μPD75P308

3.3 PROGRAM MEMORY READ PROCEDURE

The contents of the program memory can be read in the following procedure.

(1)Ground the unused pins through pull-down resistors. The X1 pin must be low.

(2)Supply 5 V to the VDD and VPP pins.

(3)Wait for 10 microseconds.

(4)Set program memory address 0 clear mode.

(5)Supply 6 V to the VDD pin and 12.5 V to the VPP pin.

(6)Set program inhibit mode.

(7)Set verify mode. Data of each address is sequentially output each time a clock pulse is input to the X1 pin four times.

(8)Set program inhibit mode.

(9)Set program memory address 0 clear mode.

(10)Change the voltages of VDD and VPP pins to 5 V.

(11)Turn off the power supply.

Steps (2) to (9) are illustrated below.

VPP

VPP

VDD

VDD+1

VDD

VDD

X1

 

 

P40-P43

Data output

Data output

P50-P53

 

 

MD0

(P30)

MD1

(P31)

MD2

(P32)

MD3

(P33)

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NEC PD75P308 user manual Program Memory Read Procedure, MD2