root / scout_avr / src / Atmega128rfa1.cpp @ c2b64420
History | View | Annotate | Download (2.25 KB)
| 1 | 88fb3a79 | Tom Mullins | #include "Atmega128rfa1.h" |
|---|---|---|---|
| 2 | 812788aa | Tom Mullins | #include "bom.h" |
| 3 | 88fb3a79 | Tom Mullins | |
| 4 | extern "C" |
||
| 5 | {
|
||
| 6 | #include <avr/io.h> |
||
| 7 | #include <avr/interrupt.h> |
||
| 8 | 49090532 | Tom Mullins | void __cxa_pure_virtual(void) {} |
| 9 | 88fb3a79 | Tom Mullins | } |
| 10 | |||
| 11 | 812788aa | Tom Mullins | #define T0_KHZ 76 |
| 12 | #define T0_OCR (F_CPU / 1000 / T0_KHZ) // 210 ticks |
||
| 13 | #define T0_ERROR (F_CPU / 1000 - T0_OCR*T0_KHZ) // 40 ticks/ms |
||
| 14 | |||
| 15 | unsigned char t0_count, t0_error; |
||
| 16 | 88fb3a79 | Tom Mullins | unsigned long millis; |
| 17 | |||
| 18 | aadf0a75 | Tom Mullins | int rx_start, rx_end;
|
| 19 | 20f94878 | Tom Mullins | char rx_buffer[RX_BUFFER_SIZE];
|
| 20 | |||
| 21 | 88fb3a79 | Tom Mullins | Atmega128rfa1::Atmega128rfa1() |
| 22 | {
|
||
| 23 | } |
||
| 24 | |||
| 25 | ISR(TIMER0_COMPA_vect) |
||
| 26 | {
|
||
| 27 | 812788aa | Tom Mullins | bom_isr(); |
| 28 | |||
| 29 | // F_CPU = T0_OCR * T0_KHZ + T0_ERROR
|
||
| 30 | // every millisecond, accumulate T0_ERROR, and when it reaches T0_OCR skip
|
||
| 31 | // one iteration
|
||
| 32 | t0_count++; |
||
| 33 | if (t0_count >= T0_KHZ) {
|
||
| 34 | t0_error += T0_ERROR; |
||
| 35 | if (t0_error < T0_OCR) {
|
||
| 36 | t0_count = 0;
|
||
| 37 | } else {
|
||
| 38 | t0_count = -1;
|
||
| 39 | t0_error -= T0_OCR; |
||
| 40 | } |
||
| 41 | millis++; |
||
| 42 | } |
||
| 43 | 88fb3a79 | Tom Mullins | } |
| 44 | |||
| 45 | 807483bf | Tom Mullins | ISR(USART0_RX_vect) |
| 46 | 20f94878 | Tom Mullins | {
|
| 47 | char data = UDR0;
|
||
| 48 | aadf0a75 | Tom Mullins | int new_end = rx_end+1; |
| 49 | if (new_end == RX_BUFFER_SIZE) {
|
||
| 50 | new_end = 0;
|
||
| 51 | } |
||
| 52 | if (new_end == rx_start)
|
||
| 53 | 20f94878 | Tom Mullins | {
|
| 54 | // TODO warn of buffer overflow?
|
||
| 55 | } |
||
| 56 | else
|
||
| 57 | {
|
||
| 58 | rx_buffer[rx_end] = data; |
||
| 59 | aadf0a75 | Tom Mullins | rx_end = new_end; |
| 60 | 20f94878 | Tom Mullins | } |
| 61 | } |
||
| 62 | |||
| 63 | 88fb3a79 | Tom Mullins | void Atmega128rfa1::init()
|
| 64 | {
|
||
| 65 | // === init serial ===
|
||
| 66 | 49090532 | Tom Mullins | // baud = F_CPU / (16 (UBRR + 1))
|
| 67 | 1c3c96ce | Tom Mullins | uint16_t ubrr = F_CPU / 16 / BAUD_RATE - 1; |
| 68 | 49090532 | Tom Mullins | UBRR0H = ubrr >> 8;
|
| 69 | UBRR0L = ubrr; |
||
| 70 | 88fb3a79 | Tom Mullins | // UMSEL0 = 0, asynchronous usart
|
| 71 | // UPM0 = 0, parity check disabled
|
||
| 72 | // USBS0 = 0, 1 stop bit
|
||
| 73 | // UCSZ0 = 3, 8-bit
|
||
| 74 | 20f94878 | Tom Mullins | UCSR0B = _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0); |
| 75 | 88fb3a79 | Tom Mullins | UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); |
| 76 | |||
| 77 | // === init time ===
|
||
| 78 | // COM0x = 0, pin OC0x not used
|
||
| 79 | // WGM0 = 2, clear timer on compare match, TOP = OCRA
|
||
| 80 | 812788aa | Tom Mullins | // CS0 = 1, no prescaler
|
| 81 | 88fb3a79 | Tom Mullins | TCCR0A = _BV(WGM01); |
| 82 | 812788aa | Tom Mullins | TCCR0B = _BV(CS00); |
| 83 | 88fb3a79 | Tom Mullins | // enable interrupt on compare match A
|
| 84 | TIMSK0 = _BV(OCIE0A); |
||
| 85 | 812788aa | Tom Mullins | OCR0A = T0_OCR; |
| 86 | 88fb3a79 | Tom Mullins | millis = 0;
|
| 87 | 20f94878 | Tom Mullins | |
| 88 | sei(); |
||
| 89 | 88fb3a79 | Tom Mullins | } |
| 90 | |||
| 91 | int Atmega128rfa1::read()
|
||
| 92 | {
|
||
| 93 | aadf0a75 | Tom Mullins | int ret;
|
| 94 | cf115e3d | Tom Mullins | cli(); |
| 95 | 20f94878 | Tom Mullins | if (rx_start == rx_end)
|
| 96 | aadf0a75 | Tom Mullins | ret = -1;
|
| 97 | 20f94878 | Tom Mullins | else
|
| 98 | {
|
||
| 99 | aadf0a75 | Tom Mullins | ret = rx_buffer[rx_start]; |
| 100 | 20f94878 | Tom Mullins | rx_start++; |
| 101 | if (rx_start == RX_BUFFER_SIZE)
|
||
| 102 | rx_start = 0;
|
||
| 103 | } |
||
| 104 | cf115e3d | Tom Mullins | sei(); |
| 105 | aadf0a75 | Tom Mullins | return ret;
|
| 106 | 88fb3a79 | Tom Mullins | } |
| 107 | |||
| 108 | void Atmega128rfa1::write(uint8_t* data, int length) |
||
| 109 | {
|
||
| 110 | // TODO make this non-blocking with a tx buffer
|
||
| 111 | int i;
|
||
| 112 | for (i = 0; i < length; i++) |
||
| 113 | {
|
||
| 114 | while (!(UCSR0A & _BV(UDRE0)));
|
||
| 115 | UDR0 = data[i]; |
||
| 116 | } |
||
| 117 | } |
||
| 118 | |||
| 119 | unsigned long Atmega128rfa1::time() |
||
| 120 | {
|
||
| 121 | unsigned long ret; |
||
| 122 | cli(); |
||
| 123 | ret = millis; |
||
| 124 | sei(); |
||
| 125 | return ret;
|
||
| 126 | } |