Add a commented interrupt latency measurement example

examples/c/interrupt_latency.c

@@ -0,0 +1,42 @@
+#include <stdint.h>
+
+// The size of these variables should match the size of the timer value.
+uint32_t min_latency = UINT32_MAX;
+uint32_t max_latency = 0;
+// Note that the type of total_latency is larger than min/max latency.
+// This is because total_latency is an accumulator and may overflow.
+uint64_t total_latency = 0;
+
+/// Later in your program you can calculate average latency using total_latency / count.
+uint32_t count = 0;
+
+__attribute__((weak)) inline uint32_t readTimer()
+{
+	// Override this function to read from the target timer peripheral.
+	// Our advice is to read the raw timer value in as few steps as possible,
+	// skipping any conversion steps. This will give you the most accurate look
+	// at interrupt latency. The application code (or a spreadsheet) can handle
+	// the conversion from count to time for you.
+	return 0;
+}
+
+// Call this function from the timer interrupt handler
+void latency(void)
+{
+	uint32_t time = readTimer();
+
+	if(time < min_latency)
+	{
+		min_latency = time;
+	}
+
+	if(time > max_latency)
+	{
+		max_latency = time;
+	}
+
+	total_latency += time;
+	count++;
+}
+
+

examples/c/meson.build

@@ -1,5 +1,9 @@
 # C examples Meson Build File
 
+static_library('interrupt_latency',
+	'interrupt_latency.c'
+)
+
 executable('circular_buffer',
 	[
 		'circular_buffer_test.c',