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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 "UART1.h"
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static UART1_DATA *uart_data_ptr;
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/* Note: BRGH values are different from PIC18!
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*
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* Baud Rate Calculation (BRGH = 0):
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* Baud Rate = PerfBusFreq / (16 * (BRG + 1))
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* BRG = PerfBusFreq / (16 * Baud Rate) - 1
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*
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* Baud Rate Calculation (BRGH = 1):
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* Baud Rate = PerfBusFreq / (4 * (BRG + 1))
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* BRG = PerfBusFreq / (4 * Baud Rate) - 1
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*/
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void UART1_Init(UART1_DATA *data, void (*rx_callback)(char)) {
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uart_data_ptr = data;
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uart_data_ptr->rx_callback = rx_callback;
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uart_data_ptr->buffer_out_len = 0;
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uart_data_ptr->buffer_out_ind = 0;
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INTDisableInterrupts();
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IEC0CLR = 0x1C000000; // Disable all UART1 interrupts
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IFS0CLR = 0x1C000000; // Clear any existing events
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IPC6SET = 0x00000009; // Set Priority = 2, Subpriority = 1
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U1MODE = 0x00008008; // UART enabled, BRGH = 1
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U1STA = 0x00009400; // TX interrupt on buffer empty, RX interrupt on buffer not empty
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// U1BRG = 173; // Set baud rate to 115200 @ 80MHz (0.22% error)
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U1BRG = 86; // Set baud rate to 230400 @ 80MHz (0.22% error)
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// U1BRG = 77; // Set baud rate to 256000 @ 80MHz (0.12% error)
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// U1BRG = 42; // Set baud rate to 460800 @ 80MHz (0.94% error)
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// U1BRG = 21; // Set baud rate to 921600 @ 80MHz (1.36% error)
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IEC0SET = 0x0C000000; // Enable the RX and Error interrupts
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INTEnableInterrupts();
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TRISDbits.TRISD14 = 0;
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PORTDbits.RD14 = 0;
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}
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int UART1_Write(char *string, int length) {
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if (length > UART1_BUFFER_SIZE)
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return 0;
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if (uart_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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uart_data_ptr->buffer_out_len = length;
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uart_data_ptr->buffer_out_ind = 0;
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int i;
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for (i = 0; i < length; i++) {
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uart_data_ptr->buffer_out[i] = string[i];
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}
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IEC0SET = 0x10000000; // Enable TX interrupt
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return 1;
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}
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void __ISR(_UART_1_VECTOR, ipl2) __UART_1_Interrupt_Handler(void) {
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PORTDbits.RD14 = 1;
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// Process UART1 error flag
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if (IFS0bits.U1EIF) {
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if (U1STAbits.PERR) { // Process parity error
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}
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if (U1STAbits.FERR) { // Process frame error
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}
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if (U1STAbits.OERR) { // Process receive buffer overrun error
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U1STAbits.OERR = 0; // Clear the overrun error if set
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}
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IFS0CLR = 0x04000000; // Clear the error flag
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}
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// Process UART1 recieve flag
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if (IFS0bits.U1RXIF) {
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// Read the data received from the last transfer
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while (U1STAbits.URXDA) {
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char c = U1RXREG;
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// Call the RX callback function on each received data
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if (uart_data_ptr->rx_callback != NULL) {
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(*uart_data_ptr->rx_callback)(c);
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}
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}
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IFS0CLR = 0x08000000; // Clear the recieve flag
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}
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// Process UART1 transmit flag
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if (IFS0bits.U1TXIF && IEC0bits.U1TXIE) {
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// Disable the transmit interrupt if all data has been sent
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if (uart_data_ptr->buffer_out_ind == uart_data_ptr->buffer_out_len) {
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IEC0CLR = 0x10000000;
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uart_data_ptr->buffer_out_len = 0;
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} else {
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// Start filling the transmit buffer
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while (!U1STAbits.UTXBF) {
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U1TXREG = uart_data_ptr->buffer_out[uart_data_ptr->buffer_out_ind];
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uart_data_ptr->buffer_out_ind++;
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if (uart_data_ptr->buffer_out_ind == uart_data_ptr->buffer_out_len)
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break;
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}
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}
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IFS0CLR = 0x10000000; // Clear the transmit flag
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}
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PORTDbits.RD14 = 0;
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}
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