firmware/main.c

   1 #include <avr/interrupt.h>
   2 #include <avr/io.h>
   3 #include <avr/power.h>
   4 #include <avr/sleep.h>
   5 #include <avr/wdt.h>
   6 #include <util/delay.h>
   7
   8 #include "logging.h"
   9
  10 static unsigned char pwm = 1;
  11
  12 static void timer_init()
  13 {
  14         power_timer1_enable();
  15
  16         DDRB |= _BV(PB4);
  17
  18         TCCR1 = _BV(CS10); // clk/1 = 1 MHz
  19         // TCCR1 = _BV(CS11) | _BV(CS13); // clk/512 = 2 kHz
  20         GTCCR = _BV(COM1B1) | _BV(PWM1B);
  21         OCR1C = 255;
  22         OCR1B = pwm;
  23 }
  24
  25 static void adc_init()
  26 {
  27         power_adc_enable();
  28
  29         ADCSRA = _BV(ADEN) | _BV(ADPS1) | _BV(ADPS0); // clk/8 = 125 kHz
  30         ADMUX = _BV(REFS1) | _BV(MUX1) | _BV(MUX0); // 1.1V ref., PB3 single-ended
  31         DIDR0 = _BV(ADC3D);
  32 }
  33
  34 static void status_led_init()
  35 {
  36         DDRB |= _BV(PB2);
  37         PORTB &= ~_BV(PB2);
  38 }
  39
  40 static void status_led_on()
  41 {
  42         PORTB |= _BV(PB2);
  43 }
  44
  45 static void status_led_off()
  46 {
  47         PORTB &= ~_BV(PB2);
  48 }
  49
  50 static void buttons_init()
  51 {
  52         DDRB &= ~(_BV(PB0) | _BV(PB1)); // set as input
  53         PORTB |= _BV(PB0) | _BV(PB1);   // internal pull-up
  54
  55         GIMSK &= ~_BV(PCIE); // disable pin-change IRQs
  56         PCMSK = 0; // disable pin-change IRQs on all pins of port B
  57 }
  58
  59 static void buttons_susp()
  60 {
  61         buttons_init();
  62
  63         GIMSK |= _BV(PCIE);
  64         PCMSK |= _BV(PCINT0) | _BV(PCINT1);
  65 }
  66
  67 static unsigned char buttons_pressed()
  68 {
  69         return (
  70                 (PINB & _BV(PB0) ? 0 : 1)
  71                 |
  72                 (PINB & _BV(PB1) ? 0 : 2)
  73         );
  74 }
  75
  76 #define WAKEUP_POLL 100 // msec
  77 #define WAKEUP_LIMIT 5  // times WAKEUP_POLL
  78
  79 static unsigned char buttons_wait_for_release()
  80 {
  81         uint16_t wake_count = 0;
  82
  83         do {
  84                 if (++wake_count > WAKEUP_LIMIT)
  85                         status_led_on(); // inform the user
  86
  87                 _delay_ms(WAKEUP_POLL);
  88         } while (buttons_pressed());
  89
  90         status_led_off();
  91
  92         return wake_count > WAKEUP_LIMIT;
  93 }
  94
  95 ISR(PCINT0_vect)
  96 {
  97         // empty - let it wake us from sleep, but do nothing else
  98 }
  99
 100 static void wdt_init()
 101 {
 102         WDTCR = _BV(WDIE) | _BV(WDP1); // interrupt mode, 64 ms
 103 }
 104
 105 static void wdt_susp()
 106 {
 107         wdt_disable();
 108 }
 109
 110 static void hw_setup()
 111 {
 112         power_all_disable();
 113
 114         timer_init();
 115         adc_init();
 116         status_led_init();
 117         wdt_init();
 118 }
 119
 120 static void hw_suspend()
 121 {
 122         ADCSRA &= ~_BV(ADEN); // disable ADC
 123         TCCR1 = 0; // disable T/C 1
 124
 125         status_led_init();
 126         buttons_susp();
 127         wdt_susp();
 128
 129         power_all_disable();
 130 }
 131
 132 static volatile unsigned char wdt_timer_fired;
 133
 134 ISR(WDT_vect) {
 135         wdt_timer_fired = 1;
 136 }
 137
 138 static void power_down()
 139 {
 140         hw_suspend();
 141
 142         do {
 143                 // G'night
 144                 set_sleep_mode(SLEEP_MODE_PWR_DOWN);
 145                 sleep_enable();
 146                 sleep_bod_disable();
 147                 sei();
 148                 sleep_cpu();
 149
 150                 // G'morning
 151                 cli();
 152                 sleep_disable();
 153
 154                 // allow wakeup by long button-press only
 155         } while (!buttons_wait_for_release());
 156
 157         // OK, wake up now
 158         hw_setup();
 159 }
 160
 161 static void button_one_pressed()
 162 {
 163         if (pwm > 1) {
 164                 pwm >>= 1;
 165                 OCR1B = pwm;
 166         } else {
 167                 power_down();
 168         }
 169 }
 170
 171 static void button_two_pressed()
 172 {
 173         if (pwm < 0x80) {
 174                 pwm <<= 1;
 175                 OCR1B = pwm;
 176         }
 177 }
 178
 179 static unsigned char button_state, button_state_time;
 180
 181 static void timer_check_buttons()
 182 {
 183         unsigned char newstate = buttons_pressed();
 184
 185         if (newstate == button_state) {
 186                 if (newstate && button_state_time < 4)
 187                         ++button_state_time;
 188                 return;
 189         }
 190
 191         if (newstate) {
 192                 button_state = newstate;
 193                 button_state_time = 0;
 194                 return;
 195         }
 196
 197         // just released
 198         switch (button_state) {
 199         case 1: button_one_pressed();
 200                 break;
 201         case 2: button_two_pressed();
 202                 break;
 203         default: // ignore when both are preseed
 204                 break;
 205         }
 206
 207         button_state = newstate;
 208 }
 209
 210 int main()
 211 {
 212         log_init();
 213
 214         power_down();
 215
 216 #if 0
 217         ADCSRA |= _BV(ADSC);
 218         while (!(ADCSRA & _BV(ADIF)))
 219                 ;
 220         log_word(ADCW);
 221         ADCSRA |= _BV(ADSC);
 222         while (!(ADCSRA & _BV(ADIF)))
 223                 ;
 224         log_word(ADCW);
 225         log_flush();
 226 #endif
 227         sei();
 228
 229         // we try to be completely IRQ-driven, so just wait for IRQs here
 230         while(1) {
 231                 cli();
 232                 set_sleep_mode(SLEEP_MODE_IDLE);
 233                 sleep_enable();
 234                 // keep BOD active, no sleep_bod_disable();
 235                 sei();
 236                 sleep_cpu();
 237                 sleep_disable();
 238
 239                 if (wdt_timer_fired) {
 240                         wdt_timer_fired = 0;
 241                         timer_check_buttons();
 242                 }
 243         }
 244 }