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#include "defines.h"

#include "I2C1.h"

static I2C1_DATA *i2c_data_p;

// Initialize the data structures, should be called once before any I2C routines are called

void I2C1_Init(I2C1_DATA *data, uint8_t speed, uint8_t address) {

    i2c_data_p = data;

    i2c_data_p->buffer_in_len = 0;

    i2c_data_p->buffer_in_read_ind = 0;

    i2c_data_p->buffer_in_write_ind = 0;

    i2c_data_p->buffer_out_ind = 0;

    i2c_data_p->buffer_out_len = 0;

    i2c_data_p->operating_state = I2C1_IDLE;

    i2c_data_p->return_status = 0;

    i2c_data_p->slave_in_last_byte = 0;

    i2c_data_p->slave_sending_data = 0;

    i2c_data_p->master_dest_addr = 0;

    i2c_data_p->master_status = I2C1_MASTER_IDLE;

    INTDisableInterrupts();

    // Enable the I2C module and set the clock stretch enable bit

    // Note: Automatically overrides any other pin settings

    I2C1CONSET = 0x00008040;

    I2C1ADD = address;

    if (!speed) I2C1BRG = 0x05A;    // Operate at 400kHZ (80MHz)

    else        I2C1BRG = 0x186;    // Operate at 100kHZ (80MHz)

    IFS0CLR = 0xE0000000;   // Clear any existing events

    IPC6CLR = 0x00001F00;   // Reset priority levels

    IPC6SET = 0x00001500;   // Set IPL=5, Subpriority 1

    IEC0SET = 0xE0000000;   // Enable I2C1 interrupts

    INTEnableInterrupts();

}

// Sends length number of bytes in msg to specified address (no R/W bit)

// Will return status I2C1_SEND_OK or I2C1_SEND_FAIL

void I2C1_Master_Send(uint8_t address, uint8_t *msg, uint32_t length) {

    uint32_t i;

    if (length == 0)

        return;

    // 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;

    // Change status to 'next' operation

    i2c_data_p->operating_state = I2C1_SEND_ADDR;

    i2c_data_p->master_status = I2C1_MASTER_SEND;

    // Generate start condition

    I2C1CONbits.SEN = 1;

}

// Reads length number of bytes from address (no R/W bit)

// Will return status I2C1_RECV_OK or I2C1_RECV_FAIL

void I2C1_Master_Recv(uint8_t address, uint32_t length) {

    if (length == 0)

        return;

    // 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;

    // Change status to 'next' operation

    i2c_data_p->operating_state = I2C1_SEND_ADDR;

    i2c_data_p->master_status = I2C1_MASTER_RECV;

    // Generate start condition

    I2C1CONbits.SEN = 1;

}

// Writes msg to address then reads length number of bytes from address

// Will return status I2C1_SEND_FAIL or I2C1_RECV_FAIL or I2C1_RECV_OK

void I2C1_Master_Restart(uint8_t address, uint8_t msg, uint32_t length) {

    uint8_t c;

    if (length == 0) {

        c = msg;

        I2C1_Master_Send(address, &c, 1);

        return;

    }

    // 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;

    // Change status to 'next' operation

    i2c_data_p->operating_state = I2C1_SEND_ADDR;

    i2c_data_p->master_status = I2C1_MASTER_RESTART;

    // Generate start condition

    I2C1CONbits.SEN = 1;

}

void __ISR(_I2C_1_VECTOR, ipl5) __I2C_1_Interrupt_Handler(void) {

    // Bus collision event

    if (IFS0bits.I2C1BIF) {

        // TODO: Handle bus collision events here

        IFS0CLR = 0x20000000;

    }

    // Slave event

    if (IFS0bits.I2C1SIF) {

        I2C1_Interrupt_Slave();

        IFS0CLR = 0x40000000;

    }

    // Master event

    if (IFS0bits.I2C1MIF) {

        I2C1_Interrupt_Master();

        IFS0CLR = 0x80000000;

    }

}

// An internal subroutine used in the master version of the i2c_interrupt_handler

void I2C1_Interrupt_Master() {

    /* The PIC32 family has different master interrupts than the PIC8 family

     * Master mode operations that generate a slave interrupt are:

     * 1. Start condition

     * 2. Repeated start sequence

     * 3. Stop condition

     * 4. Data transfer byte received

     * 5. During a send ACK or NACK sequence to slave

     * 6. Data transfer byte transmitted

     * 7. During a slave-detected stop

     */

    if (I2C1STATbits.IWCOL == 1) {

        // TODO: Handle write collisions

        I2C1STATbits.IWCOL = 0;

    }

    // If we are in the middle of sending data

    if (i2c_data_p->master_status == I2C1_MASTER_SEND) {

        switch (i2c_data_p->operating_state) {

            case I2C1_IDLE:

                break;

            case I2C1_SEND_ADDR:

                // Send the address with read bit set

                i2c_data_p->operating_state = I2C1_CHECK_ACK_SEND;

                I2C1TRN = (i2c_data_p->master_dest_addr << 1) | 0x0;

                break;

            case I2C1_CHECK_ACK_SEND:

                // Check if ACK is received or not

                if (!I2C1STATbits.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) {

                        I2C1TRN = 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 = I2C1_STOPPED;

                        I2C1CONbits.PEN = 1;

                        i2c_data_p->return_status = I2C1_SEND_OK;

                    }

                } else {

                    // If a NACK is received, stop transmission and send error

                    i2c_data_p->operating_state = I2C1_STOPPED;

                    I2C1CONbits.PEN = 1;

                    i2c_data_p->return_status = I2C1_SEND_FAIL;

                }

                break;

            case I2C1_STOPPED:

                i2c_data_p->operating_state = I2C1_IDLE;

                i2c_data_p->master_status = I2C1_MASTER_IDLE;

                break;

        }

    // If we are in the middle of receiving data

    } else if (i2c_data_p->master_status == I2C1_MASTER_RECV) {

        switch (i2c_data_p->operating_state) {

            case I2C1_IDLE:

                break;

            case I2C1_SEND_ADDR:

                // Send address with write bit set

                i2c_data_p->operating_state = I2C1_CHECK_ACK_RECV;

                I2C1TRN = (i2c_data_p->master_dest_addr << 1) | 0x1;

                break;

            case I2C1_CHECK_ACK_RECV:

                // Check if ACK is received

                if (!I2C1STATbits.ACKSTAT) {

                    // If an ACK is received, set module to receive 1 byte of data

                    i2c_data_p->operating_state = I2C1_RCV_DATA;

                    I2C1CONbits.RCEN = 1;

                } else {

                    // If a NACK is received, stop transmission and send error

                    i2c_data_p->operating_state = I2C1_STOPPED;

                    I2C1CONbits.PEN = 1;

                    i2c_data_p->return_status = I2C1_RECV_FAIL;

                }

                break;

            case I2C1_RCV_DATA:

                // On receive, save byte into buffer

                // TODO: Handle possible I2C buffer overflow

                i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = I2C1RCV;

                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 = I2C1_REQ_DATA;

                    I2C1CONbits.ACKDT = 0;  // ACK

                    I2C1CONbits.ACKEN = 1;

                } else {

                    // If we are done reading, send an NACK to the slave

                    i2c_data_p->operating_state = I2C1_SEND_STOP;

                    I2C1CONbits.ACKDT = 1;  // NACK

                    I2C1CONbits.ACKEN = 1;

                }

                break;

            case I2C1_REQ_DATA:

                // Set module to receive one byte of data

                i2c_data_p->operating_state = I2C1_RCV_DATA;

                I2C1CONbits.RCEN = 1;

                break;

            case I2C1_SEND_STOP:

                // Send the stop bit

                i2c_data_p->operating_state = I2C1_STOPPED;

                I2C1CONbits.PEN = 1;

                i2c_data_p->return_status = I2C1_RECV_OK;

                break;

            case I2C1_STOPPED:

                i2c_data_p->operating_state = I2C1_IDLE;

                i2c_data_p->master_status = I2C1_MASTER_IDLE;

                break;

        }

    } else if (i2c_data_p->master_status == I2C1_MASTER_RESTART) {

        switch (i2c_data_p->operating_state) {

            case I2C1_IDLE:

                break;

            case I2C1_SEND_ADDR:

                // Send the address with read bit set

                i2c_data_p->operating_state = I2C1_CHECK_ACK_SEND;

                I2C1TRN = (i2c_data_p->master_dest_addr << 1) | 0x0;

                break;

            case I2C1_CHECK_ACK_SEND:

                // Check if ACK is received or not

                if (!I2C1STATbits.ACKSTAT) {

                    // If an ACK is received, send first byte of data

                    I2C1TRN = i2c_data_p->buffer_in[0];

                    i2c_data_p->operating_state = I2C1_CHECK_ACK_RESTART;

                } else {

                    // If a NACK is received, stop transmission and send error

                    i2c_data_p->operating_state = I2C1_STOPPED;

                    I2C1CONbits.PEN = 1;

                    i2c_data_p->return_status = I2C1_SEND_FAIL;

                }

                break;

            case I2C1_CHECK_ACK_RESTART:

                if (!I2C1STATbits.ACKSTAT) {

                    I2C1CONbits.RSEN = 1;

                    i2c_data_p->operating_state = I2C1_SEND_ADDR_2;

                } else {

                    // If a NACK is received, stop transmission and send error

                    i2c_data_p->operating_state = I2C1_STOPPED;

                    I2C1CONbits.PEN = 1;

                    i2c_data_p->return_status = I2C1_SEND_FAIL;

                }

                break;

            case I2C1_SEND_ADDR_2:

                // Send the address with read bit set

                i2c_data_p->operating_state = I2C1_CHECK_ACK_RECV;

                I2C1TRN = (i2c_data_p->master_dest_addr << 1) | 0x1;

                break;

            case I2C1_CHECK_ACK_RECV:

                // Check if ACK is received

                if (!I2C1STATbits.ACKSTAT) {

                    // If an ACK is received, set module to receive 1 byte of data

                    i2c_data_p->operating_state = I2C1_RCV_DATA;

                    I2C1CONbits.RCEN = 1;

                } else {

                    // If a NACK is received, stop transmission and send error

                    i2c_data_p->operating_state = I2C1_STOPPED;

                    I2C1CONbits.PEN = 1;

                    i2c_data_p->return_status = I2C1_RECV_FAIL;

                }

                break;

            case I2C1_RCV_DATA:

                // On receive, save byte into buffer

                // TODO: Handle possible I2C buffer overflow

                i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = I2C1RCV;

                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 = I2C1_REQ_DATA;

                    I2C1CONbits.ACKDT = 0;  // ACK

                    I2C1CONbits.ACKEN = 1;

                } else {

                    // If we are done reading, send an NACK to the slave

                    i2c_data_p->operating_state = I2C1_SEND_STOP;

                    I2C1CONbits.ACKDT = 1;  // NACK

                    I2C1CONbits.ACKEN = 1;

                }

                break;

            case I2C1_REQ_DATA:

                // Set module to receive one byte of data

                i2c_data_p->operating_state = I2C1_RCV_DATA;

                I2C1CONbits.RCEN = 1;

                break;

            case I2C1_SEND_STOP:

                // Send the stop bit

                i2c_data_p->operating_state = I2C1_STOPPED;

                I2C1CONbits.PEN = 1;

                i2c_data_p->return_status = I2C1_RECV_OK;

                break;

            case I2C1_STOPPED:

                i2c_data_p->operating_state = I2C1_IDLE;

                i2c_data_p->master_status = I2C1_MASTER_IDLE;

                break;

        }

    }

}

void I2C1_Interrupt_Slave() {

    // !!WARNING!! THIS CODE DOES -NOT- HAVE ANY ERROR HANDLING !!

    // TODO: Add error handling to this interrupt function

    /* The PIC32 family has different slave interrupts than the PIC8 family

     * Slave mode operations that generate a slave interrupt are:

     * 1. Detection of a valid device address (including general call)

     * 2. Reception of data

     * 3. Request to transmit data

     */

    uint8_t received_data;

    uint8_t data_read_from_buffer = 0;

    uint8_t data_written_to_buffer = 0;

    uint8_t overrun_error = 0;

    // Clear SSPOV (overflow bit)

    if (I2C1STATbits.I2COV == 1) {

        I2C1STATbits.I2COV = 0;

        overrun_error = 1;

        i2c_data_p->return_status = I2C1_ERR_OVERRUN;

    }

    // Read SPPxBUF if it is full

    if (I2C1STATbits.RBF == 1) {

        received_data = I2C1RCV;

        data_read_from_buffer = 1;

    }

    if (!overrun_error) {

        if (I2C1STATbits.R_W == 0) {

            // Slave is receiving data

            i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = received_data;

            if (i2c_data_p->buffer_in_write_ind == MAXI2C1BUF - 1) {

                i2c_data_p->buffer_in_write_ind = 0;

            } else {

                i2c_data_p->buffer_in_write_ind++;

            }

            if (i2c_data_p->buffer_in_len < MAXI2C1BUF - 1) {

                i2c_data_p->buffer_in_len++;

            }

            i2c_data_p->slave_in_last_byte = received_data;

            i2c_data_p->return_status = I2C1_RECV_OK;

        } else {

            // Slave is returning data

            if (!i2c_data_p->slave_sending_data) {

                // If we are not currently sending data, figure out what to reply with

                if (I2C1_Process_Request(i2c_data_p->slave_in_last_byte)) {

                    // Data exists to be returned, send first byte

                    I2C1TRN = i2c_data_p->buffer_out[0];

                    data_written_to_buffer = 1;

                    i2c_data_p->buffer_out_ind = 1;

                    i2c_data_p->slave_sending_data = 1;

                } else {

                    // Unknown request, fill rest of request with 0s

                    I2C1TRN = 0x0;

                    data_written_to_buffer = 1;

                    i2c_data_p->slave_sending_data = 0;

                    i2c_data_p->return_status = I2C1_SEND_FAIL;

                }

            } else {

                // Sending remaining data back to master

                if (i2c_data_p->buffer_out_ind < i2c_data_p->buffer_out_len) {

                    I2C1TRN = i2c_data_p->buffer_out[i2c_data_p->buffer_out_ind];

                    data_written_to_buffer = 1;

                    i2c_data_p->buffer_out_ind++;

                } else {

                    // Nothing left to send, fill rest of request with 0s

                    I2C1TRN = 0x0;

                    data_written_to_buffer = 1;

                    i2c_data_p->slave_sending_data = 0;

                    i2c_data_p->return_status = I2C1_SEND_OK;

                }

            }

        }

    }

    // Release the clock stretching bit (if we should)

    if (data_read_from_buffer || data_written_to_buffer) {

        // Release the clock

        if (I2C1CONbits.SCLREL == 0) {

            I2C1CONbits.SCLREL = 1;

        }

    }

}

/* Returns 0 if I2C module is currently busy, otherwise returns status code */

uint8_t I2C1_Get_Status() {

        if (i2c_data_p->master_status == I2C1_MASTER_IDLE &&

                i2c_data_p->operating_state == I2C1_IDLE &&

                I2C1STATbits.TBF == 0) {

            return i2c_data_p->return_status;

        } else {

            return 0;

        }

}

uint8_t I2C1_Buffer_Len() {

    return i2c_data_p->buffer_in_len;

}

/* Returns 0 if I2C module is currently busy, otherwise returns buffer length */

uint8_t I2C1_Read_Buffer(uint8_t *buffer) {

    uint32_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 == MAXI2C1BUF-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;

}

/* Put data to be returned here */

uint8_t I2C1_Process_Request(uint8_t c) {

    uint8_t ret = 0;

    switch (c) {

        case 0x01:

            i2c_data_p->buffer_out[0] = 0x12;

            i2c_data_p->buffer_out_len = 1;

            ret = 1;

            break;

        case 0x02:

            i2c_data_p->buffer_out[0] = 0x34;

            i2c_data_p->buffer_out[1] = 0x56;

            i2c_data_p->buffer_out_len = 2;

            ret = 1;

            break;

    }

    return ret;

}