diff options
Diffstat (limited to 'sw/main.cpp')
| -rw-r--r-- | sw/main.cpp | 65 |
1 files changed, 41 insertions, 24 deletions
diff --git a/sw/main.cpp b/sw/main.cpp index 2d97dec..6b7f0cf 100644 --- a/sw/main.cpp +++ b/sw/main.cpp @@ -78,11 +78,16 @@ static bool relay_state_known = false; uint32_t EEMEM stored_capacity1; uint32_t EEMEM stored_capacity2; uint32_t EEMEM stored_capacity3; -uint32_t last_store_time_seconds; +/* Store timestamp of previous execution of a subroutine. + * Subroutines scheduled in second intervals don't need to + * be stored as timer_t, to save some space and simplify + * the comparison. + */ +uint32_t last_store_time_seconds; uint32_t last_threshold_calculation_seconds; +uint32_t last_ltc2400_print_time_seconds; timer_t last_ltc2400_measure; -timer_t last_ltc2400_print_time; /* Timer at approximately 100ms. * @@ -127,6 +132,9 @@ static void flag_error(const error_type_t e); static void load_capacity_from_eeprom() { + /* Store the same value three times to make + * a majority vote to detect errors + */ uint32_t cap1 = eeprom_read_dword(&stored_capacity1); uint32_t cap2 = eeprom_read_dword(&stored_capacity2); uint32_t cap3 = eeprom_read_dword(&stored_capacity3); @@ -229,9 +237,9 @@ static void send_message(const char *message) uart_puts_P(ENDL); } -static void send_capacity(uint32_t capacity) +static void send_capacity(uint32_t capacity, const timer_t& time) { - snprintf(timestamp_buf, 15, "CAPACITY,%ld,%ld" ENDL, system_timer.get_seconds_atomic(), capacity); + snprintf(timestamp_buf, 15, "CAPACITY,%ld,%ld" ENDL, time.get_seconds_atomic(), capacity); uart_puts(timestamp_buf); } @@ -312,35 +320,44 @@ int main() else { send_message("Startup"); } + system_timer = timer_t(0, 0); - TCCR0B |= _BV(WGM02); // Set timer mode to CTC (datasheet 15.7.2) - TIMSK0 |= _BV(TOIE0); // enable overflow interrupt - OCR0A = TIMER_OVERFLOW; - TCCR0B |= _BV(CS02) | _BV(CS00); // Start timer at Fcpu/1024 /* Load capacity stored in EEPROM */ current_capacity = 0; load_capacity_from_eeprom(); - last_ltc2400_print_time = - last_ltc2400_measure = system_timer; + last_ltc2400_measure = system_timer; + last_store_time_seconds = + last_ltc2400_print_time_seconds = last_threshold_calculation_seconds = system_timer.get_seconds_atomic(); - /* Enable interrupts */ + /* Enable timer and interrupts */ + TCCR0B |= _BV(WGM02); // Set timer mode to CTC (datasheet 15.7.2) + TIMSK0 |= _BV(TOIE0); // enable overflow interrupt + OCR0A = TIMER_OVERFLOW; + TCCR0B |= _BV(CS02) | _BV(CS00); // Start timer at Fcpu/1024 sei(); // Accumulate in floating point - double accum = current_capacity; + double capacity_accum = current_capacity; /* Put the CPU to sleep */ set_sleep_mode(SLEEP_MODE_IDLE); while (true) { sleep_mode(); + /* In every loop, access the system_timer only once, so that + * every loop has a well-defined time */ const auto time_now = system_timer.get_atomic_copy(); - pins_set_status(time_now.get_microsecs_atomic() < 500000uL); + // One second blink interval + pins_set_status(time_now.seconds_ % 2 == 0); + /* EEPROM has an endurance of at least 100'000 write/erase cycles. + * (Datasheet 8.4 EEPROM Data Memory) + * Storing every five hours gives us several years of endurance. + * */ if (last_store_time_seconds + 3600 * 5 >= time_now.seconds_) { store_capacity_to_eeprom(); } @@ -364,25 +381,25 @@ int main() /* Vout - 2.5V = Ishunt * Rshunt * 20 */ const double i_shunt = (adc_voltage - 2.5) / (20.0 * R_SHUNT); - accum += i_shunt * TIMER_TICK_INTERVAL; + capacity_accum += i_shunt * TIMER_TICK_INTERVAL; - if (accum < 0) { accum = 0; } - if (accum > MAX_CAPACITY) { accum = MAX_CAPACITY; } + if (capacity_accum < 0) { capacity_accum = 0; } + if (capacity_accum > MAX_CAPACITY) { capacity_accum = MAX_CAPACITY; } - current_capacity = lrint(accum); + current_capacity = lrint(capacity_accum); } } - constexpr auto threshold_calculation_interval = 4; - if (last_threshold_calculation_seconds + threshold_calculation_interval > time_now.seconds_) { - last_threshold_calculation_seconds += threshold_calculation_interval; + constexpr auto threshold_calculation_interval_s = 4; + if (last_threshold_calculation_seconds + threshold_calculation_interval_s > time_now.seconds_) { + last_threshold_calculation_seconds += threshold_calculation_interval_s; handle_thresholds(time_now); } - const auto ltc2400_print_interval = timer_t(10, 0); - if (last_ltc2400_print_time + ltc2400_print_interval > time_now) { - last_ltc2400_print_time += ltc2400_print_interval; - send_capacity(current_capacity); + constexpr auto ltc2400_print_interval_s = 10; + if (last_ltc2400_print_time_seconds + ltc2400_print_interval_s > time_now.seconds_) { + last_ltc2400_print_time_seconds += ltc2400_print_interval_s; + send_capacity(current_capacity, time_now); } relays_handle(time_now); |