Renesas R8C/25 Instrukcja Obsługi Pobierz pdf (Strona 7)

Rev. 1.1

R8C25 QuickDesign Guide.doc Page 7 of 10 12/23/2007

8. Interrupts

The R8C has individual interrupts for nearly all peripherals. The interrupts can have

individual priorities and separate vector locations for the interrupt service routines.

The M16C family, including the R8C, has two interrupt vector tables. One table has

fixed addresses which we will refer to as the fixed interrupt table. The other table can

be relocated by changing the value of the INTB core register, which is referred to as

the relocatable vector table.

8.1. Fixed vector table

The fixed vector table contains the vector addresses for the system type non-

maskable interrupts. These interrupts include:

Undefined instruction

Overflow

Break

Address Match

Single Step

WDT, Voltage Monitor and Oscillation Stop Detect

Address Break

A reserved vector

Reset

The Reset vector is located from 0FFFC to 0FFFD. The vector table

works down in memory (lower addresses) from there with each vector

location occupying four bytes. The fixed vector table is also unique since

part of this area has some other special features. Since each vector address

is actually only 3 bytes (24 bit addressing) the upper byte of many of the

vectors is used for special functions. It is worth noting since changing the

vector address in for these interrupts can change these values.

8.2. Shared functions in fixed vector table

8.2.1. Reset Vector - The upper byte (0ffff) of the Reset vector contains the

following special functions:

• Controlling whether WDT is on by default out of reset

• Controlling if WDT Count source protect (independent clock) is used

for WDT

• Controlling ROM code protect, which allows disabling parallel

programmers from accessing the flash

This memory location is referred to as the Option Function Select Register

(OSFR) and is discussed in section 19.3.2 of the hardware manual

8.2.2. All other fixed vectors except Break Vector

(Addresses 0FFDF, 0FFE3,OFFEB,OFFEF,OFFF3,0FFF7,OFFFB)

These 7 bytes make up the serial ID code which can be used to protect the

device from being erased or read using the serial flash interface. When

communicating with the device using the serial program interface the

serial interface must first be unlocked by sending down a ID code that

matches the one stored in these locations. Since these locations are not

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