aod: switch to 8 colors when always on

src/displayapp/DisplayApp.cpp

@@ -249,6 +249,7 @@ void DisplayApp::Refresh() {
         // Don't actually turn off the display for AlwaysOn mode
         if (settingsController.GetAlwaysOnDisplay()) {
           brightnessController.Set(Controllers::BrightnessController::Levels::AlwaysOn);
+          lcd.LowPowerOn();
         } else {
           brightnessController.Set(Controllers::BrightnessController::Levels::Off);
           lcd.Sleep();
@@ -257,7 +258,11 @@ void DisplayApp::Refresh() {
         state = States::Idle;
         break;
       case Messages::GoToRunning:
-        lcd.Wakeup();
+        if (settingsController.GetAlwaysOnDisplay()) {
+          lcd.LowPowerOff();
+        } else {
+          lcd.Wakeup();
+        }
         lv_disp_trig_activity(nullptr);
         ApplyBrightness();
         state = States::Running;

src/drivers/St7789.cpp

@@ -127,6 +127,14 @@ void St7789::NormalModeOn() {
   WriteCommand(static_cast<uint8_t>(Commands::NormalModeOn));
 }
 
+void St7789::IdleModeOn() {
+  WriteCommand(static_cast<uint8_t>(Commands::IdleModeOn));
+}
+
+void St7789::IdleModeOff() {
+  WriteCommand(static_cast<uint8_t>(Commands::IdleModeOff));
+}
+
 void St7789::DisplayOn() {
   WriteCommand(static_cast<uint8_t>(Commands::DisplayOn));
 }
@@ -198,6 +206,16 @@ void St7789::HardwareReset() {
   vTaskDelay(pdMS_TO_TICKS(125));
 }
 
+void St7789::LowPowerOn() {
+  IdleModeOn();
+  NRF_LOG_INFO("[LCD] Low power mode");
+}
+
+void St7789::LowPowerOff() {
+  IdleModeOff();
+  NRF_LOG_INFO("[LCD] Normal power mode");
+}
+
 void St7789::Sleep() {
   SleepIn();
   nrf_gpio_cfg_default(pinDataCommand);

src/drivers/St7789.h

@@ -24,6 +24,8 @@ namespace Pinetime {
 
       void DrawBuffer(uint16_t x, uint16_t y, uint16_t width, uint16_t height, const uint8_t* data, size_t size);
 
+      void LowPowerOn();
+      void LowPowerOff();
       void Sleep();
       void Wakeup();
 
@@ -45,6 +47,8 @@ namespace Pinetime {
       void DisplayInversionOn();
       void NormalModeOn();
       void WriteToRam(const uint8_t* data, size_t size);
+      void IdleModeOn();
+      void IdleModeOff();
       void DisplayOn();
       void DisplayOff();
 
@@ -68,6 +72,8 @@ namespace Pinetime {
         MemoryDataAccessControl = 0x36,
         VerticalScrollDefinition = 0x33,
         VerticalScrollStartAddress = 0x37,
+        IdleModeOff = 0x38,
+        IdleModeOn = 0x39,
         PixelFormat = 0x3a,
         VdvSet = 0xc4,
       };