From 21067f5f4c7cf8ed5874f8d662abb22b2ca9e230 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Tue, 11 Oct 2022 19:06:28 +0200
Subject: [PATCH] main: control RGB LED using PWM

---
 main.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 48 insertions(+), 2 deletions(-)

diff --git a/main.c b/main.c
index 5a90b4a..4a9287d 100644
--- a/main.c
+++ b/main.c
@@ -87,6 +87,27 @@ void puth(uint8_t h)
 	putn(h & 0x0f);
 }
 
+// set duty cycle of red LED
+void led_red(uint16_t bightness)
+{
+	TIM2->CCR2H.reg = (bightness >> 8); // set duty cycle
+	TIM2->CCR2L.reg = (bightness >> 0); // set duty cycle
+}
+
+// set duty cycle of green LED
+void led_green(uint16_t bightness)
+{
+	TIM2->CCR3H.reg = (bightness >> 8); // set duty cycle
+	TIM2->CCR3L.reg = (bightness >> 0); // set duty cycle
+}
+
+// set duty cycle of blue LED
+void led_blue(uint16_t bightness)
+{
+	TIM2->CCR1H.reg = (bightness >> 8); // set duty cycle
+	TIM2->CCR1L.reg = (bightness >> 0); // set duty cycle
+}
+
 void main(void)
 {
 	sim(); // disable interrupts (while we reconfigure them)
@@ -127,7 +148,8 @@ void main(void)
 	IRM_ON_PORT->CR1.reg |= IRM_ON_PIN; // use as push-pull
 	IRM_ON_PORT->DDR.reg |= IRM_ON_PIN; // switch pin to output
 
-	// configure RGB LED
+
+/* use PWM instead of GPIO for controlling RGB LED
 	LED_RED_PORT->ODR.reg &= ~LED_RED_PIN; // switch LED off
 	LED_RED_PORT->CR1.reg |= LED_RED_PIN; // use as push-pull
 	LED_RED_PORT->DDR.reg |= LED_RED_PIN; // use pin to output
@@ -137,6 +159,26 @@ void main(void)
 	LED_BLUE_PORT->ODR.reg &= ~LED_BLUE_PIN; // switch LED off
 	LED_BLUE_PORT->CR1.reg |= LED_BLUE_PIN; // use as push-pull
 	LED_BLUE_PORT->DDR.reg |= LED_BLUE_PIN; // use pin to output
+*/
+
+	// configure timer 2 for PWM-controlling RGB LED
+	TIM2->PSCR.fields.PSC = 0; // set prescaler to to 244 Hz, 16E6/(2**0)/65536 = 244 Hz
+	TIM2->ARRH.reg = 0xff; // set period to max for most precisions
+	TIM2->ARRL.reg = 0xff; // set period to max for most precisions
+	TIM2->CCMR1.output_fields.OC1M = 6; // set PWM1 mode
+	TIM2->CCMR1.output_fields.CC1S = 0; // use channel as output
+	TIM2->CCER1.fields.CC1E = 1; // enable channel output
+	led_blue(0); // switch off blue LED
+	TIM2->CCMR2.output_fields.OC2M = 6; // set PWM1 mode
+	TIM2->CCMR2.output_fields.CC2S = 0; // use channel as output
+	TIM2->CCER1.fields.CC2E = 1; // enable channel output
+	led_red(0); // switch off red LED
+	TIM2->CCMR3.output_fields.OC3M = 6; // set PWM1 mode
+	TIM2->CCMR3.output_fields.CC3S = 0; // use channel as output
+	TIM2->CCER2.fields.CC3E = 1; // enable channel output
+	led_green(0); // switch off green LED
+	TIM2->EGR.fields.UG = 1; // transfer all registers
+	TIM2->CR1.fields.CEN = 1; // enable counter to start PWM
 
 /*
 	// configure IR LED
@@ -201,7 +243,8 @@ void main(void)
 
 	rim(); // re-enable interrupts
 	bool action = false; // if an action has been performed
-	puts("ready\r\n");
+	led_green(0x0100); // indicate we are ready
+	puts("\r\nready\r\n");
 	while (true) {
 		putc('.');
 		IWDG_KR = IWDG_KR_KEY_REFRESH; // reset watchdog
@@ -214,6 +257,9 @@ void main(void)
 		if (time_count > 488 * 10) {
 			puts("10s\r\n");
 			time_count = 0; // reset counter
+			led_red(0); // ensure LED is off
+			led_green(0); // ensure LED is off
+			led_blue(0); // ensure LED is off
 			halt();
 		}
 		if (action) { // something has been performed, check if other flags have been set meanwhile