root / scout_avr / src / Atmega128rfa1.cpp @ fd73d758
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| 1 | 88fb3a79 | Tom Mullins | #include "Atmega128rfa1.h" |
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| 2 | 812788aa | Tom Mullins | #include "bom.h" |
| 3 | 88fb3a79 | Tom Mullins | |
| 4 | extern "C" |
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| 5 | {
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| 6 | #include <avr/io.h> |
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| 7 | #include <avr/interrupt.h> |
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| 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 |
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| 13 | #define T0_ERROR (F_CPU / 1000 - T0_OCR*T0_KHZ) // 40 ticks/ms |
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| 14 | |||
| 15 | unsigned char t0_count, t0_error; |
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| 16 | 88fb3a79 | Tom Mullins | unsigned long millis; |
| 17 | |||
| 18 | 20f94878 | Tom Mullins | int rx_start = 0, rx_end = 0; |
| 19 | char rx_buffer[RX_BUFFER_SIZE];
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| 20 | |||
| 21 | 88fb3a79 | Tom Mullins | Atmega128rfa1::Atmega128rfa1() |
| 22 | {
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| 23 | } |
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| 24 | |||
| 25 | ISR(TIMER0_COMPA_vect) |
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| 26 | {
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| 27 | 812788aa | Tom Mullins | bom_isr(); |
| 28 | |||
| 29 | // F_CPU = T0_OCR * T0_KHZ + T0_ERROR
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| 30 | // every millisecond, accumulate T0_ERROR, and when it reaches T0_OCR skip
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| 31 | // one iteration
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| 32 | t0_count++; |
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| 33 | if (t0_count >= T0_KHZ) {
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| 34 | t0_error += T0_ERROR; |
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| 35 | if (t0_error < T0_OCR) {
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| 36 | t0_count = 0;
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| 37 | } else {
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| 38 | t0_count = -1;
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| 39 | t0_error -= T0_OCR; |
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| 40 | } |
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| 41 | millis++; |
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| 42 | } |
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| 43 | 88fb3a79 | Tom Mullins | } |
| 44 | |||
| 45 | 807483bf | Tom Mullins | ISR(USART0_RX_vect) |
| 46 | 20f94878 | Tom Mullins | {
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| 47 | char data = UDR0;
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| 48 | cf115e3d | Tom Mullins | if (rx_end == rx_start-1 || (rx_start == 0 && rx_end == RX_BUFFER_SIZE-1)) |
| 49 | 20f94878 | Tom Mullins | {
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| 50 | // TODO warn of buffer overflow?
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| 51 | } |
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| 52 | else
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| 53 | {
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| 54 | rx_buffer[rx_end] = data; |
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| 55 | rx_end++; |
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| 56 | if (rx_end == RX_BUFFER_SIZE)
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| 57 | rx_end = 0;
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| 58 | } |
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| 59 | } |
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| 60 | |||
| 61 | 88fb3a79 | Tom Mullins | void Atmega128rfa1::init()
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| 62 | {
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| 63 | // === init serial ===
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| 64 | 49090532 | Tom Mullins | // baud = F_CPU / (16 (UBRR + 1))
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| 65 | 1c3c96ce | Tom Mullins | uint16_t ubrr = F_CPU / 16 / BAUD_RATE - 1; |
| 66 | 49090532 | Tom Mullins | UBRR0H = ubrr >> 8;
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| 67 | UBRR0L = ubrr; |
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| 68 | 88fb3a79 | Tom Mullins | // UMSEL0 = 0, asynchronous usart
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| 69 | // UPM0 = 0, parity check disabled
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| 70 | // USBS0 = 0, 1 stop bit
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| 71 | // UCSZ0 = 3, 8-bit
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| 72 | 20f94878 | Tom Mullins | UCSR0B = _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0); |
| 73 | 88fb3a79 | Tom Mullins | UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); |
| 74 | |||
| 75 | // === init time ===
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| 76 | // COM0x = 0, pin OC0x not used
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| 77 | // WGM0 = 2, clear timer on compare match, TOP = OCRA
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| 78 | 812788aa | Tom Mullins | // CS0 = 1, no prescaler
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| 79 | 88fb3a79 | Tom Mullins | TCCR0A = _BV(WGM01); |
| 80 | 812788aa | Tom Mullins | TCCR0B = _BV(CS00); |
| 81 | 88fb3a79 | Tom Mullins | // enable interrupt on compare match A
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| 82 | TIMSK0 = _BV(OCIE0A); |
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| 83 | 812788aa | Tom Mullins | OCR0A = T0_OCR; |
| 84 | 88fb3a79 | Tom Mullins | millis = 0;
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| 85 | 20f94878 | Tom Mullins | |
| 86 | sei(); |
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| 87 | 88fb3a79 | Tom Mullins | } |
| 88 | |||
| 89 | int Atmega128rfa1::read()
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| 90 | {
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| 91 | cf115e3d | Tom Mullins | cli(); |
| 92 | 20f94878 | Tom Mullins | if (rx_start == rx_end)
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| 93 | return -1; |
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| 94 | else
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| 95 | {
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| 96 | int ret = rx_buffer[rx_start];
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| 97 | rx_start++; |
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| 98 | if (rx_start == RX_BUFFER_SIZE)
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| 99 | rx_start = 0;
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| 100 | return ret;
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| 101 | } |
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| 102 | cf115e3d | Tom Mullins | sei(); |
| 103 | 88fb3a79 | Tom Mullins | } |
| 104 | |||
| 105 | void Atmega128rfa1::write(uint8_t* data, int length) |
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| 106 | {
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| 107 | // TODO make this non-blocking with a tx buffer
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| 108 | int i;
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| 109 | for (i = 0; i < length; i++) |
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| 110 | {
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| 111 | while (!(UCSR0A & _BV(UDRE0)));
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| 112 | UDR0 = data[i]; |
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| 113 | } |
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| 114 | } |
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| 115 | |||
| 116 | unsigned long Atmega128rfa1::time() |
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| 117 | {
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| 118 | unsigned long ret; |
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| 119 | cli(); |
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| 120 | ret = millis; |
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| 121 | sei(); |
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| 122 | return ret;
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| 123 | } |