Author: mark9064 <30447455+mark9064@users.noreply.github.com>
aod: PPI/RTC-based backlight brightness
src/components/brightness/BrightnessController.cpp | 124 ++++++++++++++- src/components/brightness/BrightnessController.h | 24 ++ src/displayapp/DisplayApp.cpp | 10 + src/systemtask/SystemTask.cpp | 4
diff --git a/src/components/brightness/BrightnessController.cpp b/src/components/brightness/BrightnessController.cpp index 0392158cbc1119c1990ac78757a5076c4eeaf81b..4d1eba6ac588420b2025b9489385eeab1572dc90 100644 --- a/src/components/brightness/BrightnessController.cpp +++ b/src/components/brightness/BrightnessController.cpp @@ -2,38 +2,138 @@ #include "components/brightness/BrightnessController.h" #include <hal/nrf_gpio.h> #include "displayapp/screens/Symbols.h" #include "drivers/PinMap.h" +#include <libraries/delay/nrf_delay.h> using namespace Pinetime::Controllers; +namespace { + // reinterpret_cast is not constexpr so this is the best we can do + static NRF_RTC_Type* const RTC = reinterpret_cast<NRF_RTC_Type*>(NRF_RTC2_BASE); +} + void BrightnessController::Init() { nrf_gpio_cfg_output(PinMap::LcdBacklightLow); nrf_gpio_cfg_output(PinMap::LcdBacklightMedium); nrf_gpio_cfg_output(PinMap::LcdBacklightHigh); + + nrf_gpio_pin_clear(PinMap::LcdBacklightLow); + nrf_gpio_pin_clear(PinMap::LcdBacklightMedium); + nrf_gpio_pin_clear(PinMap::LcdBacklightHigh); + + static_assert(timerFrequency == 32768, "Change the prescaler below"); + RTC->PRESCALER = 0; + // CC1 switches the backlight on (pin transitions from high to low) and resets the counter to 0 + RTC->CC[1] = timerPeriod; + // Enable compare events for CC0,CC1 + RTC->EVTEN = 0b0000'0000'0000'0011'0000'0000'0000'0000; + // Disable all interrupts + RTC->INTENCLR = 0b0000'0000'0000'1111'0000'0000'0000'0011; Set(level); } +void BrightnessController::ApplyBrightness(uint16_t rawBrightness) { + // The classic off, low, medium, high brightnesses are at {0, timerPeriod, timerPeriod*2, timerPeriod*3} + // These brightness levels do not use PWM: they only set/clear the corresponding pins + // Any brightness level between the above levels is achieved with efficient RTC based PWM on the next pin up + // E.g 2.5*timerPeriod corresponds to medium brightness with 50% PWM on the high pin + // Note: Raw brightness does not necessarily correspond to a linear perceived brightness + + uint8_t pin; + if (rawBrightness > 2 * timerPeriod) { + rawBrightness -= 2 * timerPeriod; + pin = PinMap::LcdBacklightHigh; + } else if (rawBrightness > timerPeriod) { + rawBrightness -= timerPeriod; + pin = PinMap::LcdBacklightMedium; + } else { + pin = PinMap::LcdBacklightLow; + } + if (rawBrightness == timerPeriod || rawBrightness == 0) { + if (lastPin != UNSET) { + RTC->TASKS_STOP = 1; + nrf_delay_us(rtcStopTime); + nrf_ppi_channel_disable(ppiBacklightOff); + nrf_ppi_channel_disable(ppiBacklightOn); + nrfx_gpiote_out_uninit(lastPin); + nrf_gpio_cfg_output(lastPin); + } + lastPin = UNSET; + if (rawBrightness == 0) { + nrf_gpio_pin_set(pin); + } else { + nrf_gpio_pin_clear(pin); + } + } else { + // If the pin on which we are doing PWM is changing + // Disable old PWM channel (if exists) and set up new one + if (lastPin != pin) { + if (lastPin != UNSET) { + RTC->TASKS_STOP = 1; + nrf_delay_us(rtcStopTime); + nrf_ppi_channel_disable(ppiBacklightOff); + nrf_ppi_channel_disable(ppiBacklightOn); + nrfx_gpiote_out_uninit(lastPin); + nrf_gpio_cfg_output(lastPin); + } + nrfx_gpiote_out_config_t gpioteCfg = {.action = NRF_GPIOTE_POLARITY_TOGGLE, + .init_state = NRF_GPIOTE_INITIAL_VALUE_LOW, + .task_pin = true}; + APP_ERROR_CHECK(nrfx_gpiote_out_init(pin, &gpioteCfg)); + nrfx_gpiote_out_task_enable(pin); + nrf_ppi_channel_endpoint_setup(ppiBacklightOff, + reinterpret_cast<uint32_t>(&RTC->EVENTS_COMPARE[0]), + nrfx_gpiote_out_task_addr_get(pin)); + nrf_ppi_channel_endpoint_setup(ppiBacklightOn, + reinterpret_cast<uint32_t>(&RTC->EVENTS_COMPARE[1]), + nrfx_gpiote_out_task_addr_get(pin)); + nrf_ppi_fork_endpoint_setup(ppiBacklightOn, reinterpret_cast<uint32_t>(&RTC->TASKS_CLEAR)); + nrf_ppi_channel_enable(ppiBacklightOff); + nrf_ppi_channel_enable(ppiBacklightOn); + } else { + // If the pin used for PWM isn't changing, we only need to set the pin state to the initial value (low) + RTC->TASKS_STOP = 1; + nrf_delay_us(rtcStopTime); + // Due to errata 20,179 and the intricacies of RTC timing, keep it simple: override the pin state + nrfx_gpiote_out_task_force(pin, false); + } + // CC0 switches the backlight off (pin transitions from low to high) + RTC->CC[0] = rawBrightness; + RTC->TASKS_CLEAR = 1; + RTC->TASKS_START = 1; + lastPin = pin; + } + switch (pin) { + case PinMap::LcdBacklightHigh: + nrf_gpio_pin_clear(PinMap::LcdBacklightLow); + nrf_gpio_pin_clear(PinMap::LcdBacklightMedium); + break; + case PinMap::LcdBacklightMedium: + nrf_gpio_pin_clear(PinMap::LcdBacklightLow); + nrf_gpio_pin_set(PinMap::LcdBacklightHigh); + break; + case PinMap::LcdBacklightLow: + nrf_gpio_pin_set(PinMap::LcdBacklightMedium); + nrf_gpio_pin_set(PinMap::LcdBacklightHigh); + } +} + void BrightnessController::Set(BrightnessController::Levels level) { this->level = level; switch (level) { default: case Levels::High: - nrf_gpio_pin_clear(PinMap::LcdBacklightLow); - nrf_gpio_pin_clear(PinMap::LcdBacklightMedium); - nrf_gpio_pin_clear(PinMap::LcdBacklightHigh); + ApplyBrightness(3 * timerPeriod); break; case Levels::Medium: - nrf_gpio_pin_clear(PinMap::LcdBacklightLow); - nrf_gpio_pin_clear(PinMap::LcdBacklightMedium); - nrf_gpio_pin_set(PinMap::LcdBacklightHigh); + ApplyBrightness(2 * timerPeriod); break; case Levels::Low: - nrf_gpio_pin_clear(PinMap::LcdBacklightLow); - nrf_gpio_pin_set(PinMap::LcdBacklightMedium); - nrf_gpio_pin_set(PinMap::LcdBacklightHigh); + ApplyBrightness(timerPeriod); + break; + case Levels::AlwaysOn: + ApplyBrightness(timerPeriod / 10); break; case Levels::Off: - nrf_gpio_pin_set(PinMap::LcdBacklightLow); - nrf_gpio_pin_set(PinMap::LcdBacklightMedium); - nrf_gpio_pin_set(PinMap::LcdBacklightHigh); + ApplyBrightness(0); break; } } diff --git a/src/components/brightness/BrightnessController.h b/src/components/brightness/BrightnessController.h index 7f86759a67802b3526e63e59e650bcc644401345..650749a83cdf330b5292b4d2a8126959807a1d55 100644 --- a/src/components/brightness/BrightnessController.h +++ b/src/components/brightness/BrightnessController.h @@ -2,11 +2,14 @@ #pragma once #include <cstdint> +#include "nrf_ppi.h" +#include "nrfx_gpiote.h" + namespace Pinetime { namespace Controllers { class BrightnessController { public: - enum class Levels { Off, Low, Medium, High }; + enum class Levels { Off, AlwaysOn, Low, Medium, High }; void Init(); void Set(Levels level); @@ -20,6 +23,25 @@ const char* ToString(); private: Levels level = Levels::High; + static constexpr uint8_t UNSET = UINT8_MAX; + uint8_t lastPin = UNSET; + // Maximum time (μs) it takes for the RTC to fully stop + static constexpr uint8_t rtcStopTime = 46; + // Frequency of timer used for PWM (Hz) + static constexpr uint16_t timerFrequency = 32768; + // Backlight PWM frequency (Hz) + static constexpr uint16_t pwmFreq = 1000; + // Wraparound point in timer ticks + // Defines the number of brightness levels between each pin + static constexpr uint16_t timerPeriod = timerFrequency / pwmFreq; + // Warning: nimble reserves some PPIs + // https://github.com/InfiniTimeOrg/InfiniTime/blob/034d83fe6baf1ab3875a34f8cee387e24410a824/src/libs/mynewt-nimble/nimble/drivers/nrf52/src/ble_phy.c#L53 + // SpiMaster uses PPI 0 for an erratum workaround + // Channel 1, 2 should be free to use + static constexpr nrf_ppi_channel_t ppiBacklightOn = NRF_PPI_CHANNEL1; + static constexpr nrf_ppi_channel_t ppiBacklightOff = NRF_PPI_CHANNEL2; + + void ApplyBrightness(uint16_t val); }; } } diff --git a/src/displayapp/DisplayApp.cpp b/src/displayapp/DisplayApp.cpp index c7fb62abc582f79b42f8a6f860b6d8316b0328e1..5e68ef23bb4d5ec21c2b84ca59006c33a0a29507 100644 --- a/src/displayapp/DisplayApp.cpp +++ b/src/displayapp/DisplayApp.cpp @@ -242,11 +242,17 @@ case Messages::RestoreBrightness: RestoreBrightness(); break; case Messages::GoToSleep: - while (brightnessController.Level() != Controllers::BrightnessController::Levels::Off) { + while (brightnessController.Level() != Controllers::BrightnessController::Levels::Low) { brightnessController.Lower(); vTaskDelay(100); } - lcd.Sleep(); + // Don't actually turn off the display for AlwaysOn mode + if (settingsController.GetAlwaysOnDisplay()) { + brightnessController.Set(Controllers::BrightnessController::Levels::AlwaysOn); + } else { + brightnessController.Set(Controllers::BrightnessController::Levels::Off); + lcd.Sleep(); + } PushMessageToSystemTask(Pinetime::System::Messages::OnDisplayTaskSleeping); state = States::Idle; break; diff --git a/src/systemtask/SystemTask.cpp b/src/systemtask/SystemTask.cpp index fb7493aaf5b4b932f26d030394ebb102384d8f6c..0dea5f9813f42a7c96c873efb0d3efe49f2c029e 100644 --- a/src/systemtask/SystemTask.cpp +++ b/src/systemtask/SystemTask.cpp @@ -102,7 +102,9 @@ watchdog.Setup(7, Drivers::Watchdog::SleepBehaviour::Run, Drivers::Watchdog::HaltBehaviour::Pause); watchdog.Start(); NRF_LOG_INFO("Last reset reason : %s", Pinetime::Drivers::ResetReasonToString(watchdog.GetResetReason())); - APP_GPIOTE_INIT(2); + if (!nrfx_gpiote_is_init()) { + nrfx_gpiote_init(); + } spi.Init(); spiNorFlash.Init();