1 files changed, 47 insertions(+), 6 deletions(-)

M arm03/src/main.c

@@ 1,8 1,10 @@
+#include "stm32f401xe.h"
+#include "timer.h"
 #include <stdint.h>
+#include <stdbool.h>
 #include <stm32f4xx.h>
 #include "exti.h"
 #include "pin.h"
-#include "timer.h"
 #include "registers.h"
 #include "display.h"
 #include "delay.h"


@@ 75,6 77,8 @@ exti_t startstop_exti;
 pin_t startstop_button;
 pin_t null_button;
 
+bool counting;
+
 void null_timer(void);
 void toggle_timer(void);
 


@@ 132,9 136,27 @@ void main()
   }
 
   timer_init(&stopwatch_timer, TIM2, 2);
+  timer_set_counter(&stopwatch_timer, 0);
   timer_configure(&stopwatch_timer, 0, 60000, 0);
   timer_set_refresh(&stopwatch_timer, 10000*4);
 
+  {
+    pin_t pin_capture;
+    pin_init(&pin_capture, GPIOA, 1);
+    pin_into_alternate(&pin_capture, 1);
+
+    reg_write_bits(&stopwatch_timer.periph->CCMR1,
+    //             TI2 on CCR1              no prescaler - capture every event  sampling freq = fdts / 32, N = 8
+    //                                                                          fdts = 24 MHz, fsample = 750kHz
+                  (2 << TIM_CCMR1_CC1S_Pos) | (0 << TIM_CCMR1_IC1PSC_Pos) | (0xF << TIM_CCMR1_IC1F_Pos),
+                  TIM_CCMR1_CC1S | TIM_CCMR1_IC1PSC | TIM_CCMR1_IC1F);
+    reg_write_bits(
+        &stopwatch_timer.periph->CCER,
+        //   enable CC1                                 rising edge captures
+        (1 << TIM_CCER_CC1E_Pos) | (0 << TIM_CCER_CC1NP_Pos) | (1 << TIM_CCER_CC1P_Pos),
+        TIM_CCER_CC1E | TIM_CCER_CC1P | TIM_CCER_CC1NP);
+  }
+
   timer_init(&startstop_debounce_timer, TIM4, 4);
   timer_configure(&startstop_debounce_timer, 0, 60000, 1);
   timer_set_refresh(&startstop_debounce_timer, 10);


@@ 148,15 170,37 @@ void main()
 
   __enable_irq();
 
+  bool captured = false;
+  uint32_t capture = 0;
+
   // Application
   while (1) {
     uint32_t count = 0;
     if (!pin_read(&null_button)) {
       null_timer();
+      captured = false;
     } else {
       count = timer_count(&stopwatch_timer) >> 2;
     }
 
+    if (stopwatch_timer.periph->SR & TIM_SR_CC1IF) {
+      reg_clear_bits(&stopwatch_timer.periph->SR, TIM_SR_CC1IF);
+
+      capture = stopwatch_timer.periph->CCR1 >> 2;
+      captured = true;
+    } else if (!counting) {
+      captured = false;
+    }
+
+    if (captured && counting) {
+      // prevent capture wrapping
+      if (count < capture) {
+        count += 10000;
+      }
+
+      count -= capture;
+    }
+
     display_enable_digit(&display, 0,
                          (count % display.max_value) >= 1000);
     display_convert_number(&display, count);


@@ 172,8 216,10 @@ void null_timer(void) {
 void toggle_timer(void) {
   if (timer_is_enabled(&stopwatch_timer)) {
     timer_disable(&stopwatch_timer);
+    counting = false;
   } else {
     timer_enable(&stopwatch_timer);
+    counting = true;
   }
 }
 


@@ 183,11 229,6 @@ void EXTI0_handler(void) {
   timer_enable(&startstop_debounce_timer);
 }
 
-void EXTI4_handler(void) {
-  exti_clear_interrupt(&null_button);
-  null_timer();
-}
-
 /* void TIM2_handler(void) { */
 /*   // The stopwatch timer */
 /* } */