1 | #include "uart.h"
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2 | #include <avr/io.h>
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3 | #include <avr/pgmspace.h>
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4 | #include <avr/interrupt.h>
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5 |
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6 | #define SEND_BUF_BITS 4
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7 | #define SEND_BUF_SIZE (1<<SEND_BUF_BITS)
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8 | #define SEND_BUF_MASK (SEND_BUF_SIZE-1)
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9 | #define RECV_BUF_BITS 2
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10 | #define RECV_BUF_SIZE (1<<RECV_BUF_BITS)
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11 | #define RECV_BUF_MASK (RECV_BUF_SIZE-1)
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12 |
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13 |
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14 | static volatile uint8_t send_buf_start;
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15 | static uint8_t send_buf_end;
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16 | static char send_buf[SEND_BUF_SIZE];
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17 |
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18 | static uint8_t recv_buf_start;
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19 | static volatile uint8_t recv_buf_end;
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20 | static char recv_buf[RECV_BUF_SIZE];
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21 |
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22 |
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23 | void uart_init(uint16_t baud) {
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24 | // ifdef ATTINY...
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25 | UCSRA = _BV(U2X);
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26 | UCSRB = _BV(TXEN) | _BV(RXEN) | _BV(RXCIE); //UART TX+RX einschalten
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27 | UCSRC |= _BV(UCSZ0)|_BV(UCSZ1); //Asynchron 8N1
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28 | UBRRH=(uint8_t)((baud)>>8);
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29 | UBRRL=(uint8_t)(baud);
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30 |
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31 | send_buf_start=0;
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32 | send_buf_end=0;
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33 | recv_buf_start=0;
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34 | recv_buf_end=0;
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35 | }
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36 | void uart_putc(char c)
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37 | {
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38 | uint8_t next_pos=(send_buf_end+1)&SEND_BUF_MASK;
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39 |
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40 | // wait till we got space in buffer
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41 | while ((SREG & _BV(SREG_I)) && (next_pos == send_buf_start));
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42 |
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43 | if (next_pos == send_buf_start) {
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44 | // Interrupts are disabled and buffer is full. we loose this char.
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45 | return;
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46 | }
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47 |
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48 | send_buf[send_buf_end]=c;
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49 |
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50 | send_buf_end=next_pos;
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51 |
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52 | // Enable UDR interrupt. will immediatly call ISR if UDRE is set.
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53 | UCSRB = _BV(TXEN) | _BV(RXEN) | _BV(UDRIE) | _BV(RXCIE);
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54 | }
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55 |
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56 | void uart_write(const char * c) {
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57 | while (*c) {
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58 | uart_putc(*c++);
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59 | }
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60 | }
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61 | void uart_write_P(const char * c) {
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62 | char ch;
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63 | do {
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64 | ch=pgm_read_byte(c++);
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65 | if (!ch) return;
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66 | uart_putc(ch);
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67 | } while(1);
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68 | }
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69 | char uart_getc(void) {
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70 | // Wait till byte in buffer
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71 | while(recv_buf_start == recv_buf_end);
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72 | char x=recv_buf[recv_buf_start++];
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73 | recv_buf_start &=RECV_BUF_MASK;
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74 | return x;
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75 | }
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76 |
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77 | uint8_t uart_recv_buf_size(void) {
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78 | if (recv_buf_end >= recv_buf_start) {
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79 | return recv_buf_end - recv_buf_start;
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80 | }
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81 | return recv_buf_end + RECV_BUF_SIZE - recv_buf_start;
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82 | }
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83 |
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84 | uint8_t uart_send_buf_size(void) {
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85 | if (send_buf_end >= send_buf_start) {
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86 | return send_buf_end - send_buf_start;
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87 | }
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88 | return send_buf_end + SEND_BUF_SIZE - send_buf_start;
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89 | }
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90 | ISR(USART_RX_vect) {
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91 | recv_buf[recv_buf_end]=UDR;
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92 |
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93 | recv_buf_end=(recv_buf_end+1)&RECV_BUF_MASK;
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94 |
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95 | if (recv_buf_end == recv_buf_start) {
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96 | // Overflow! drop the first byte of the recv_buf.
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97 | recv_buf_start=(recv_buf_start+1)&RECV_BUF_MASK;
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98 | }
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99 | }
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100 |
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101 | ISR(USART_UDRE_vect) {
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102 | if (send_buf_end == send_buf_start) {
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103 | // No data to send, disable ISR.
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104 | UCSRB = _BV(TXEN) | _BV(RXEN) | _BV(RXCIE);
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105 | } else {
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106 | UDR=send_buf[send_buf_start++];
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107 | send_buf_start &=SEND_BUF_MASK;
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108 | }
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109 | }
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