From a07e287865ddfa16a997ed000508cdc64cf72c38 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Sun, 3 Apr 2016 21:29:04 +0200
Subject: [PATCH] use internal RTC with our tick speed

---
 main.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/main.c b/main.c
index 24b8165..e101458 100644
--- a/main.c
+++ b/main.c
@@ -39,6 +39,7 @@
 #include <libopencm3/stm32/exti.h> // external interrupt utilities
 #include <libopencm3/stm32/timer.h> // timer utilities
 #include <libopencm3/stm32/adc.h> // ADC utilities
+#include <libopencm3/stm32/rtc.h> // real time clock utilities
 
 /* own libraries */
 #include "global.h" // board definitions
@@ -368,6 +369,11 @@ int main(void)
 	nvic_enable_irq(BUTTON_IRQ); // enable interrupt
 #endif
 
+	// setup RTC
+	rtc_auto_awake(RCC_LSE, 32768/TICKS_PER_SECOND-1); // ensure RTC is on, uses the 32.678 kHz LSE, and the prescale is set to our tick speed, else update backup registers accordingly
+	rtc_interrupt_enable(RTC_SEC); // enable RTC interrupt on "seconds"
+	nvic_enable_irq(NVIC_RTC_IRQ); // allow the RTC to interrupt
+
 	// generate gamma correction table (with fixed gamma value)
 	for (uint16_t i=0; i<LENGTH(gamma_correction_lut); i++) {
 		gamma_correction_lut[i] = powf((float)i / (float)LENGTH(gamma_correction_lut), 2.2)*LENGTH(gamma_correction_lut);
@@ -465,19 +471,18 @@ int main(void)
 			time_flag = false; // reset flag
 			action = true; // action has been performed
 			if ((current_time%ticks_second)==0) { // one second passed
-				//printf("%02lu:%02lu:%02lu\n", current_time/ticks_hour, (current_time%ticks_hour)/ticks_minute, (current_time%ticks_minute)/ticks_second); // display time
+				led_toggle(); // LED activity to show we are not stuck
 			}
 			if ((current_time%ticks_minute)==0) { // one minute passed
-				//current_time = rtc_time[2]*ticks_hour+rtc_time[1]*ticks_minute+rtc_time[0]*ticks_second; // sync current time
 				printf("it is now %02lu:%02lu:%02lu\n", current_time/ticks_hour, (current_time%ticks_hour)/ticks_minute, (current_time%ticks_minute)/ticks_second); // display time
 			}
 			if ((current_time%ticks_hour)==0) { // one hours passed
 				clock_hours(); // show hour markers
 			}
+			if ((current_time%ticks_midday*2)==0) { // one day passed
+				current_time = 0; // reset time counter
+            }
 			clock_set_time(current_time); // set time
-			if ((current_time%ticks_second)==0) { // on second passed
-				//printf("%02lu:%02lu:%02lu\n", current_time/ticks_hour, (current_time%ticks_hour)/ticks_minute, (current_time%ticks_minute)/ticks_second); // display time
-			}
 		}
 		if (action) { // go to sleep if nothing had to be done, else recheck for activity
 			action = false;
@@ -496,3 +501,10 @@ void BUTTON_ISR(void)
 	button_flag = true; // perform button action
 }
 #endif
+
+void rtc_isr(void)
+{
+	rtc_clear_flag(RTC_SEC); // clear flag
+	current_time++; // increment time
+	time_flag = true; // notify to show new time
+}