Interrupts on STM32 MCUs come in two flavors: internal and external. Both types of interrupts use the same core peripheral in the Cortex-M core: the Nested Vectored Interrupt Controller , or NVIC.

Test equipment receives data over RS485 and loops back the same data to DUT - STM32 over RS485 interface. At DUT - STM32, the received data is compared with the transmitted data. Ethernet Test Task: ...