STM32F411: create timer-stm32.c

Empty, so far.

timer-stm32.c

@@ -0,0 +1,63 @@
+
+/** \file
+  \brief Timer management, ARM specific part.
+
+  To be included from timer.c.
+*/
+
+#if defined TEACUP_C_INCLUDE && defined __ARM_STM32F411__
+
+
+/** Timer initialisation.
+
+  Initialise timer and enable system clock interrupt. Step interrupt is
+  enabled later, when we start using it.
+*/
+void timer_init() {
+}
+
+/** Specify how long until the step timer should fire.
+
+  \param delay Delay for the next step interrupt, in CPU ticks.
+
+  \param check_short Tell whether to check for impossibly short requests. This
+         should be set to 1 for calls from the step interrupt. Short requests
+         then return 1 and do not schedule a timer interrupt. The calling code
+         usually wants to handle this case.
+
+         Calls from elsewhere should set it to 0. In this case a timer
+         interrupt is always scheduled. At the risk that this scheduling
+         doesn't delay the requested time, but up to a full timer counter
+         overflow ( = 65536 / F_CPU = 3 to 4 milliseconds).
+
+  \return A flag whether the requested time was too short to allow scheduling
+          an interrupt. This is meaningful for ACCELERATION_TEMPORAL, where
+          requested delays can be zero or even negative. In this case, the
+          calling code should repeat the stepping code immediately and also
+          assume the timer to not change his idea of when the last step
+          happened.
+
+  Strategy of this timer is to schedule timer interrupts not starting at the
+  time of the call, but starting at the time of the previous timer interrupt
+  fired. This ignores the processing time taken in the step interrupt so far,
+  offering smooth and even step distribution. Flipside of this coin is,
+  schedules issued at an arbitrary time can result in drastically wrong delays.
+  See also discussion of parameter check_short and the return value.
+
+  This enables the step interrupt, but also disables interrupts globally.
+  So, if you use it from inside the step interrupt, make sure to do so
+  as late as possible. If you use it from outside the step interrupt,
+  do a sei() after it to make the interrupt actually fire.
+*/
+uint8_t timer_set(int32_t delay, uint8_t check_short) {
+  return 0;
+}
+
+/** Stop timers.
+
+  This means to be an emergency stop.
+*/
+void timer_stop() {
+}
+
+#endif /* defined TEACUP_C_INCLUDE && defined __ARM_STM32F411__ */

timer.c

@@ -11,6 +11,7 @@
 #define TEACUP_C_INCLUDE
 #include "timer-avr.c"
 #include "timer-lpc.c"
+#include "timer-stm32.c"
 #undef TEACUP_C_INCLUDE
 
 // No common code so far.