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aod: PPI/RTC-based backlight brightness

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This commit is contained in:
mark9064 2024-01-22 23:37:52 +00:00 committed by JF
parent 20ac7e8df3
commit 3dca742b65
4 changed files with 146 additions and 16 deletions
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124
src/components/brightness/BrightnessController.cpp
View File

@ -2,38 +2,138 @@
#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;
}
}

24
src/components/brightness/BrightnessController.h
View File

@ -2,11 +2,14 @@
#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 @@ namespace Pinetime {
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);
};
}
}

8
src/displayapp/DisplayApp.cpp
View File

@ -242,11 +242,17 @@ void DisplayApp::Refresh() {
RestoreBrightness();
break;
case Messages::GoToSleep:
while (brightnessController.Level() != Controllers::BrightnessController::Levels::Off) {
while (brightnessController.Level() != Controllers::BrightnessController::Levels::Low) {
brightnessController.Lower();
vTaskDelay(100);
}
// 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;

4
src/systemtask/SystemTask.cpp
View File

@ -102,7 +102,9 @@ void SystemTask::Work() {
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();