[bl] add Leonardo-like led pulse

Author: facchinm

bootloaders/zero/board_driver_led.h

@@ -38,4 +38,6 @@ inline void LEDTX_on(void) { PORT->Group[BOARD_LEDTX_PORT].OUTCLR.reg = (1<<BOAR
 inline void LEDTX_off(void) { PORT->Group[BOARD_LEDTX_PORT].OUTSET.reg = (1<<BOARD_LEDTX_PIN); }
 inline void LEDTX_toggle(void) { PORT->Group[BOARD_LEDTX_PORT].OUTTGL.reg = (1<<BOARD_LEDTX_PIN); }
 
+inline void LED_configure(uint32_t sampleRate) { SysTick_Config(sampleRate); }
+
 #endif // _BOARD_DRIVER_LED_

bootloaders/zero/board_startup.c

@@ -18,6 +18,7 @@
 */
 
 #include <sam.h>
+#include "board_driver_led.h"
 
 struct ConstVectors
 {
@@ -140,8 +141,25 @@ void PendSV_Handler(void)
   while (1);
 }
 
+volatile uint8_t keepValue = 0;
+volatile uint8_t targetValue = 20;
+volatile int8_t direction = 1;
+
 void SysTick_Handler(void)
 {
-  __BKPT(1);
-  while (1);
-}
+  if (keepValue == 0) {
+    targetValue += direction;
+    LED_toggle();
+  }
+  keepValue ++;
+
+  if (targetValue > 240 || targetValue < 10) {
+    direction = -direction;
+    targetValue += direction;
+  }
+
+  if (keepValue == targetValue) {
+    LED_toggle();
+  }
+  //TC5->COUNT16.INTFLAG.bit.MC0 = 1;     // Clear interrupt
+}

bootloaders/zero/main.c

@@ -181,7 +181,7 @@ int main(void)
 
   /* Initialize LEDs */
   LED_init();
-  LED_on();
+  LED_configure(1000);
   LEDRX_init();
   LEDRX_off();
   LEDTX_init();