffer_in_len) {// If we still need to read, send an ACK to the slavedata_ptr->operating_state = I2C_REQ_DATA;SSP1CON2bits.ACKDT = 0; // ACKSSP1CON2bits.ACKEN = 1;} else {// If we are done reading, send an NACK to the slavedata_ptr->operating_state = I2C_SEND_STOP;SSP1CON2bits.ACKDT = 1; // NACKSSP1CON2bits.ACKEN = 1;}break;case I2C_REQ_DATA:// Set module to receive one byte of datadata_ptr->operating_state = I2C_RCV_DATA;SSP1CON2bits.RCEN = 1;break;case I2C_SEND_STOP:// Send the stop bit and copy message to send to Main()data_ptr->operating_state = I2C_IDLE;SSP1CON2bits.PEN = 1;data_ptr->master_status = I2C_MASTER_IDLE;data_ptr->return_status = I2C_RECV_OK;break;}}}void I2C_Interrupt_Slave() {char received_data;char data_read_from_buffer = 0;char data_written_to_buffer = 0;char overrun_error = 0;// Clear SSPOV (overflow bit)if (SSP1CON1bits.SSPOV == 1) {SSP1CON1bits.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 messagedata_ptr->operating_state = I2C_IDLE;overrun_error = 1;data_ptr->return_status = I2C_ERR_OVERRUN;}// Read SPPxBUF if it is fullif (SSP1STATbits.BF == 1) {received_data = SSP1BUF;data_read_from_buffer = 1;}if (!overrun_error) {switch (data_ptr->operating_state) {case I2C_IDLE:{// Ignore anything except a startif (SSP1STATbits.S == 1) {data_ptr->buffer_in_len_tmp = 0;data_ptr->operating_state = I2C_STARTED;// if (data_read_from_buffer) {// if (SSPSTATbits.D_A == 1) {// DBG_PRINT_I2C("I2C Start: (ERROR) no address recieved\r\n");// // This is bad because we got data and we wanted an address// data_ptr->operating_state = I2C_IDLE;// data_ptr->return_status = I2C_ERR_NOADDR;// } else {// // Determine if we are sending or receiving data// if (SSPSTATbits.R_W == 1) {// data_ptr->operating_state = I2C_SEND_DATA;// } else {// data_ptr->operating_state = I2C_RCV_DATA;// }// }// } else {// data_ptr->operating_state = I2C_STARTED;// }}break;}case I2C_STARTED:{// In this case, we expect either an address or a stop bitif (SSP1STATbits.P == 1) {// Return to idle modedata_ptr->operating_state = I2C_IDLE;} else if (data_read_from_buffer) {if (SSP1STATbits.D_nA == 0) {// Address receivedif (SSP1STATbits.R_nW == 0) {// Slave write modedata_ptr->operating_state = I2C_RCV_DATA;} else {// Slave read modedata_ptr->operating_state = I2C_SEND_DATA;// Process the first byte immediatly if sending datagoto send;}} else {data_ptr->operating_state = I2C_IDLE;data_ptr->return_status = I2C_ERR_NODATA;}}break;}send:case I2C_SEND_DATA:{if (!data_ptr->slave_sending_data) {// If we are not currently sending data, figure out what to reply withif (I2C_Process_Send(data_ptr->slave_in_last_byte)) {// Data exists to be returned, send first byteSSP1BUF = data_ptr->buffer_out[0];data_ptr->buffer_out_ind = 1;data_ptr->slave_sending_data = 1;data_written_to_buffer = 1;} else {// Unknown requestdata_ptr->slave_sending_data = 0;data_ptr->operating_state = I2C_IDLE;}} else {// Sending remaining data back to masterif (data_ptr->buffer_out_ind < data_ptr->buffer_out_len) {SSP1BUF = data_ptr->buffer_out[data_ptr->buffer_out_ind];data_ptr->buffer_out_ind++;data_written_to_buffer = 1;} else {// Nothing left to senddata_ptr->slave_sending_data = 0;data_ptr->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 (SSP1STATbits.P == 1) {// Stop bit detected, we need to check to see if we also read dataif (data_read_from_buffer) {if (SSP1STATbits.D_nA == 1) {// Data received with stop bit// TODO: Handle I2C buffer overflowdata_ptr->buffer_in[data_ptr->buffer_in_write_ind] = received_data;if (data_ptr->buffer_in_write_ind == I2C_BUFFER_SIZE-1) {data_ptr->buffer_in_write_ind = 0;} else {data_ptr->buffer_in_write_ind++;}data_ptr->buffer_in_len_tmp++;// Save the last byte receiveddata_ptr->slave_in_last_byte = received_data;data_ptr->return_status = I2C_DATA_AVAL;} else {data_ptr->operating_state = I2C_IDLE;data_ptr->return_status = I2C_ERR_NODATA;}}data_ptr->buffer_in_len += data_ptr->buffer_in_len_tmp;data_ptr->operating_state = I2C_IDLE;} else if (data_read_from_buffer) {if (SSP1STATbits.D_nA == 1) {// Data receiveddata_ptr->buffer_in[data_ptr->buffer_in_write_ind] = received_data;if (data_ptr->buffer_in_write_ind == I2C_BUFFER_SIZE-1) {data_ptr->buffer_in_write_ind = 0;} else {data_ptr->buffer_in_write_ind++;}data_ptr->buffer_in_len_tmp++;// Save the last byte receiveddata_ptr->slave_in_last_byte = received_data;data_ptr->return_status = I2C_DATA_AVAL;} else {// Restart bit detectedif (SSP1STATbits.R_nW == 1) {data_ptr->buffer_in_len += data_ptr->buffer_in_len_tmp;data_ptr->operating_state = I2C_SEND_DATA;// Process the first byte immediatly if sending datagoto send;} else {// Bad to recv an address again, we aren't readydata_ptr->operating_state = I2C_IDLE;data_ptr->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 clockif (SSP1CON1bits.CKP == 0) {SSP1CON1bits.CKP = 1;}}}/* Returns 0 if I2C module is currently busy, otherwise returns status code */char I2C_Get_Status() {if (data_ptr->operating_mode == I2C_MODE_MASTER) {if (data_ptr->master_status != I2C_MASTER_IDLE || data_ptr->buffer_in_len == 0) {return 0;} else {return data_ptr->return_status;}} else {if (data_ptr->operating_state != I2C_IDLE || data_ptr->buffer_in_len == 0) {return 0;} else {return data_ptr->return_status;}}}char I2C_Buffer_Len() {return data_ptr->buffer_in_len;}/* Returns 0 if I2C module is currently busy, otherwise returns buffer length */char I2C_Read_Buffer(char *buffer) {char i = 0;while (data_ptr->buffer_in_len != 0) {buffer[i] = data_ptr->buffer_in[data_ptr->buffer_in_read_ind];i++;if (data_ptr->buffer_in_read_ind == I2C_BUFFER_SIZE-1) {data_ptr->buffer_in_read_ind = 0;} else {data_ptr->buffer_in_read_ind++;}data_ptr->buffer_in_len--;}return i;}/* Put data to be returned here */char I2C_Process_Send(char c) {char ret = 0;switch (c) {case 0xAA:data_ptr->buffer_out[0] = 'A';data_ptr->buffer_out_len = 1;ret = 1;break;case 0xBB:data_ptr->buffer_out[0] = '1';data_ptr->buffer_out[1] = '2';data_ptr->buffer_out_len = 2;ret = 1;break;}return ret;}