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Kevin |
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#include <xc.h>
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#include "main.h"
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#include "I2C.h"
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static I2C_DATA *data_ptr;
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// Set up the data structures for the base_I2C.code
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// Should be called once before any i2c routines are called
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void I2C_Init(I2C_DATA *data) {
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data_ptr = data;
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I2C_CLK_TRIS = 1;
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I2C_DAT_TRIS = 1;
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data_ptr->buffer_in_len = 0;
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data_ptr->buffer_in_len_tmp = 0;
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data_ptr->buffer_in_read_ind = 0;
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data_ptr->buffer_in_write_ind = 0;
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data_ptr->buffer_out_ind = 0;
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data_ptr->buffer_out_len = 0;
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data_ptr->operating_mode = 0;
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data_ptr->operating_state = I2C_IDLE;
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data_ptr->return_status = 0;
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data_ptr->slave_in_last_byte = 0;
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data_ptr->slave_sending_data = 0;
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data_ptr->master_dest_addr = 0;
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data_ptr->master_status = I2C_MASTER_IDLE;
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// Enable I2C interrupt
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PIE1bits.SSP1IE = 1;
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}
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// Setup the PIC to operate as a master.
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void I2C_Configure_Master(char speed) {
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data_ptr->operating_mode = I2C_MODE_MASTER;
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SSP1STAT = 0x0;
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SSP1CON1 = 0x0;
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SSP1CON2 = 0x0;
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SSP1CON3 = 0x0;
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SSP1CON1bits.SSPM = 0x8; // I2C Master Mode
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if (speed) {
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SSP1ADD = 0x4F; // Operate at 100KHz (32MHz)
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} else {
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SSP1ADD = 0x13; // Operate at 400KHz (32MHz)
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}
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SSP1STATbits.SMP = 1; // Disable Slew Rate Control
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SSP1CON3bits.PCIE = 1; // Stop condition interrupt enable
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SSP1CON3bits.SCIE = 1; // Start condition interrupt enable
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SSP1CON1bits.SSPEN = 1; // Enable MSSP Module
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}
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// Sends length number of bytes in msg to specified address (no R/W bit)
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void I2C_Master_Send(char address, char length, char *msg) {
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char i;
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if (length == 0)
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return;
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// Copy message to send into buffer and save length/address
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for (i = 0; i < length; i++) {
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data_ptr->buffer_in[i] = msg[i];
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}
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data_ptr->buffer_in_len = length;
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data_ptr->master_dest_addr = address;
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data_ptr->buffer_in_read_ind = 0;
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data_ptr->buffer_in_write_ind = 0;
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// Change status to 'next' operation
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data_ptr->operating_state = I2C_SEND_ADDR;
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data_ptr->master_status = I2C_MASTER_SEND;
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// Generate start condition
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SSP1CON2bits.SEN = 1;
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}
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// Reads length number of bytes from address (no R/W bit)
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void I2C_Master_Recv(char address, char length) {
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if (length == 0)
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return;
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// Save length and address to get data from
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data_ptr->buffer_in_len = length;
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data_ptr->master_dest_addr = address;
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data_ptr->buffer_in_read_ind = 0;
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data_ptr->buffer_in_write_ind = 0;
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// Change status to 'next' operation
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data_ptr->operating_state = I2C_SEND_ADDR;
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data_ptr->master_status = I2C_MASTER_RECV;
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// Generate start condition
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SSP1CON2bits.SEN = 1;
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}
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// Writes msg to address then reads length number of bytes from address
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void I2C_Master_Restart(char address, char msg, char length) {
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char c;
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if (length == 0) {
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c = msg;
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I2C_Master_Send(address, 1, &c);
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return;
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}
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// Save length and address to get data from
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data_ptr->buffer_in[0] = msg;
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data_ptr->buffer_in_len = length;
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data_ptr->master_dest_addr = address;
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data_ptr->buffer_in_read_ind = 0;
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data_ptr->buffer_in_write_ind = 0;
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// Change status to 'next' operation
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data_ptr->operating_state = I2C_SEND_ADDR;
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data_ptr->master_status = I2C_MASTER_RESTART;
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// Generate start condition
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SSP1CON2bits.SEN = 1;
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}
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// Setup the PIC to operate as a slave. The address must not include the R/W bit
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void I2C_Configure_Slave(char addr) {
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data_ptr->operating_mode = I2C_MODE_SLAVE;
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SSP1ADD = addr << 1; // Set the slave address
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SSP1STAT = 0x0;
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SSP1CON1 = 0x0;
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SSP1CON2 = 0x0;
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SSP1CON3 = 0x0;
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SSP1CON1bits.SSPM = 0xE; // Enable Slave 7-bit w/ start/stop interrupts
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SSP1STATbits.SMP = 1; // Slew Off
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SSP1CON2bits.SEN = 1; // Enable clock-stretching
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SSP1CON1bits.SSPEN = 1; // Enable MSSP Module
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}
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void I2C_Interrupt_Handler() {
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// Call interrupt depending on which mode we are operating in
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if (data_ptr->operating_mode == I2C_MODE_MASTER) {
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I2C_Interrupt_Master();
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} else if (data_ptr->operating_mode == I2C_MODE_SLAVE) {
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I2C_Interrupt_Slave();
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}
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}
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// An internal subroutine used in the master version of the i2c_interrupt_handler
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void I2C_Interrupt_Master() {
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// If we are in the middle of sending data
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if (data_ptr->master_status == I2C_MASTER_SEND) {
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switch (data_ptr->operating_state) {
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case I2C_IDLE:
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break;
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case I2C_SEND_ADDR:
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// Send the address with read bit set
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data_ptr->operating_state = I2C_CHECK_ACK_SEND;
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SSP1BUF = (data_ptr->master_dest_addr << 1) | 0x0;
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break;
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case I2C_CHECK_ACK_SEND:
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// Check if ACK is received or not
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if (!SSP1CON2bits.ACKSTAT) {
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// If an ACK is received, send next byte of data
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if (data_ptr->buffer_in_read_ind < data_ptr->buffer_in_len) {
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SSP1BUF = data_ptr->buffer_in[data_ptr->buffer_in_read_ind];
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data_ptr->buffer_in_read_ind++;
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} else {
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// If no more data is to be sent, send stop bit
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data_ptr->operating_state = I2C_IDLE;
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SSP1CON2bits.PEN = 1;
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data_ptr->master_status = I2C_MASTER_IDLE;
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data_ptr->return_status = I2C_SEND_OK;
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}
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} else {
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// If a NACK is received, stop transmission and send error
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data_ptr->operating_state = I2C_IDLE;
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SSP1CON2bits.PEN = 1;
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data_ptr->master_status = I2C_MASTER_IDLE;
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data_ptr->return_status = I2C_SEND_FAIL;
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}
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break;
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}
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// If we are in the middle of receiving data
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} else if (data_ptr->master_status == I2C_MASTER_RECV) {
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switch (data_ptr->operating_state) {
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case I2C_IDLE:
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break;
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case I2C_SEND_ADDR:
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// Send address with write bit set
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data_ptr->operating_state = I2C_CHECK_ACK_RECV;
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SSP1BUF = (data_ptr->master_dest_addr << 1) | 0x1;
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break;
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case I2C_CHECK_ACK_RECV:
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// Check if ACK is received
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if (!SSP1CON2bits.ACKSTAT) {
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// If an ACK is received, set module to receive 1 byte of data
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data_ptr->operating_state = I2C_RCV_DATA;
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SSP1CON2bits.RCEN = 1;
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} else {
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// If a NACK is received, stop transmission and send error
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data_ptr->operating_state = I2C_IDLE;
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SSP1CON2bits.PEN = 1;
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data_ptr->master_status = I2C_MASTER_IDLE;
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data_ptr->return_status = I2C_RECV_FAIL;
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}
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break;
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case I2C_RCV_DATA:
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// On receive, save byte into buffer
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// TODO: Handle I2C buffer overflow
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data_ptr->buffer_in[data_ptr->buffer_in_write_ind] = SSP1BUF;
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data_ptr->buffer_in_write_ind++;
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if (data_ptr->buffer_in_write_ind < data_ptr->buffer_in_len) {
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// If we still need to read, send an ACK to the slave
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data_ptr->operating_state = I2C_REQ_DATA;
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SSP1CON2bits.ACKDT = 0; // ACK
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SSP1CON2bits.ACKEN = 1;
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} else {
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// If we are done reading, send an NACK to the slave
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data_ptr->operating_state = I2C_SEND_STOP;
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SSP1CON2bits.ACKDT = 1; // NACK
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SSP1CON2bits.ACKEN = 1;
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}
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break;
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case I2C_REQ_DATA:
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// Set module to receive one byte of data
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data_ptr->operating_state = I2C_RCV_DATA;
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SSP1CON2bits.RCEN = 1;
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break;
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case I2C_SEND_STOP:
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// Send the stop bit and copy message to send to Main()
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data_ptr->operating_state = I2C_IDLE;
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SSP1CON2bits.PEN = 1;
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data_ptr->master_status = I2C_MASTER_IDLE;
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data_ptr->return_status = I2C_RECV_OK;
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break;
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}
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} else if (data_ptr->master_status == I2C_MASTER_RESTART) {
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switch (data_ptr->operating_state) {
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case I2C_IDLE:
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break;
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case I2C_SEND_ADDR:
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// Send the address with read bit set
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data_ptr->operating_state = I2C_CHECK_ACK_SEND;
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SSP1BUF = (data_ptr->master_dest_addr << 1) | 0x0;
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break;
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case I2C_CHECK_ACK_SEND:
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// Check if ACK is received or not
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if (!SSP1CON2bits.ACKSTAT) {
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// If an ACK is received, send first byte of data
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SSP1BUF = data_ptr->buffer_in[0];
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data_ptr->operating_state = I2C_CHECK_ACK_RESTART;
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} else {
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// If a NACK is received, stop transmission and send error
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data_ptr->operating_state = I2C_IDLE;
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SSP1CON2bits.PEN = 1;
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data_ptr->master_status = I2C_MASTER_IDLE;
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data_ptr->return_status = I2C_SEND_FAIL;
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}
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break;
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case I2C_CHECK_ACK_RESTART:
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if (!SSP1CON2bits.ACKSTAT) {
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SSP1CON2bits.RSEN = 1;
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data_ptr->operating_state = I2C_SEND_ADDR_2;
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} else {
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// If a NACK is received, stop transmission and send error
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data_ptr->operating_state = I2C_IDLE;
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SSP1CON2bits.PEN = 1;
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data_ptr->master_status = I2C_MASTER_IDLE;
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data_ptr->return_status = I2C_SEND_FAIL;
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}
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break;
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case I2C_SEND_ADDR_2:
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// Send the address with read bit set
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data_ptr->operating_state = I2C_CHECK_ACK_RECV;
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SSP1BUF = (data_ptr->master_dest_addr << 1) | 0x1;
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break;
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case I2C_CHECK_ACK_RECV:
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// Check if ACK is received
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279 |
if (!SSP1CON2bits.ACKSTAT) {
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280 |
// If an ACK is received, set module to receive 1 byte of data
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281 |
data_ptr->operating_state = I2C_RCV_DATA;
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282 |
SSP1CON2bits.RCEN = 1;
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283 |
} else {
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284 |
// If a NACK is received, stop transmission and send error
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285 |
data_ptr->operating_state = I2C_IDLE;
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SSP1CON2bits.PEN = 1;
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287 |
data_ptr->master_status = I2C_MASTER_IDLE;
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288 |
data_ptr->return_status = I2C_RECV_FAIL;
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289 |
}
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290 |
break;
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case I2C_RCV_DATA:
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292 |
// On receive, save byte into buffer
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293 |
// TODO: Handle I2C buffer overflow
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294 |
data_ptr->buffer_in[data_ptr->buffer_in_write_ind] = SSP1BUF;
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295 |
data_ptr->buffer_in_write_ind++;
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296 |
if (data_ptr->buffer_in_write_ind < data_ptr->buffer_in_len) {
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297 |
// If we still need to read, send an ACK to the slave
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298 |
data_ptr->operating_state = I2C_REQ_DATA;
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299 |
SSP1CON2bits.ACKDT = 0; // ACK
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300 |
SSP1CON2bits.ACKEN = 1;
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301 |
} else {
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302 |
// If we are done reading, send an NACK to the slave
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303 |
data_ptr->operating_state = I2C_SEND_STOP;
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304 |
SSP1CON2bits.ACKDT = 1; // NACK
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305 |
SSP1CON2bits.ACKEN = 1;
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306 |
}
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307 |
break;
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308 |
case I2C_REQ_DATA:
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309 |
// Set module to receive one byte of data
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310 |
data_ptr->operating_state = I2C_RCV_DATA;
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311 |
SSP1CON2bits.RCEN = 1;
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312 |
break;
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313 |
case I2C_SEND_STOP:
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314 |
// Send the stop bit and copy message to send to Main()
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315 |
data_ptr->operating_state = I2C_IDLE;
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316 |
SSP1CON2bits.PEN = 1;
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317 |
data_ptr->master_status = I2C_MASTER_IDLE;
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318 |
data_ptr->return_status = I2C_RECV_OK;
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319 |
break;
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320 |
}
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321 |
}
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322 |
}
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323 |
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|
|
324 |
void I2C_Interrupt_Slave() {
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|
325 |
char received_data;
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|
326 |
char data_read_from_buffer = 0;
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|
327 |
char data_written_to_buffer = 0;
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|
328 |
char overrun_error = 0;
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|
329 |
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|
330 |
// Clear SSPOV (overflow bit)
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|
331 |
if (SSP1CON1bits.SSPOV == 1) {
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|
332 |
SSP1CON1bits.SSPOV = 0;
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|
333 |
// We failed to read the buffer in time, so we know we
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|
334 |
// can't properly receive this message, just put us in the
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|
335 |
// a state where we are looking for a new message
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|
336 |
data_ptr->operating_state = I2C_IDLE;
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|
337 |
overrun_error = 1;
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|
338 |
data_ptr->return_status = I2C_ERR_OVERRUN;
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|
339 |
}
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|
340 |
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|
341 |
// Read SPPxBUF if it is full
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|
342 |
if (SSP1STATbits.BF == 1) {
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|
343 |
received_data = SSP1BUF;
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|
344 |
data_read_from_buffer = 1;
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|
345 |
}
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|
346 |
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|
347 |
if (!overrun_error) {
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|
348 |
switch (data_ptr->operating_state) {
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|
349 |
case I2C_IDLE:
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|
350 |
{
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|
351 |
// Ignore anything except a start
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|
352 |
if (SSP1STATbits.S == 1) {
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|
353 |
data_ptr->buffer_in_len_tmp = 0;
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|
354 |
data_ptr->operating_state = I2C_STARTED;
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|
355 |
// if (data_read_from_buffer) {
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|
356 |
// if (SSPSTATbits.D_A == 1) {
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|
357 |
// DBG_PRINT_I2C("I2C Start: (ERROR) no address recieved\r\n");
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|
358 |
// // This is bad because we got data and we wanted an address
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|
359 |
// data_ptr->operating_state = I2C_IDLE;
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|
360 |
// data_ptr->return_status = I2C_ERR_NOADDR;
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|
361 |
// } else {
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|
362 |
// // Determine if we are sending or receiving data
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|
363 |
// if (SSPSTATbits.R_W == 1) {
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|
364 |
// data_ptr->operating_state = I2C_SEND_DATA;
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|
365 |
// } else {
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|
366 |
// data_ptr->operating_state = I2C_RCV_DATA;
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|
367 |
// }
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|
368 |
// }
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|
369 |
// } else {
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|
370 |
// data_ptr->operating_state = I2C_STARTED;
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|
371 |
// }
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|
372 |
}
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|
373 |
break;
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|
374 |
}
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|
375 |
case I2C_STARTED:
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|
376 |
{
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|
377 |
// In this case, we expect either an address or a stop bit
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|
378 |
if (SSP1STATbits.P == 1) {
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|
379 |
// Return to idle mode
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|
380 |
data_ptr->operating_state = I2C_IDLE;
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|
381 |
} else if (data_read_from_buffer) {
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|
382 |
if (SSP1STATbits.D_nA == 0) {
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|
383 |
// Address received
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|
384 |
if (SSP1STATbits.R_nW == 0) {
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|
385 |
// Slave write mode
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|
386 |
data_ptr->operating_state = I2C_RCV_DATA;
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|
|
387 |
} else {
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|
388 |
// Slave read mode
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|
389 |
data_ptr->operating_state = I2C_SEND_DATA;
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|
390 |
// Process the first byte immediatly if sending data
|
|
|
391 |
goto send;
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|
|
392 |
}
|
|
|
393 |
} else {
|
|
|
394 |
data_ptr->operating_state = I2C_IDLE;
|
|
|
395 |
data_ptr->return_status = I2C_ERR_NODATA;
|
|
|
396 |
}
|
|
|
397 |
}
|
|
|
398 |
break;
|
|
|
399 |
}
|
|
|
400 |
send:
|
|
|
401 |
case I2C_SEND_DATA:
|
|
|
402 |
{
|
|
|
403 |
if (!data_ptr->slave_sending_data) {
|
|
|
404 |
// If we are not currently sending data, figure out what to reply with
|
|
|
405 |
if (I2C_Process_Send(data_ptr->slave_in_last_byte)) {
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|
|
406 |
// Data exists to be returned, send first byte
|
|
|
407 |
SSP1BUF = data_ptr->buffer_out[0];
|
|
|
408 |
data_ptr->buffer_out_ind = 1;
|
|
|
409 |
data_ptr->slave_sending_data = 1;
|
|
|
410 |
data_written_to_buffer = 1;
|
|
|
411 |
} else {
|
|
|
412 |
// Unknown request
|
|
|
413 |
data_ptr->slave_sending_data = 0;
|
|
|
414 |
data_ptr->operating_state = I2C_IDLE;
|
|
|
415 |
}
|
|
|
416 |
} else {
|
|
|
417 |
// Sending remaining data back to master
|
|
|
418 |
if (data_ptr->buffer_out_ind < data_ptr->buffer_out_len) {
|
|
|
419 |
SSP1BUF = data_ptr->buffer_out[data_ptr->buffer_out_ind];
|
|
|
420 |
data_ptr->buffer_out_ind++;
|
|
|
421 |
data_written_to_buffer = 1;
|
|
|
422 |
} else {
|
|
|
423 |
// Nothing left to send
|
|
|
424 |
data_ptr->slave_sending_data = 0;
|
|
|
425 |
data_ptr->operating_state = I2C_IDLE;
|
|
|
426 |
}
|
|
|
427 |
}
|
|
|
428 |
break;
|
|
|
429 |
}
|
|
|
430 |
case I2C_RCV_DATA:
|
|
|
431 |
{
|
|
|
432 |
// We expect either data or a stop bit or a (if a restart, an addr)
|
|
|
433 |
if (SSP1STATbits.P == 1) {
|
|
|
434 |
// Stop bit detected, we need to check to see if we also read data
|
|
|
435 |
if (data_read_from_buffer) {
|
|
|
436 |
if (SSP1STATbits.D_nA == 1) {
|
|
|
437 |
// Data received with stop bit
|
|
|
438 |
// TODO: Handle I2C buffer overflow
|
|
|
439 |
data_ptr->buffer_in[data_ptr->buffer_in_write_ind] = received_data;
|
|
|
440 |
if (data_ptr->buffer_in_write_ind == I2C_BUFFER_SIZE-1) {
|
|
|
441 |
data_ptr->buffer_in_write_ind = 0;
|
|
|
442 |
} else {
|
|
|
443 |
data_ptr->buffer_in_write_ind++;
|
|
|
444 |
}
|
|
|
445 |
data_ptr->buffer_in_len_tmp++;
|
|
|
446 |
// Save the last byte received
|
|
|
447 |
data_ptr->slave_in_last_byte = received_data;
|
|
|
448 |
data_ptr->return_status = I2C_DATA_AVAL;
|
|
|
449 |
} else {
|
|
|
450 |
data_ptr->operating_state = I2C_IDLE;
|
|
|
451 |
data_ptr->return_status = I2C_ERR_NODATA;
|
|
|
452 |
}
|
|
|
453 |
}
|
|
|
454 |
data_ptr->buffer_in_len += data_ptr->buffer_in_len_tmp;
|
|
|
455 |
data_ptr->operating_state = I2C_IDLE;
|
|
|
456 |
} else if (data_read_from_buffer) {
|
|
|
457 |
if (SSP1STATbits.D_nA == 1) {
|
|
|
458 |
// Data received
|
|
|
459 |
data_ptr->buffer_in[data_ptr->buffer_in_write_ind] = received_data;
|
|
|
460 |
if (data_ptr->buffer_in_write_ind == I2C_BUFFER_SIZE-1) {
|
|
|
461 |
data_ptr->buffer_in_write_ind = 0;
|
|
|
462 |
} else {
|
|
|
463 |
data_ptr->buffer_in_write_ind++;
|
|
|
464 |
}
|
|
|
465 |
data_ptr->buffer_in_len_tmp++;
|
|
|
466 |
// Save the last byte received
|
|
|
467 |
data_ptr->slave_in_last_byte = received_data;
|
|
|
468 |
data_ptr->return_status = I2C_DATA_AVAL;
|
|
|
469 |
} else {
|
|
|
470 |
// Restart bit detected
|
|
|
471 |
if (SSP1STATbits.R_nW == 1) {
|
|
|
472 |
data_ptr->buffer_in_len += data_ptr->buffer_in_len_tmp;
|
|
|
473 |
data_ptr->operating_state = I2C_SEND_DATA;
|
|
|
474 |
// Process the first byte immediatly if sending data
|
|
|
475 |
goto send;
|
|
|
476 |
} else {
|
|
|
477 |
// Bad to recv an address again, we aren't ready
|
|
|
478 |
data_ptr->operating_state = I2C_IDLE;
|
|
|
479 |
data_ptr->return_status = I2C_ERR_NODATA;
|
|
|
480 |
}
|
|
|
481 |
}
|
|
|
482 |
}
|
|
|
483 |
break;
|
|
|
484 |
}
|
|
|
485 |
}
|
|
|
486 |
}
|
|
|
487 |
|
|
|
488 |
// Release the clock stretching bit (if we should)
|
|
|
489 |
if (data_read_from_buffer || data_written_to_buffer) {
|
|
|
490 |
// Release the clock
|
|
|
491 |
if (SSP1CON1bits.CKP == 0) {
|
|
|
492 |
SSP1CON1bits.CKP = 1;
|
|
|
493 |
}
|
|
|
494 |
}
|
|
|
495 |
}
|
|
|
496 |
|
|
|
497 |
/* Returns 0 if I2C module is currently busy, otherwise returns status code */
|
|
|
498 |
char I2C_Get_Status() {
|
|
|
499 |
if (data_ptr->operating_mode == I2C_MODE_MASTER) {
|
|
|
500 |
if (data_ptr->master_status != I2C_MASTER_IDLE || data_ptr->buffer_in_len == 0) {
|
|
|
501 |
return 0;
|
|
|
502 |
} else {
|
|
|
503 |
return data_ptr->return_status;
|
|
|
504 |
}
|
|
|
505 |
} else {
|
|
|
506 |
if (data_ptr->operating_state != I2C_IDLE || data_ptr->buffer_in_len == 0) {
|
|
|
507 |
return 0;
|
|
|
508 |
} else {
|
|
|
509 |
return data_ptr->return_status;
|
|
|
510 |
}
|
|
|
511 |
}
|
|
|
512 |
}
|
|
|
513 |
|
|
|
514 |
char I2C_Buffer_Len() {
|
|
|
515 |
return data_ptr->buffer_in_len;
|
|
|
516 |
}
|
|
|
517 |
|
|
|
518 |
/* Returns 0 if I2C module is currently busy, otherwise returns buffer length */
|
|
|
519 |
char I2C_Read_Buffer(char *buffer) {
|
|
|
520 |
char i = 0;
|
|
|
521 |
while (data_ptr->buffer_in_len != 0) {
|
|
|
522 |
buffer[i] = data_ptr->buffer_in[data_ptr->buffer_in_read_ind];
|
|
|
523 |
i++;
|
|
|
524 |
if (data_ptr->buffer_in_read_ind == I2C_BUFFER_SIZE-1) {
|
|
|
525 |
data_ptr->buffer_in_read_ind = 0;
|
|
|
526 |
} else {
|
|
|
527 |
data_ptr->buffer_in_read_ind++;
|
|
|
528 |
}
|
|
|
529 |
data_ptr->buffer_in_len--;
|
|
|
530 |
}
|
|
|
531 |
return i;
|
|
|
532 |
}
|
|
|
533 |
|
|
|
534 |
/* Put data to be returned here */
|
|
|
535 |
char I2C_Process_Send(char c) {
|
|
|
536 |
char ret = 0;
|
|
|
537 |
switch (c) {
|
|
|
538 |
case 0xAA:
|
|
|
539 |
data_ptr->buffer_out[0] = 'A';
|
|
|
540 |
data_ptr->buffer_out_len = 1;
|
|
|
541 |
ret = 1;
|
|
|
542 |
break;
|
|
|
543 |
case 0xBB:
|
|
|
544 |
data_ptr->buffer_out[0] = '1';
|
|
|
545 |
data_ptr->buffer_out[1] = '2';
|
|
|
546 |
data_ptr->buffer_out_len = 2;
|
|
|
547 |
ret = 1;
|
|
|
548 |
break;
|
|
|
549 |
}
|
|
|
550 |
return ret;
|
|
|
551 |
}
|