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Kevin |
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#include "defines.h"
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#include "I2C1.h"
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static I2C1_DATA *i2c_data_p;
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// Initialize the data structures, should be called once before any I2C routines are called
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void I2C1_Init(I2C1_DATA *data, uint8_t speed, uint8_t address) {
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i2c_data_p = data;
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i2c_data_p->buffer_in_len = 0;
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i2c_data_p->buffer_in_read_ind = 0;
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i2c_data_p->buffer_in_write_ind = 0;
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i2c_data_p->buffer_out_ind = 0;
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i2c_data_p->buffer_out_len = 0;
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i2c_data_p->operating_state = I2C1_IDLE;
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i2c_data_p->return_status = 0;
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i2c_data_p->slave_in_last_byte = 0;
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i2c_data_p->slave_sending_data = 0;
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i2c_data_p->master_dest_addr = 0;
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i2c_data_p->master_status = I2C1_MASTER_IDLE;
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INTDisableInterrupts();
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// Enable the I2C module and set the clock stretch enable bit
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// Note: Automatically overrides any other pin settings
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I2C1CONSET = 0x00008040;
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I2C1ADD = address;
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if (!speed) I2C1BRG = 0x05A; // Operate at 400kHZ (80MHz)
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else I2C1BRG = 0x186; // Operate at 100kHZ (80MHz)
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IFS0CLR = 0xE0000000; // Clear any existing events
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IPC6CLR = 0x00001F00; // Reset priority levels
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IPC6SET = 0x00001500; // Set IPL=5, Subpriority 1
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IEC0SET = 0xE0000000; // Enable I2C1 interrupts
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INTEnableInterrupts();
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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 I2C1_Master_Send(uint8_t address, uint8_t *msg, uint32_t length) {
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uint32_t 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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i2c_data_p->buffer_in[i] = msg[i];
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}
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i2c_data_p->buffer_in_len = length;
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i2c_data_p->master_dest_addr = address;
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i2c_data_p->buffer_in_read_ind = 0;
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i2c_data_p->buffer_in_write_ind = 0;
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// Change status to 'next' operation
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i2c_data_p->operating_state = I2C1_SEND_ADDR;
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i2c_data_p->master_status = I2C1_MASTER_SEND;
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// Generate start condition
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I2C1CONbits.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 I2C1_Master_Recv(uint8_t address, uint32_t 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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i2c_data_p->buffer_in_len = length;
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i2c_data_p->master_dest_addr = address;
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i2c_data_p->buffer_in_read_ind = 0;
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i2c_data_p->buffer_in_write_ind = 0;
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// Change status to 'next' operation
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i2c_data_p->operating_state = I2C1_SEND_ADDR;
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i2c_data_p->master_status = I2C1_MASTER_RECV;
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// Generate start condition
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I2C1CONbits.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 I2C1_Master_Restart(uint8_t address, uint8_t msg, uint32_t length) {
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uint8_t c;
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if (length == 0) {
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c = msg;
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I2C1_Master_Send(address, &c, 1);
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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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i2c_data_p->buffer_in[0] = msg;
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i2c_data_p->buffer_in_len = length;
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i2c_data_p->master_dest_addr = address;
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i2c_data_p->buffer_in_read_ind = 0;
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i2c_data_p->buffer_in_write_ind = 0;
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// Change status to 'next' operation
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i2c_data_p->operating_state = I2C1_SEND_ADDR;
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i2c_data_p->master_status = I2C1_MASTER_RESTART;
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// Generate start condition
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I2C1CONbits.SEN = 1;
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}
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void __ISR(_I2C_1_VECTOR, ipl5) __I2C_1_Interrupt_Handler(void) {
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// Bus collision event
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if (IFS0bits.I2C1BIF) {
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// This should be handled at some point
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IFS0CLR = 0x20000000;
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}
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// Slave event
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if (IFS0bits.I2C1SIF) {
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I2C1_Interrupt_Slave();
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IFS0CLR = 0x40000000;
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}
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// Master event
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if (IFS0bits.I2C1MIF) {
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I2C1_Interrupt_Master();
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IFS0CLR = 0x80000000;
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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 I2C1_Interrupt_Master() {
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/* The PIC32 family has different master interrupts than the PIC8 family
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* Master mode operations that generate a slave interrupt are:
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* 1. Start condition
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* 2. Repeated start sequence
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* 3. Stop condition
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* 4. Data transfer byte received
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* 5. During a send ACK or NACK sequence to slave
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* 6. Data transfer byte transmitted
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* 7. During a slave-detected stop
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*/
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// If we are in the middle of sending data
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if (i2c_data_p->master_status == I2C1_MASTER_SEND) {
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switch (i2c_data_p->operating_state) {
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case I2C1_IDLE:
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break;
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case I2C1_SEND_ADDR:
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// Send the address with read bit set
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i2c_data_p->operating_state = I2C1_CHECK_ACK_SEND;
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I2C1TRN = (i2c_data_p->master_dest_addr << 1) | 0x0;
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break;
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case I2C1_CHECK_ACK_SEND:
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// Check if ACK is received or not
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if (!I2C1STATbits.ACKSTAT) {
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// If an ACK is received, send next byte of data
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if (i2c_data_p->buffer_in_read_ind < i2c_data_p->buffer_in_len) {
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I2C1TRN = i2c_data_p->buffer_in[i2c_data_p->buffer_in_read_ind];
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i2c_data_p->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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i2c_data_p->operating_state = I2C1_IDLE;
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I2C1CONbits.PEN = 1;
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i2c_data_p->master_status = I2C1_MASTER_IDLE;
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i2c_data_p->return_status = I2C1_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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i2c_data_p->operating_state = I2C1_IDLE;
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I2C1CONbits.PEN = 1;
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i2c_data_p->master_status = I2C1_MASTER_IDLE;
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i2c_data_p->return_status = I2C1_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 (i2c_data_p->master_status == I2C1_MASTER_RECV) {
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switch (i2c_data_p->operating_state) {
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case I2C1_IDLE:
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break;
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case I2C1_SEND_ADDR:
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// Send address with write bit set
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i2c_data_p->operating_state = I2C1_CHECK_ACK_RECV;
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I2C1TRN = (i2c_data_p->master_dest_addr << 1) | 0x1;
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break;
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case I2C1_CHECK_ACK_RECV:
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// Check if ACK is received
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if (!I2C1STATbits.ACKSTAT) {
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// If an ACK is received, set module to receive 1 byte of data
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i2c_data_p->operating_state = I2C1_RCV_DATA;
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I2C1CONbits.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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i2c_data_p->operating_state = I2C1_IDLE;
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I2C1CONbits.PEN = 1;
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i2c_data_p->master_status = I2C1_MASTER_IDLE;
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i2c_data_p->return_status = I2C1_RECV_FAIL;
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}
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break;
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case I2C1_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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i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = I2C1RCV;
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i2c_data_p->buffer_in_write_ind++;
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if (i2c_data_p->buffer_in_write_ind < i2c_data_p->buffer_in_len) {
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// If we still need to read, send an ACK to the slave
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i2c_data_p->operating_state = I2C1_REQ_DATA;
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I2C1CONbits.ACKDT = 0; // ACK
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I2C1CONbits.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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i2c_data_p->operating_state = I2C1_SEND_STOP;
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I2C1CONbits.ACKDT = 1; // NACK
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I2C1CONbits.ACKEN = 1;
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}
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break;
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case I2C1_REQ_DATA:
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// Set module to receive one byte of data
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i2c_data_p->operating_state = I2C1_RCV_DATA;
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I2C1CONbits.RCEN = 1;
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break;
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case I2C1_SEND_STOP:
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// Send the stop bit and copy message to send to Main()
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i2c_data_p->operating_state = I2C1_IDLE;
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I2C1CONbits.PEN = 1;
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i2c_data_p->master_status = I2C1_MASTER_IDLE;
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i2c_data_p->return_status = I2C1_RECV_OK;
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break;
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}
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} else if (i2c_data_p->master_status == I2C1_MASTER_RESTART) {
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switch (i2c_data_p->operating_state) {
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case I2C1_IDLE:
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break;
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case I2C1_SEND_ADDR:
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// Send the address with read bit set
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i2c_data_p->operating_state = I2C1_CHECK_ACK_SEND;
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I2C1TRN = (i2c_data_p->master_dest_addr << 1) | 0x0;
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break;
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case I2C1_CHECK_ACK_SEND:
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// Check if ACK is received or not
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if (!I2C1STATbits.ACKSTAT) {
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// If an ACK is received, send first byte of data
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I2C1TRN = i2c_data_p->buffer_in[0];
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i2c_data_p->operating_state = I2C1_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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i2c_data_p->operating_state = I2C1_IDLE;
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I2C1CONbits.PEN = 1;
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i2c_data_p->master_status = I2C1_MASTER_IDLE;
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i2c_data_p->return_status = I2C1_SEND_FAIL;
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}
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break;
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case I2C1_CHECK_ACK_RESTART:
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if (!I2C1STATbits.ACKSTAT) {
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I2C1CONbits.RSEN = 1;
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i2c_data_p->operating_state = I2C1_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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i2c_data_p->operating_state = I2C1_IDLE;
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I2C1CONbits.PEN = 1;
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i2c_data_p->master_status = I2C1_MASTER_IDLE;
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i2c_data_p->return_status = I2C1_SEND_FAIL;
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}
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break;
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case I2C1_SEND_ADDR_2:
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// Send the address with read bit set
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i2c_data_p->operating_state = I2C1_CHECK_ACK_RECV;
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I2C1TRN = (i2c_data_p->master_dest_addr << 1) | 0x1;
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break;
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case I2C1_CHECK_ACK_RECV:
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// Check if ACK is received
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269 |
if (!I2C1STATbits.ACKSTAT) {
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// If an ACK is received, set module to receive 1 byte of data
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271 |
i2c_data_p->operating_state = I2C1_RCV_DATA;
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I2C1CONbits.RCEN = 1;
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273 |
} else {
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// If a NACK is received, stop transmission and send error
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275 |
i2c_data_p->operating_state = I2C1_IDLE;
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I2C1CONbits.PEN = 1;
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277 |
i2c_data_p->master_status = I2C1_MASTER_IDLE;
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i2c_data_p->return_status = I2C1_RECV_FAIL;
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}
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280 |
break;
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case I2C1_RCV_DATA:
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// On receive, save byte into buffer
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283 |
// TODO: Handle I2C buffer overflow
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284 |
i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = I2C1RCV;
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i2c_data_p->buffer_in_write_ind++;
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286 |
if (i2c_data_p->buffer_in_write_ind < i2c_data_p->buffer_in_len) {
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287 |
// If we still need to read, send an ACK to the slave
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288 |
i2c_data_p->operating_state = I2C1_REQ_DATA;
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289 |
I2C1CONbits.ACKDT = 0; // ACK
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290 |
I2C1CONbits.ACKEN = 1;
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291 |
} else {
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292 |
// If we are done reading, send an NACK to the slave
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293 |
i2c_data_p->operating_state = I2C1_SEND_STOP;
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294 |
I2C1CONbits.ACKDT = 1; // NACK
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295 |
I2C1CONbits.ACKEN = 1;
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296 |
}
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297 |
break;
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298 |
case I2C1_REQ_DATA:
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299 |
// Set module to receive one byte of data
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300 |
i2c_data_p->operating_state = I2C1_RCV_DATA;
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301 |
I2C1CONbits.RCEN = 1;
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302 |
break;
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303 |
case I2C1_SEND_STOP:
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304 |
// Send the stop bit and copy message to send to Main()
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|
305 |
i2c_data_p->operating_state = I2C1_IDLE;
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|
306 |
I2C1CONbits.PEN = 1;
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|
|
307 |
i2c_data_p->master_status = I2C1_MASTER_IDLE;
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|
|
308 |
i2c_data_p->return_status = I2C1_RECV_OK;
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|
|
309 |
break;
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|
310 |
}
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|
311 |
}
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|
312 |
}
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|
313 |
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|
|
314 |
void I2C1_Interrupt_Slave() {
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|
|
315 |
// !!WARNING!! THIS CODE DOES -NOT- HAVE ANY ERROR HANDLING !!
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|
|
316 |
// TODO: Add error handling to this interrupt function
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|
|
317 |
|
|
|
318 |
/* The PIC32 family has different slave interrupts than the PIC8 family
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|
319 |
* Slave mode operations that generate a slave interrupt are:
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|
320 |
* 1. Detection of a valid device address (including general call)
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|
321 |
* 2. Reception of data
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|
322 |
* 3. Request to transmit data
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|
323 |
*/
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|
324 |
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|
325 |
uint8_t received_data;
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|
326 |
uint8_t data_read_from_buffer = 0;
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|
327 |
uint8_t data_written_to_buffer = 0;
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|
|
328 |
uint8_t overrun_error = 0;
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|
|
329 |
|
|
|
330 |
// Clear SSPOV (overflow bit)
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|
331 |
if (I2C1STATbits.I2COV == 1) {
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|
332 |
I2C1STATbits.I2COV = 0;
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|
333 |
overrun_error = 1;
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|
334 |
i2c_data_p->return_status = I2C1_ERR_OVERRUN;
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|
335 |
}
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|
336 |
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|
337 |
// Read SPPxBUF if it is full
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|
338 |
if (I2C1STATbits.RBF == 1) {
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|
339 |
received_data = I2C1RCV;
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|
340 |
data_read_from_buffer = 1;
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|
|
341 |
}
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|
|
342 |
|
|
|
343 |
if (!overrun_error) {
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|
|
344 |
if (I2C1STATbits.R_W == 0) {
|
|
|
345 |
// Slave is receiving data
|
|
|
346 |
i2c_data_p->buffer_in[i2c_data_p->buffer_in_write_ind] = received_data;
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|
|
347 |
if (i2c_data_p->buffer_in_write_ind == MAXI2C1BUF - 1) {
|
|
|
348 |
i2c_data_p->buffer_in_write_ind = 0;
|
|
|
349 |
} else {
|
|
|
350 |
i2c_data_p->buffer_in_write_ind++;
|
|
|
351 |
}
|
|
|
352 |
if (i2c_data_p->buffer_in_len < MAXI2C1BUF - 1) {
|
|
|
353 |
i2c_data_p->buffer_in_len++;
|
|
|
354 |
}
|
|
|
355 |
i2c_data_p->slave_in_last_byte = received_data;
|
|
|
356 |
i2c_data_p->return_status = I2C1_RECV_OK;
|
|
|
357 |
} else {
|
|
|
358 |
// Slave is returning data
|
|
|
359 |
if (!i2c_data_p->slave_sending_data) {
|
|
|
360 |
// If we are not currently sending data, figure out what to reply with
|
|
|
361 |
if (I2C1_Process_Request(i2c_data_p->slave_in_last_byte)) {
|
|
|
362 |
// Data exists to be returned, send first byte
|
|
|
363 |
I2C1TRN = i2c_data_p->buffer_out[0];
|
|
|
364 |
data_written_to_buffer = 1;
|
|
|
365 |
i2c_data_p->buffer_out_ind = 1;
|
|
|
366 |
i2c_data_p->slave_sending_data = 1;
|
|
|
367 |
} else {
|
|
|
368 |
// Unknown request, fill rest of request with 0s
|
|
|
369 |
I2C1TRN = 0x0;
|
|
|
370 |
data_written_to_buffer = 1;
|
|
|
371 |
i2c_data_p->slave_sending_data = 0;
|
|
|
372 |
i2c_data_p->return_status = I2C1_SEND_FAIL;
|
|
|
373 |
}
|
|
|
374 |
} else {
|
|
|
375 |
// Sending remaining data back to master
|
|
|
376 |
if (i2c_data_p->buffer_out_ind < i2c_data_p->buffer_out_len) {
|
|
|
377 |
I2C1TRN = i2c_data_p->buffer_out[i2c_data_p->buffer_out_ind];
|
|
|
378 |
data_written_to_buffer = 1;
|
|
|
379 |
i2c_data_p->buffer_out_ind++;
|
|
|
380 |
} else {
|
|
|
381 |
// Nothing left to send, fill rest of request with 0s
|
|
|
382 |
I2C1TRN = 0x0;
|
|
|
383 |
data_written_to_buffer = 1;
|
|
|
384 |
i2c_data_p->slave_sending_data = 0;
|
|
|
385 |
i2c_data_p->return_status = I2C1_SEND_OK;
|
|
|
386 |
}
|
|
|
387 |
}
|
|
|
388 |
}
|
|
|
389 |
}
|
|
|
390 |
|
|
|
391 |
// Release the clock stretching bit (if we should)
|
|
|
392 |
if (data_read_from_buffer || data_written_to_buffer) {
|
|
|
393 |
// Release the clock
|
|
|
394 |
if (I2C1CONbits.SCLREL == 0) {
|
|
|
395 |
I2C1CONbits.SCLREL = 1;
|
|
|
396 |
}
|
|
|
397 |
}
|
|
|
398 |
}
|
|
|
399 |
|
|
|
400 |
/* Returns 0 if I2C module is currently busy, otherwise returns status code */
|
|
|
401 |
uint8_t I2C1_Get_Status() {
|
|
|
402 |
if (i2c_data_p->master_status != I2C1_MASTER_IDLE ||
|
|
|
403 |
i2c_data_p->buffer_in_len == 0) {
|
|
|
404 |
return 0;
|
|
|
405 |
} else {
|
|
|
406 |
return i2c_data_p->return_status;
|
|
|
407 |
}
|
|
|
408 |
}
|
|
|
409 |
|
|
|
410 |
uint8_t I2C1_Buffer_Len() {
|
|
|
411 |
return i2c_data_p->buffer_in_len;
|
|
|
412 |
}
|
|
|
413 |
|
|
|
414 |
/* Returns 0 if I2C module is currently busy, otherwise returns buffer length */
|
|
|
415 |
uint8_t I2C1_Read_Buffer(uint8_t *buffer) {
|
|
|
416 |
uint32_t i = 0;
|
|
|
417 |
while (i2c_data_p->buffer_in_len != 0) {
|
|
|
418 |
buffer[i] = i2c_data_p->buffer_in[i2c_data_p->buffer_in_read_ind];
|
|
|
419 |
i++;
|
|
|
420 |
if (i2c_data_p->buffer_in_read_ind == MAXI2C1BUF-1) {
|
|
|
421 |
i2c_data_p->buffer_in_read_ind = 0;
|
|
|
422 |
} else {
|
|
|
423 |
i2c_data_p->buffer_in_read_ind++;
|
|
|
424 |
}
|
|
|
425 |
i2c_data_p->buffer_in_len--;
|
|
|
426 |
}
|
|
|
427 |
return i;
|
|
|
428 |
}
|
|
|
429 |
|
|
|
430 |
/* Put data to be returned here */
|
|
|
431 |
uint8_t I2C1_Process_Request(uint8_t c) {
|
|
|
432 |
uint8_t ret = 0;
|
|
|
433 |
switch (c) {
|
|
|
434 |
case 0x01:
|
|
|
435 |
i2c_data_p->buffer_out[0] = 0x12;
|
|
|
436 |
i2c_data_p->buffer_out_len = 1;
|
|
|
437 |
ret = 1;
|
|
|
438 |
break;
|
|
|
439 |
case 0x02:
|
|
|
440 |
i2c_data_p->buffer_out[0] = 0x34;
|
|
|
441 |
i2c_data_p->buffer_out[1] = 0x56;
|
|
|
442 |
i2c_data_p->buffer_out_len = 2;
|
|
|
443 |
ret = 1;
|
|
|
444 |
break;
|
|
|
445 |
}
|
|
|
446 |
return ret;
|
|
|
447 |
}
|