User guide

SmartBook for Renesas R8C/Tiny Microcontrollers

www.MightyMicons.com

initiated. These interrupts also belong to the

hardware group. A few of the controller’s

instructions like Undefined Instruction (UND),

Overflow (INTO), BRK and INT generate non-

maskable interrupts.

For your information, maskable interrupts are the kind

which can be activated or disabled by configuring an

Interrupt enable flag (I flag). Also, the priority levels for

these interrupts can be modified as per the requirement.

Non-maskable interrupts cannot be controlled by initialization.

Under the proper conditions, they are bound to happen for sure.

Each of these interrupts is associated with a four byte long Interrupt Vector.

This vector contains starting address of the service routine meant for that particular

interrupt. The structure of this vector is mentioned below:

These interrupt vectors are arranged in tables. The vectors for most of the non-

maskable interrupts contain fixed and predefined addresses and they are

collectively called as the Fixed Vector Table with the starting address ranging

from 0FFDCH to 0FFFFH. The other table for the interrupt vectors, known as

Relocatable Vector Table meant for the micon peripheral functions and the software

interrupts. The size of this relocatable table is 256 bytes accommodating 64

interrupts with the starting address defined in the INTB register. This vector table

can be created and moved to any memory area as and when it is required by

initializing the INTB register with the table address.

5.2 Software Interrupts:

Software interrupts which are non-maskable kind are activated when certain

instructions are executed.

Each of these interrupts is

associated with a four byte

long Interrupt Vector. This

vector contains starting

address of the service

routine meant for that

particular interrupt.The vectors for most

of the non-maskable interrupts contain

fixed and predefined addresses and

they are collectively called as the

Fixed Vector Table with the

starting address ranging

from 0FFDCH to

0FFFFH.