X-Git-Url: https://www.fi.muni.cz/~kas/git//home/kas/public_html/git/?p=heater.git;a=blobdiff_plain;f=firmware%2Fmain.c;h=ddbd2d3cf54471fd8edf97dc0dbc87ae670f3dca;hp=9a041500be8aefd19088472b2aa1ae2d8e50ca9d;hb=c1afb05fed7d9c526b606af5ff7e7883a2645038;hpb=36f60161fac194572a272bdb0239a01fcf2b801b diff --git a/firmware/main.c b/firmware/main.c index 9a04150..ddbd2d3 100644 --- a/firmware/main.c +++ b/firmware/main.c @@ -1,3 +1,51 @@ +/* + * OVERVIEW + * + * Powering up: + * Immediately after reset, we power down the entire system. + * We wake up only after the button is pressed for a sufficiently long time. + * + * Heater output: + * The heater output is driven by Timer/Counter 1 in PWM mode. + * We want to be able to measure the battery voltage both when the + * output is on, and when the output is off. So we set the T/C1 clock + * prescaler so that the T/C1 is slow enough, we enable the T/C1 interrupts + * both on compare match and on overflow. After the interrupt, we trigger + * the battery voltage measurement with ADC. + * + * ADC: + * To avoid transients, we measure each battery state (when the heater is on + * and when it is off) separately, and we drop the first few readings. + * We calculate a running average of the readings to achieve higher accuracy. + * + * Buttons: + * There are two buttons (+ and -). Any button can wake the system up from + * the power-down state. + * TODO: When the system is woken up by the "-" button, + * it starts with the minimum output power, when it is woken up by the "+" + * button, it start with the maximum output power. + * When running, the "-" button is used for decreasing the output power, + * the "+" button is for increasing it. + * When on the lowest power state, the "-" button switches the system off. + * TODO: Long "-" button press switches the system off, long "+" button + * press sets the output power to maximum. + * + * Status LED: + * When powering up by a button press, the LED goes on to provide a visual + * feedback, and is switched off after the button is released. + * TODO: After a button press, the # of blinks of the LED reflects the + * chosen output power level for some time. Afterwards, it displays + * the battery level. + * TODO: When the battery is completely exhausted, the output power is switched + * off, the LED keeps blinking for some time, and then the whole system is + * switched off to avoid deep discharge of the battery. + * + * Timing: + * The firmware is timed by the Watchdog Timer interrupt. Most of the + * processing is done from the main loop, IRQs only set various flags + * or trigger other events. + */ + #include #include #include @@ -7,30 +55,116 @@ #include "logging.h" -static unsigned char pwm = 1; +/* waking up from the power down state by a button press */ +#define WAKEUP_POLL 50 // msec +#define WAKEUP_LIMIT 5 // times WAKEUP_POLL + +/* output power levels */ +#define N_STEPS 5 +static unsigned char steps[] = { 60, 85, 121, 171, 242 }; +static unsigned char intensity = 0; // selected power level + +/* which state (output on or output off) are we measuring now */ +static volatile unsigned char adc_type, adc_drop; +static volatile uint16_t batt_on, batt_off; // measured voltage + +/* timing by WDT */ +static volatile unsigned char jiffies, next_clock_tick; + +/* ========= Analog to Digital Converter (battery voltage) ========== */ +static void adc_init() +{ + power_adc_enable(); + + ADCSRA = _BV(ADEN) // enable + | _BV(ADPS1) | _BV(ADPS0) // clk/8 = 125 kHz + | _BV(ADIE); // enable IRQ + ADMUX = _BV(REFS1) | _BV(MUX1) | _BV(MUX0); + // 1.1V reference, PB3 pin, single-ended + DIDR0 |= _BV(ADC3D); // PB3 pin as analog input +} + +static void adc_susp() +{ + ADCSRA &= ~_BV(ADEN); // disable ADC + DIDR0 &= ~_BV(ADC3D); // disable analog input on PB3 + + power_adc_disable(); +} + +static void adc_start_measurement() +{ + ADCSRA |= _BV(ADSC); +} + +ISR(ADC_vect) +{ + uint16_t adcw = ADCW; -static void timer_init() + if (adc_drop) { + adc_drop--; + ADCSRA |= _BV(ADSC); + return; + } + + // TODO: We may want to disable ADC after here to save power, + // but compared to the heater power it would be negligible, + // so don't bother with it. + if (adc_type == 0) { + if (batt_off) { + batt_off += adcw - (batt_off >> 5); + } else { + batt_off = adcw << 5; + } + } else { + if (batt_on) { + batt_on += adcw - (batt_on >> 5); + } else { + batt_on = adcw << 5; + } + } +} + +/* ===================== Timer/Counter1 for PWM ===================== */ +static void pwm_init() { power_timer1_enable(); DDRB |= _BV(PB4); - TCCR1 = _BV(CS10); // clk/1 = 1 MHz - // TCCR1 = _BV(CS11) | _BV(CS13); // clk/512 = 2 kHz + // TCCR1 = _BV(CS10); // clk/1 = 1 MHz + TCCR1 = _BV(CS11) | _BV(CS13); // clk/512 = 2 kHz GTCCR = _BV(COM1B1) | _BV(PWM1B); OCR1C = 255; - OCR1B = pwm; + OCR1B = steps[0]; + TIMSK = _BV(OCIE1B) | _BV(TOIE1); } -static void adc_init() +static void pwm_susp() { - power_adc_enable(); + TCCR1 = 0; +} - ADCSRA = _BV(ADEN) | _BV(ADPS1) | _BV(ADPS0); // clk/8 = 125 kHz - ADMUX = _BV(REFS1) | _BV(MUX1) | _BV(MUX0); // 1.1V ref., PB3 single-ended - DIDR0 = _BV(ADC3D); +ISR(TIM1_OVF_vect) +{ + adc_drop = 2; + adc_type = 1; + adc_start_measurement(); } +ISR(TIM1_COMPB_vect) +{ + adc_drop = 2; + adc_type = 0; + adc_start_measurement(); +} + +static void pwm_set(unsigned char pwm) +{ + OCR1B = pwm; +} + +/* ===================== Status LED on pin PB2 ======================= */ static void status_led_init() { DDRB |= _BV(PB2); @@ -47,6 +181,12 @@ static void status_led_off() PORTB &= ~_BV(PB2); } +static unsigned char status_led_is_on() +{ + return PORTB & _BV(PB2) ? 1 : 0; +} + +/* ================== Buttons on pin PB0 and PB1 ===================== */ static void buttons_init() { DDRB &= ~(_BV(PB0) | _BV(PB1)); // set as input @@ -73,9 +213,6 @@ static unsigned char buttons_pressed() ); } -#define WAKEUP_POLL 100 // msec -#define WAKEUP_LIMIT 5 // times WAKEUP_POLL - static unsigned char buttons_wait_for_release() { uint16_t wake_count = 0; @@ -97,8 +234,11 @@ ISR(PCINT0_vect) // empty - let it wake us from sleep, but do nothing else } +/* ==== Watchdog Timer for timing blinks and other periodic tasks ==== */ static void wdt_init() { + next_clock_tick = 0; + jiffies = 0; WDTCR = _BV(WDIE) | _BV(WDP1); // interrupt mode, 64 ms } @@ -107,11 +247,17 @@ static void wdt_susp() wdt_disable(); } +ISR(WDT_vect) { + next_clock_tick = 1; + jiffies++; +} + +/* ====== Hardware init, teardown, powering down and waking up ====== */ static void hw_setup() { power_all_disable(); - timer_init(); + pwm_init(); adc_init(); status_led_init(); wdt_init(); @@ -119,22 +265,15 @@ static void hw_setup() static void hw_suspend() { - ADCSRA &= ~_BV(ADEN); // disable ADC - TCCR1 = 0; // disable T/C 1 - - status_led_init(); + adc_susp(); + pwm_susp(); + status_led_init(); // we don't have a separate _susp() here buttons_susp(); wdt_susp(); power_all_disable(); } -static volatile unsigned char wdt_timer_fired; - -ISR(WDT_vect) { - wdt_timer_fired = 1; -} - static void power_down() { hw_suspend(); @@ -158,11 +297,11 @@ static void power_down() hw_setup(); } +/* ======== Button press detection and handling ===================== */ static void button_one_pressed() { - if (pwm > 1) { - pwm >>= 1; - OCR1B = pwm; + if (intensity > 0) { + pwm_set(steps[--intensity]); } else { power_down(); } @@ -170,9 +309,8 @@ static void button_one_pressed() static void button_two_pressed() { - if (pwm < 0x80) { - pwm <<= 1; - OCR1B = pwm; + if (intensity < N_STEPS-1) { + pwm_set(steps[++intensity]); } } @@ -207,23 +345,41 @@ static void timer_check_buttons() button_state = newstate; } +/* ============ Status LED blinking =================================== */ +static unsigned char blink_on_time, blink_off_time, n_blinks; +static unsigned char blink_counter; + +static void status_led_next_pattern() +{ + // for now, display the selected intensity + n_blinks = intensity + 1; + blink_on_time = 0; + blink_off_time = 2; + blink_counter = 10; +} + +static void timer_blink() +{ + if (blink_counter) { + blink_counter--; + } else if (status_led_is_on()) { + status_led_off(); + blink_counter = blink_off_time; + } else if (n_blinks) { + --n_blinks; + status_led_on(); + blink_counter = blink_on_time; + } else { + status_led_next_pattern(); + } +} + int main() { log_init(); power_down(); -#if 0 - ADCSRA |= _BV(ADSC); - while (!(ADCSRA & _BV(ADIF))) - ; - log_word(ADCW); - ADCSRA |= _BV(ADSC); - while (!(ADCSRA & _BV(ADIF))) - ; - log_word(ADCW); - log_flush(); -#endif sei(); // we try to be completely IRQ-driven, so just wait for IRQs here @@ -236,9 +392,12 @@ int main() sleep_cpu(); sleep_disable(); - if (wdt_timer_fired) { - wdt_timer_fired = 0; + // FIXME: Maybe handle new ADC readings as well? + if (next_clock_tick) { + next_clock_tick = 0; timer_check_buttons(); + timer_blink(); + log_flush(); } } }