Internal Interrupts are used to respond to asynchronous requests from a certain part of the
microcontroller that needs to be serviced. Each peripheral in the TriCore as well as the
Bus Control Unit, the Debug Unit, the Peripheral Control Processor (PCP) and the CPU
itself can generate an Interrupt Request.
So what is an external Interrupt?
An external Interrupt is something alike as the internal Interrupt. The difference is that an
external Interrupt request is caused by an external event. Normally this would be a pulse
on Port0 or Port1, but it can be even a signal from the input buffer of the SSC, indicating
that a service is requested.
The User’s Manual does not explain this aspect in detail so this ApNote will explain the
most common form of an external Interrupt request. This ApNote will show that there is an
easy way to react on a pulse on Port0 or Port1 and to create with this impulse an Interrupt
Service Request. Later in the second part of the document, you can find hints on how to
debounce impulses to enable the use of a simple switch as the input device.
Note: You will find additional information on how to setup the Interrupt System in the
ApNote “First steps through the TriCore Interrupt System” (AP3222xx)1. It would go
beyond the scope of this document to explain this here, but you will find selfexplanatory
examples later on.