samd: background: Allow monitoring time taken in background task

If you define MONITOR_BACKGROUND_TASK, then a physical output pin
(Metro M4 Express's "SCL" pin by default) will be set HIGH while in
the background task and LOW at other times

1 files changed, 21 insertions, 0 deletions

diff --git a/ports/atmel-samd/background.c b/ports/atmel-samd/background.c
index 3b698768b..ca91a31de 100644
--- a/ports/atmel-samd/background.c
+++ b/ports/atmel-samd/background.c
@@ -45,6 +45,23 @@ bool stack_ok_so_far = true;
 
 static bool running_background_tasks = false;
 
+#ifdef MONITOR_BACKGROUND_TASKS
+// PB03 is physical pin "SCL" on the Metro M4 express
+// so you can't use this code AND an i2c peripheral
+// at the same time unless you change this
+STATIC void start_background_task(void) {
+    REG_PORT_DIRSET1 = (1<<3);
+    REG_PORT_OUTSET1 = (1<<3);
+}
+
+STATIC void finish_background_task(void) {
+    REG_PORT_OUTCLR1 = (1<<3);
+}
+#else
+STATIC void start_background_task(void) {}
+STATIC void finish_background_task(void) {}
+#endif
+
 void background_tasks_reset(void) {
     running_background_tasks = false;
 }
@@ -54,6 +71,9 @@ void run_background_tasks(void) {
     if (running_background_tasks) {
         return;
     }
+
+    start_background_task();
+
     assert_heap_ok();
     running_background_tasks = true;
 
@@ -73,6 +93,7 @@ void run_background_tasks(void) {
     assert_heap_ok();
 
     last_finished_tick = supervisor_ticks_ms64();
+    finish_background_task();
 }
 
 bool background_tasks_ok(void) {