Add power-down mode for LED driver

build-number.txt

@@ -1 +1 @@
-375
+389

src/led.c

@@ -3,6 +3,7 @@
 
 LED_Colour_t LED_PixelData[LED_COUNT] = {{0}};
 volatile bool LED_FrameFlag = false;
+volatile bool LED_SuspendFlag = false;
 
 #define LED_ODR_MASK            ((1 << PIN_LED_R_0) | (1 << PIN_LED_G_0) \
                                 | (1 << PIN_LED_B_0) | (1 << PIN_LED_R_1) \
@@ -215,6 +216,7 @@ void LED_Init(void)
     RCC->APB1ENR |= RCC_APB1ENR_TIM3EN;
 
     // Fill both DMA buffers
+    LED_QueuePageFlip = false;
     LED_Commit();
     LED_PageFlip();
     LED_Commit();
@@ -244,6 +246,39 @@ void LED_Init(void)
     LED_StartBCM(0);
 }
 
+void LED_Suspend(void)
+{
+    LED_SuspendFlag = true;
+    while(LED_SuspendFlag);
+
+    // Disable timer and DMA channels
+    TIM3->CR1 = 0x0000;
+    TIM3->DIER = 0x0000;
+    TIM3->CNT = 0;
+    DMA1->IFCR = DMA_IFCR_CTCIF3;
+    DMA1_Channel3->CCR = 0x0000;
+    DMA1_Channel4->CCR = 0x0000;
+    NVIC_DisableIRQ(DMA1_Channel2_3_IRQn);
+    NVIC_ClearPendingIRQ(DMA1_Channel2_3_IRQn);
+
+    // Deactivate all rows and columns
+    GPIOA->BSRR = LED_ODR_MASK;
+    GPIOF->BSRR = (1 << PIN_ROW_DATA);
+    for(int i = 0; i < LED_ROWS + 1; i++)
+    {
+        LED_PulseRowClock();
+    }
+
+    // Disable timer and DMA clocks
+    RCC->AHBENR &= ~RCC_AHBENR_DMA1EN;
+    RCC->APB1ENR &= ~RCC_APB1ENR_TIM3EN;
+}
+
+void LED_WakeUp(void)
+{
+    LED_Init();
+}
+
 void DMA1_Channel2_3_IRQHandler(void)
 {
     // Interrupt when all bits have been sent
@@ -268,6 +303,12 @@ void DMA1_Channel2_3_IRQHandler(void)
         LED_PulseRowClock();
     }
 
+    if(LED_SuspendFlag)
+    {
+        LED_SuspendFlag = false;
+        return;
+    }
+
     // Start sending bits out again. The row offset caused by the shift
     // register "lagging" one clock cycle behind because RCK and SCK are
     // connected to the same signal doesn't matter here: we're not paying much

src/led.h

@@ -27,6 +27,12 @@ extern volatile bool LED_FrameFlag;
 void LED_InitShiftRegister(void);
 void LED_Init(void);
 
+// Enter power-saving mode (LEDs off)
+void LED_Suspend(void);
+
+// Leave power-saving mode
+void LED_WakeUp(void);
+
 // Display LED_PixelData, starting with the next frame
 void LED_Commit(void);
 

src/main.c

@@ -5,6 +5,8 @@ int main(void)
     LED_InitShiftRegister();
     LightSensor_Init();
 
+    bool powered_down = false;
+
     // Delay a bit to make programming easier
     for(unsigned int i = 0; i < 1000; i++)
     {
@@ -18,6 +20,17 @@ int main(void)
         __WFI();
         LightSensor_Poll();
         Animation_Poll();
+
+        if(LightSensor_RelativeBrightness == 0 && !powered_down)
+        {
+            LED_Suspend();
+            powered_down = true;
+        }
+        if(powered_down && LightSensor_RelativeBrightness > 0)
+        {
+            LED_WakeUp();
+            powered_down = false;
+        }
     }
 
     return 0;

src/main.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <string.h>
+#include <stdbool.h>
 
 #include "stm32f030x6.h"
 #include "buildid.h"