STM32H745 EXTI and SYSCFG_EXTICRx relation

[Matt__]

Hello, 

   I am trying to better understand the relation of how the SYSCFG_EXTICRx and the EXTI_RTSR1 registers correspond. In the manual as I understand, the SYSCFG_EXTICRx registers are used to setup a pin on the EXTI line for interrupt use by setting your desired port config. Looking in the manual at the EXTI_RTSR1 register, I believe the 0-15 bits are used for the corresponding lines that the SYSCFG_EXTICRx register sets. However, there is bits 16-21 which if anyone knows what or how they are used? 

   Any clarification would be appreciated. I am just trying to clarify my understanding is correct and what these other bits are referring to. 

Thanks

[SofLit · Accepted solution]

Hello,

The EXI lines are not only used for pins but also to be triggered by internal signals:

See "Event input type" in table 152. If it's configurable, there is a corresponding bit in EXTI_RTSRx registers.

See table RM0399/ Table 152

Hope it does answer your question.