From 0ed054882561be8e1282c4e2a3d626294fc2420b Mon Sep 17 00:00:00 2001 From: "Jan \"Yenya\" Kasprzak" Date: Fri, 31 Jan 2014 17:10:41 +0100 Subject: [PATCH] power output calculation --- firmware/main.c | 83 +++++++++++++++++++++++++++++++++++++------------ 1 file changed, 63 insertions(+), 20 deletions(-) diff --git a/firmware/main.c b/firmware/main.c index 5c9a566..d35fb21 100644 --- a/firmware/main.c +++ b/firmware/main.c @@ -59,14 +59,6 @@ #define WAKEUP_POLL 50 // msec #define WAKEUP_LIMIT 5 // times WAKEUP_POLL -/* output power levels */ -#define N_POWER_LEVELS 5 -static unsigned char power_levels[N_POWER_LEVELS] = { - -}; - -static unsigned char power_level = 0; // selected power level - /* which state (output on or output off) are we measuring now */ static volatile unsigned char adc_type, adc_drop; #define ADC_RUNAVG_SHIFT 5 // running average shift on batt_on, batt_off @@ -82,12 +74,38 @@ static volatile uint16_t batt_on, batt_off; // measured voltage #define MV_TO_ADC8(mV) ((unsigned char)(((uint32_t)(1UL << ADC_RUNAVG_SHIFT) \ * (1024UL * (mV)) \ / (6UL * ADC_1100MV_VALUE)) >> 8)) -#define BATT_N_LEVELS 3 -static unsigned char batt_levels[BATT_N_LEVELS] = { - MV_TO_ADC8(3500), +static unsigned char batt_levels[] = { + MV_TO_ADC8(3350), MV_TO_ADC8(3700), MV_TO_ADC8(3900), }; +#define BATT_N_LEVELS (sizeof(batt_levels) / sizeof(batt_levels[0])) + +/* output power and PWM calculation */ +#define PWM_TOP 255 +#define PWM_MAX (PWM_TOP - 8) // to allow for ADC "batt_off" measurements + +/* + * The values in power_levels[] array are voltages at which the load + * would give the expected power (we don't have sqrt() function, + * so we cannot use mW values directly. They can be calculated as + * voltage[V] = sqrt(load_resistance[Ohm] * expected_power[W]) + * or + * voltage[mV] = sqrt(load_resistance[mOhm] * expected_power[mW]) + * + * I use 1.25 W as minimum power, each step is sqrt(2)*previous_step, + * so the 5th step is 5 W. + */ +static unsigned char power_levels[] = { + MV_TO_ADC8(1581), // 1250 mW for 2 Ohm load + MV_TO_ADC8(1880), // 1768 mW for 2 Ohm load + MV_TO_ADC8(2236), // 2500 mW for 2 Ohm load + MV_TO_ADC8(2659), // 3536 mW for 2 Ohm load + MV_TO_ADC8(3162), // 5000 mW for 2 Ohm load +}; +#define N_POWER_LEVELS (sizeof(power_levels) / sizeof(power_levels[0])) + +static unsigned char power_level = 0; // selected power level /* timing by WDT */ static volatile unsigned char jiffies, next_clock_tick; @@ -160,7 +178,7 @@ static void pwm_init() // TCCR1 = _BV(CS10); // clk/1 = 1 MHz TCCR1 = _BV(CS11) | _BV(CS13); // clk/512 = 2 kHz GTCCR = _BV(COM1B1) | _BV(PWM1B); - OCR1C = 255; + OCR1C = PWM_TOP; // OCR1B = steps[0]; OCR1B = 0; TIMSK = _BV(OCIE1B) | _BV(TOIE1); @@ -402,8 +420,8 @@ static void status_led_next_pattern() { // for now, display the selected intensity - n_blinks = power_level + 1; - // n_blinks = battery_level() + 1; + // n_blinks = power_level + 1; + n_blinks = battery_level() + 1; blink_on_time = 0; blink_off_time = 2; blink_counter = 10; @@ -425,6 +443,33 @@ static void timer_blink() } } +static void calculate_power_level() +{ + uint32_t pwm; + unsigned char batt_on8; + + if (battery_level() == 0 || batt_on == 0) { + pwm_set(0); + // TODO power_down() after some time + return; + } + + batt_on8 = batt_on >> 8; + + pwm = (uint32_t)PWM_TOP * power_levels[power_level] + * power_levels[power_level]; + pwm /= (uint32_t)batt_on8 * batt_on8; + + if (pwm > PWM_MAX) + pwm = PWM_MAX; + + log_byte(0x10 + power_level); + log_byte(batt_on8); + log_byte(pwm & 0xFF); + + pwm_set(pwm); +} + int main() { log_init(); @@ -435,6 +480,9 @@ int main() log_word(batt_levels[2]); log_flush(); #endif + log_byte(power_levels[0]); + log_byte(power_levels[4]); + log_flush(); power_down(); @@ -459,12 +507,7 @@ int main() timer_check_buttons(); if ((jiffies & 0x0F) == 0) { - unsigned char i; - - for (i = 0; i < BATT_N_LEVELS; i++) - if (batt_levels[i] > batt_off) - break; - + calculate_power_level(); #if 0 log_byte(0xcc); log_byte(i); -- 2.39.3