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145 lines
3.8 KiB
C
145 lines
3.8 KiB
C
/*
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* UART.c
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*
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* Created: 25/11/2021 16:26:10
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* Author: n0x
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*/
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#include "UART.h"
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/* create structs for TX and TX buffer */
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CircularBuffer TxBuffer;
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CircularBuffer* pTxBuffer = &TxBuffer;
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CircularBuffer RxBuffer;
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CircularBuffer* pRxBuffer = &RxBuffer;
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volatile uint8_t TxActive;
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void
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uart_init(void) {
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UBRR0 = 103; /* set BAUD rate to 9600 */
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UCSR0C |=
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(0<<UMSEL00)|(0<<UMSEL01)| /* Async UART */
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(0<<UPM00)|(0<<UPM01)| /* Disable Parity */
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(1<<UCSZ00)|(1<<UCSZ01)| /* 8 Bit */
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(0<<USBS0); /* 1 Stopbit */
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UCSR0B |=
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(1<<TXEN0)|(1<<RXEN0)| /* enable send and receive */
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(1<<RXCIE0); /* enable Receive interrupts */
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/* Initiate read- and write-pointers with 0 */
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pTxBuffer->Readpointer = 0;
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pTxBuffer->Writepointer = 0;
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pRxBuffer->Readpointer = 0;
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pRxBuffer->Writepointer = 0;
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}
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/********Sending Data********/
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void
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uart_send_string(char* string) {
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/* Take a whole string and transmit every char from it */
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int i = 0;
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while(string[i] != '\0'){
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uart_send_byte(string[i]);
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i++;
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}
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}
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void
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uart_send_byte(char c) {
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/* Disable the TX Interrupt to prevent issues while writing to the send buffer*/
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UCSR0B &= ~(1<<TXCIE0);
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/* Check if a transmit is in progress
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if yes -> write the byte to the buffer
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if no -> write the byte to the UDR0 register and enable the transmit in progress flag
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*/
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if(TxActive){
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pTxBuffer->data[pTxBuffer->Writepointer++] = c;
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if (pTxBuffer->Writepointer>=SIZE_BUFFER){
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pTxBuffer->Writepointer = 0;
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}
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} else {
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TxActive = 1;
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UDR0 = c;
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}
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/* Enable the TX Interrupt again*/
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UCSR0B |= (1<<TXCIE0);
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}
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/* when data (a data frame) is to be send (written to UDR0) */
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ISR(USART0_TX_vect) {
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/* check if the read and write pointer of the send buffer are not aligned
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if not aligned -> read the next byte and write it to UDR0 register
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if aligned -> no more data to send, disable the send in progress flag */
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if(pTxBuffer->Readpointer != pTxBuffer->Writepointer)
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{
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/* writing data to the register withing the interrupt will cause a new interrupt which then will repeat till no more data is to be read from the send buffer */
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UDR0 = pTxBuffer->data[pTxBuffer->Readpointer++];
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if(pTxBuffer->Readpointer >= SIZE_BUFFER){
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pTxBuffer->Readpointer = 0;
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}
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} else {
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TxActive = 0;
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}
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}
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/*******Receiving Data*******/
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uint8_t
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uart_data_available(void) {
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uint8_t dataAvailabel = 0;
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/* Disable the RX Interrupt to prevent issues when checking if data is available */
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UCSR0B &= ~(1<<RXCIE0);
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/* check if read and write pointer are at different locations
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if yes -> data is available and can be read */
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if(pRxBuffer->Readpointer != pRxBuffer->Writepointer){
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dataAvailabel = 1;
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}
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/* Enable the RX Interrupt again*/
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UCSR0B |= (1<<RXCIE0);
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return dataAvailabel;
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}
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char
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uart_get_data(void) {
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char data = 0;
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/* Disable the RX Interrupt to prevent issues when reading out a char from the buffer */
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UCSR0B &= ~(1<<RXCIE0);
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/* check if read and write pointer are at different locations
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if yes -> data is available and can be read */
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if(pRxBuffer->Readpointer != pRxBuffer->Writepointer)
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{
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/* read a char from the buffer and increment the read pointer */
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data = pRxBuffer->data[pRxBuffer->Readpointer++];
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if(pRxBuffer->Readpointer >= SIZE_BUFFER){
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pRxBuffer->Readpointer = 0;
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}
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}
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/* Enable the RX Interrupt again*/
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UCSR0B |= (1<<RXCIE0);
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/* give back the read in character */
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return data;
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}
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/* when data (a data frame) is received */
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ISR(USART0_RX_vect) {
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uint8_t status = UCSR0A;
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uint8_t data = UDR0;
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/* check status flags if data is correctly accessible */
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if((status & ((1<<DOR0) | (1<<FE0))) == 0){
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/* Save data to buffer and increment the write pointer */
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pRxBuffer->data[pRxBuffer->Writepointer++] = data;
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if(pRxBuffer->Writepointer >= SIZE_BUFFER) {
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pRxBuffer->Writepointer = 0;
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}
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}
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} |