From c1afb05fed7d9c526b606af5ff7e7883a2645038 Mon Sep 17 00:00:00 2001 From: "Jan \"Yenya\" Kasprzak" Date: Fri, 31 Jan 2014 11:28:32 +0100 Subject: [PATCH] Code cleanup and overview --- firmware/main.c | 211 ++++++++++++++++++++++++++++++++++-------------- 1 file changed, 149 insertions(+), 62 deletions(-) diff --git a/firmware/main.c b/firmware/main.c index fcb7426..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 @@ -7,56 +55,48 @@ #include "logging.h" +/* 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; - -static void timer_init() -{ - power_timer1_enable(); - - DDRB |= _BV(PB4); +static unsigned char intensity = 0; // selected power level - // TCCR1 = _BV(CS10); // clk/1 = 1 MHz - TCCR1 = _BV(CS11) | _BV(CS13); // clk/512 = 2 kHz - GTCCR = _BV(COM1B1) | _BV(PWM1B); - OCR1C = 255; - OCR1B = steps[0]; - TIMSK = _BV(OCIE1B) | _BV(TOIE1); -} +/* 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 -volatile unsigned char adc_type, adc_drop; +/* timing by WDT */ +static volatile unsigned char jiffies, next_clock_tick; -ISR(TIM1_OVF_vect) +/* ========= Analog to Digital Converter (battery voltage) ========== */ +static void adc_init() { - adc_drop = 2; - adc_type = 1; - ADCSRA |= _BV(ADSC); -} + power_adc_enable(); -ISR(TIM1_COMPB_vect) -{ - adc_drop = 2; - adc_type = 0; - ADCSRA |= _BV(ADSC); + 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 set_pwm(unsigned char pwm) +static void adc_susp() { - OCR1B = pwm; + ADCSRA &= ~_BV(ADEN); // disable ADC + DIDR0 &= ~_BV(ADC3D); // disable analog input on PB3 + + power_adc_disable(); } -static void adc_init() +static void adc_start_measurement() { - power_adc_enable(); - - ADCSRA = _BV(ADEN) | _BV(ADPS1) | _BV(ADPS0) | _BV(ADIE); // clk/8 = 125 kHz - ADMUX = _BV(REFS1) | _BV(MUX1) | _BV(MUX0); // 1.1V ref., PB3 single-ended - DIDR0 = _BV(ADC3D); + ADCSRA |= _BV(ADSC); } -volatile uint16_t batt_on, batt_off; - ISR(ADC_vect) { uint16_t adcw = ADCW; @@ -67,6 +107,9 @@ ISR(ADC_vect) 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); @@ -82,6 +125,46 @@ ISR(ADC_vect) } } +/* ===================== 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 + GTCCR = _BV(COM1B1) | _BV(PWM1B); + OCR1C = 255; + OCR1B = steps[0]; + TIMSK = _BV(OCIE1B) | _BV(TOIE1); +} + +static void pwm_susp() +{ + TCCR1 = 0; +} + +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); @@ -103,6 +186,7 @@ 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 @@ -129,9 +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; @@ -153,8 +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 } @@ -163,11 +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(); @@ -175,22 +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(); @@ -214,10 +297,11 @@ static void power_down() hw_setup(); } +/* ======== Button press detection and handling ===================== */ static void button_one_pressed() { if (intensity > 0) { - set_pwm(steps[--intensity]); + pwm_set(steps[--intensity]); } else { power_down(); } @@ -226,7 +310,7 @@ static void button_one_pressed() static void button_two_pressed() { if (intensity < N_STEPS-1) { - set_pwm(steps[++intensity]); + pwm_set(steps[++intensity]); } } @@ -261,9 +345,19 @@ 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) { @@ -276,15 +370,7 @@ static void timer_blink() status_led_on(); blink_counter = blink_on_time; } else { - n_blinks = intensity + 1; - blink_on_time = 0; - blink_off_time = 2; - blink_counter = 10; -#if 0 - log_byte(0xbb); - log_byte(batt_on >> 7); - log_byte(batt_off >> 7); -#endif + status_led_next_pattern(); } } @@ -306,8 +392,9 @@ 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(); -- 2.39.3