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#include <xc.h>
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#include <plib.h>
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#include "defines.h"
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#include "SPI4.h"
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static SPI4_DATA *spi_data_ptr;
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void SPI4_Init(SPI4_DATA *data) {
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spi_data_ptr = data;
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spi_data_ptr->buffer_out_ind = 0;
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spi_data_ptr->buffer_out_len = 0;
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spi_data_ptr->buffer_in_ind = 0;
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spi_data_ptr->buffer_in_len = 0;
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spi_data_ptr->write_blank = 0;
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INTDisableInterrupts();
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// Note: FIFO enhanced buffer depth is 4/8/16 for 32/16/8 bit widths
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// FSCK = FPB / (2 * (SPIxBRG + 1))
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IEC1CLR = 0x00000700; // Disable all SPI interrupts
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SPI4CON = 0; // Stops and resets the SPI4.
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int tmp = SPI4BUF; // Clears the receive buffer
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IFS1CLR = 0x00000700; // Clear any existing event
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IPC8CLR = 0x0000001F; // Clear the priority
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IPC8SET = 0x0000001A; // Set IPL=6, Subpriority 2
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SPI4BRG = 0x4; // Use FPB/10 clock frequency
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SPI4STATCLR = 0x40; // Clear the Overflow
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IEC1SET = 0x00000300; // Enable RX and Error interrupts
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// Enhanced buffer, SPI on, 8 bits transfer, SMP=1, Master mode
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// SPIxTXIF set on buffer empty, SPIxRXIF set on buffer not empty
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SPI4CON = 0x18225;
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INTEnableInterrupts();
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}
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int SPI4_Read(int length, void (*rx_callback)(char, char *)) {
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spi_data_ptr->rx_callback = rx_callback;
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// Ensure that the receiving buffer is large enough
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if (length > SPI4_BUFFER_IN_SIZE)
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return 0;
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// Ensure that no previous transactions are in progress
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if (spi_data_ptr->buffer_in_len != 0)
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return 0;
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spi_data_ptr->write_blank = 1;
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spi_data_ptr->buffer_in_len = length;
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spi_data_ptr->buffer_in_ind = 0;
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SPI4_Write(NULL, length, NULL);
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return 1;
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}
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int SPI4_Write(char *array, int length, void (*tx_callback)(void)) {
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spi_data_ptr->tx_callback = tx_callback;
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// We only care about the transmit length if we are sending data
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if (length > SPI4_BUFFER_OUT_SIZE && !spi_data_ptr->write_blank)
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return 0;
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// Ensure that no previous transactions are in progress
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if (spi_data_ptr->buffer_out_len != 0)
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return 0;
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// Put the data to send into the outbound buffer
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spi_data_ptr->buffer_out_len = length;
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spi_data_ptr->buffer_out_ind = 0;
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// Copy only if we are actually going to transmit data
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if (!spi_data_ptr->write_blank) {
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int i;
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for (i = 0; i < length; i++) {
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spi_data_ptr->buffer_out[i] = array[i];
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}
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}
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IEC1SET = 0x00000400; // Enable TX interrupt
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return 1;
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}
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void __ISR(_SPI_4_VECTOR, ipl6) __SPI_4_Interrupt_Handler(void) {
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// Process SPI4 error flag
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if (IFS1bits.SPI4EIF) {
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// Clear the receive overflow bit if it is set
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if (SPI4STATbits.SPIROV) {
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SPI4STATbits.SPIROV = 0;
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}
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IFS1CLR = 0x00000100; // Clear the error flag
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}
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// Process SPI4 receive flag
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if (IFS1bits.SPI4RXIF) {
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int i;
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// Read the data received from the last transfer
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int rxBufferCount = SPI4STATbits.RXBUFELM;
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for (i = 0; i < rxBufferCount; i++) {
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char c = SPI4BUF;
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// Put the received data into the buffer
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if (spi_data_ptr->buffer_in_len != 0) {
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spi_data_ptr->buffer_in[spi_data_ptr->buffer_in_ind] = c;
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spi_data_ptr->buffer_in_ind++;
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// If done acquiring requested length, reset
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if (spi_data_ptr->buffer_in_ind == spi_data_ptr->buffer_in_len) {
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// Call the RX callback function on the received data
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if (spi_data_ptr->rx_callback != NULL)
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(*spi_data_ptr->rx_callback)(spi_data_ptr->buffer_in_len, spi_data_ptr->buffer_in);
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spi_data_ptr->buffer_in_len = 0;
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}
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}
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}
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IFS1CLR = 0x00000200; // Clear the RX flag
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}
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// Process SPI4 transmit flag
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if (IFS1bits.SPI4TXIF && IEC1bits.SPI4TXIE) {
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int i;
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// Disable the transmit interrupt if all data has been sent
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if (spi_data_ptr->buffer_out_len == 0) {
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IEC1CLR=0x00000400;
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spi_data_ptr->write_blank = 0;
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// Call the TX callback function at end of transmission
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if (spi_data_ptr->tx_callback != NULL)
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(*spi_data_ptr->tx_callback)();
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} else {
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// Start transmitting the data in the buffer
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int txBufferFree = 16 - SPI4STATbits.TXBUFELM;
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if (spi_data_ptr->buffer_out_len > txBufferFree) {
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for (i = 0; i < txBufferFree; i++) {
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if (spi_data_ptr->write_blank) {
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SPI4BUF = 0x00;
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} else {
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SPI4BUF = spi_data_ptr->buffer_out[spi_data_ptr->buffer_out_ind];
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spi_data_ptr->buffer_out_ind++;
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}
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}
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spi_data_ptr->buffer_out_len -= txBufferFree;
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} else {
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for (i = 0; i < spi_data_ptr->buffer_out_len; i++) {
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if (spi_data_ptr->write_blank) {
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SPI4BUF = 0x00;
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} else {
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SPI4BUF = spi_data_ptr->buffer_out[spi_data_ptr->buffer_out_ind];
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spi_data_ptr->buffer_out_ind++;
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}
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}
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spi_data_ptr->buffer_out_len = 0;
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}
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}
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IFS1CLR = 0x00000400; // Clear the TX flag
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}
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}
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