drv/stk.c

@@ -17,6 +17,7 @@
 
 static volatile struct STK* regs = (struct STK*)STK_BASE_ADDRESS;
 
+
 //--local variables-------------------------------------------------------------
 
 static StkCallback callback;
@@ -80,5 +81,7 @@ uint32_t stk_read(void)
 
 void hdr_sys_tick(void)
 {
+	//clearing the pending bit in SCB_ICSR isn't needed, though I don't know why
 	callback();
 }
+

drv/stk.h

@@ -20,10 +20,34 @@ typedef void (*StkCallback)(void);
 
 //--functions-------------------------------------------------------------------
 
+/**
+ * Configures the system timer to run at the specified period in µs and call the
+ * given callback when said period is reached. Due to the limited configuration
+ * options, 1.8s is the maximum period when running in speed preset (see rcc
+ * module). The maximum period can be substantially increased by reducing the
+ * core clock
+ */
 uint32_t stk_configure(uint32_t period_us, StkCallback cb);
+
+/**
+ * Resets the system timer configuration, restoring the default configuration
+ * and stopping it
+ */
 void stk_reset(void);
+
+/**
+ * Starts the system timer. The timer will run until stopped
+ */
 void stk_start(void);
+
+/**
+ * Stops the system timer
+ */
 void stk_stop(void);
+
+/**
+ * Read the current value of the timer's counter
+ */
 uint32_t stk_read(void);