Use longer period for PXX2 modules triggered by heartbeat signal and reset timer early

This allows to cope for the different frame rates used by ACCESS and ACCST modes. See opentx/opentx#8601 for details.

radio/src/pulses/pxx.h

@@ -30,7 +30,7 @@
 #define PXX2_LOWSPEED_BAUDRATE             230400
 #define PXX2_HIGHSPEED_BAUDRATE            450000
 #define PXX2_NO_HEARTBEAT_PERIOD           4000/*us*/
-#define PXX2_MAX_HEARTBEAT_PERIOD          (7000 + 1000)/*us 7ms frame rate + 1ms heartbeat backup*/
+#define PXX2_MAX_HEARTBEAT_PERIOD          (9000 + 1000)/*us longest period (isrm/accst) + 1ms heartbeat backup*/
 #define PXX2_TOOLS_PERIOD                  1000/*us*/
 #define PXX2_FRAME_MAXLENGTH               64
 

radio/src/targets/common/arm/stm32/heartbeat_driver.cpp

@@ -79,6 +79,7 @@ void check_intmodule_heartbeat()
 #endif
     EXTI_ClearITPendingBit(INTMODULE_HEARTBEAT_EXTI_LINE);
 
+    mixerSchedulerResetTimer();
     mixerSchedulerISRTrigger();
   }
 }