From 08768559d05d1a36dc915a0269d78e97528b2383 Mon Sep 17 00:00:00 2001
From: Ethan Zonca <e@ethanzonca.com>
Date: Mon, 25 Jan 2016 14:12:13 -0500
Subject: [PATCH] Added nicer status LED handling: LED blinks for every tx/rx
 and guarantees at least as much off time as on time

---
 Inc/led.h  | 10 ++++++++++
 Makefile   |  2 +-
 Src/can.c  |  5 +++--
 Src/led.c  | 35 +++++++++++++++++++++++++++++++++++
 Src/main.c | 31 ++++++++++++++++++++++---------
 5 files changed, 71 insertions(+), 12 deletions(-)
 create mode 100644 Inc/led.h
 create mode 100644 Src/led.c

diff --git a/Inc/led.h b/Inc/led.h
new file mode 100644
index 0000000..38d0e0a
--- /dev/null
+++ b/Inc/led.h
@@ -0,0 +1,10 @@
+#ifndef _LED_H
+#define _LED_H
+
+
+#define LED_DURATION 50
+
+void led_on(void);
+void led_process(void);
+
+#endif
diff --git a/Makefile b/Makefile
index c47bc2e..3e766b0 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,7 @@
 BUILD_NUMBER ?= 0
 
 # SOURCES: list of sources in the user application
-SOURCES = main.c usbd_conf.c usbd_cdc_if.c usb_device.c usbd_desc.c stm32f0xx_hal_msp.c stm32f0xx_it.c system_stm32f0xx.c can.c slcan.c
+SOURCES = main.c usbd_conf.c usbd_cdc_if.c usb_device.c usbd_desc.c stm32f0xx_hal_msp.c stm32f0xx_it.c system_stm32f0xx.c can.c slcan.c led.c
 
 # TARGET: name of the user application
 TARGET = CANtact-b$(BUILD_NUMBER)
diff --git a/Src/can.c b/Src/can.c
index 1ba3636..04825bf 100644
--- a/Src/can.c
+++ b/Src/can.c
@@ -1,5 +1,6 @@
 #include "stm32f0xx_hal.h"
 #include "can.h"
+#include "led.h"
 
 CAN_HandleTypeDef hcan;
 CAN_FilterConfTypeDef filter;
@@ -113,7 +114,7 @@ uint32_t can_tx(CanTxMsgTypeDef *tx_msg, uint32_t timeout) {
     hcan.pTxMsg = tx_msg;
     status = HAL_CAN_Transmit(&hcan, timeout);
 
-    HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_1);
+	led_on();
     return status;
 }
 
@@ -124,7 +125,7 @@ uint32_t can_rx(CanRxMsgTypeDef *rx_msg, uint32_t timeout) {
 
     status = HAL_CAN_Receive(&hcan, CAN_FIFO0, timeout);
 
-    HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_1);
+	led_on();
     return status;
 }
 
diff --git a/Src/led.c b/Src/led.c
new file mode 100644
index 0000000..762539f
--- /dev/null
+++ b/Src/led.c
@@ -0,0 +1,35 @@
+//
+// LED: Handles blinking of status light
+//
+
+#include "stm32f0xx_hal.h"
+#include "led.h"
+
+static uint32_t led_laston = 0;
+static uint32_t led_lastoff = 0;
+
+// Attempt to turn on status LED
+void led_on(void)
+{
+	// Make sure the LED has been off for at least LED_DURATION before turning on again
+	// This prevents a solid status LED on a busy canbus
+	if(led_laston == 0 && HAL_GetTick() - led_lastoff > LED_DURATION)
+	{
+		HAL_GPIO_WritePin(GPIOB, GPIO_PIN_1, 1);
+		led_laston = HAL_GetTick();
+	}
+}
+
+
+// Process time-based LED events
+void led_process(void)
+{
+	// If LED has been on for long enough, turn it off
+	if(led_laston > 0 && HAL_GetTick() - led_laston > LED_DURATION)
+	{
+		HAL_GPIO_WritePin(GPIOB, GPIO_PIN_1, 0);
+		led_laston = 0;
+		led_lastoff = HAL_GetTick();
+	}
+}
+
diff --git a/Src/main.c b/Src/main.c
index adb3e43..55d1248 100644
--- a/Src/main.c
+++ b/Src/main.c
@@ -40,9 +40,10 @@
 #include "usbd_cdc_if.h"
 #include "can.h"
 #include "slcan.h"
+#include "led.h"
 
-//#define INTERNAL_OSCILLATOR
-#define EXTERNAL_OSCILLATOR
+#define INTERNAL_OSCILLATOR
+//#define EXTERNAL_OSCILLATOR
 
 /* USER CODE END Includes */
 
@@ -65,6 +66,7 @@ static void led_init(void);
 
 /* USER CODE END 0 */
 
+
 volatile int i=0;
 int main(void)
 {
@@ -98,7 +100,11 @@ int main(void)
     // blink red LED for test
     uint32_t count;
     HAL_GPIO_WritePin(GPIOB, GPIO_PIN_1, GPIO_PIN_SET);
-    for (count=0; count < 200000; count++) { __asm("nop");}
+	HAL_Delay(100);
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_1, GPIO_PIN_RESET);
+	HAL_Delay(100);
+    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_1, GPIO_PIN_SET);
+	HAL_Delay(100);
     HAL_GPIO_WritePin(GPIOB, GPIO_PIN_1, GPIO_PIN_RESET);
 
     // loop forever
@@ -106,13 +112,16 @@ int main(void)
     uint32_t status;
     uint8_t msg_buf[SLCAN_MTU];
 
+
     for (;;) {
-	while (!is_can_msg_pending());
-	status = can_rx(&rx_msg, 3);
-	if (status == HAL_OK) {
-	    status = slcan_parse_frame(&msg_buf, &rx_msg);
-	    CDC_Transmit_FS(msg_buf, status);
-	}
+		while (!is_can_msg_pending())
+			led_process();
+		status = can_rx(&rx_msg, 3);
+		if (status == HAL_OK) {
+			status = slcan_parse_frame(&msg_buf, &rx_msg);
+			CDC_Transmit_FS(msg_buf, status);
+		}
+		led_process();
     }
 
     /* USER CODE END 3 */
@@ -177,6 +186,10 @@ void SystemClock_Config(void)
     HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit);
     __SYSCFG_CLK_ENABLE();
 
+	HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
+	HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);
+    HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
+
 }
 
 /** Configure pins as