NEC PD754144 User Manual

Page 189

CHAPTER 7 INTERRUPT AND TEST FUNCTIONS

189

User’s Manual U10676EJ3V0UM

Figure 7-2. Interrupt Vector Table

MBE

Address

0002H

0004H

0006H

0008H

000AH

000CH

000EH

RBE

INTBT start address (higher 4 bits)

INTBT start address (lower 8 bits)

INT0 start address (higher 4 bits)

INT0 start address (lower 8 bits)

INTT0 start address (higher 4 bits)

INTT0 start address (lower 8 bits)

INTT1, INTT2 start address (higher 4 bits)

INTT1, INTT2 start address (lower 8 bits)

INTEE start address (higher 4 bits)

INTEE start address (lower 8 bits)

The priority column in Table 7-1 indicates the priority according to which interrupts are executed if two or more

interrupts occur at the same time, or if two or more interrupt requests are held pending.

Write the start address of interrupt servicing to the vector table , and the set values of MBE and RBE during interrupt

servicing. The vector table is set by using an assembler quasi directive (VENTn: n = 1, 2, or 5 to 7).

Example Setting of vector table of INTBT

VENT1 MBE=0, RBE=0, GOTOBT

↑

<1>

<2>

<3>

<4>

<1> Vector table of address 0002

<2> Setting of MBE in interrupt servicing routine

<3> Setting of RBE in interrupt servicing routine

<4> Symbol indicating start address of interrupt servicing routine

Caution The contents described as the operand of VENTn (n = 1, 2, or 5 to 7) (MBE, RBE, or start address)

are stored in the vector table address at address 2n.

Example Setting of vector tables of INTBT and INTT0

VENT1 MBE=0, RBE=0, GOTOBT; INTBT start address

VENT5 MBE=0, RBE=1, GOTOT0; INTT0 start address

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