docs

firmware/hw_layer/digital_input_hw.cpp

@@ -16,6 +16,8 @@
  * See https://stackoverflow.com/questions/43440599/stm32-multi-channel-input-capture-overcapturing-on-all-channels-interrupts-not
  *    where they seem to be capturing something on multiple channels maybe not PWM mode of ICU is the key difference?
  *
+ * rus084 is reminding that EXTI could be enough for our needs
+ * See joystick.cpp
  *
  * @date Jun 23, 2013
  * @author Andrey Belomutskiy, (c) 2012-2018

firmware/hw_layer/joystick.cpp

@@ -4,6 +4,10 @@
  * See lcd_controller.cpp for more information
  * See void onJoystick(joystick_button_e button)
  *
+ * TODO: separate EXTI layer from joystick logic
+ * TODO: spell out the limitations of EXTI, can we use multiple pins with same index?
+ * See also comments in digital_input_hw.cpp
+ *
  * @date Jan 2, 2015
  * @author Andrey Belomutskiy, (c) 2012-2018
  */