NEC PD78P214 Manuale Utente

401

Chapter 17   Programming for The 

µ

PD78214

The contents of PROM can be read out to the external data bus (D0 to D7) by following the procedure below:

(1) Fix the RESET pin to the low level.  Apply +12.5 V to pin NMI.  Handle unused pins as described in Section 1.3.2.

(2) Apply +5 V to the V

DD

 and V

PP

 pins.

(3) Input the address of the data to be read into the A0 to A14 pins.

(4) Set read mode.

(5) Output the data on the D0 to D7 pins.

Fig. 17-3 is the timing chart for steps (2) to (5).

Write failure (25th)

Write success

> Last address

Last address

Write failure (up to 24th)

(1)

(6)

(10)

(7)

(2)

(3)

(4)

(5)

(9)

<

Defective device

Start writing 

Apply power supply voltage

Set an initial address

Verify mode

Last address

Write completes

Increment the address

Input a program pulse

Input write data

(8)

Additional write (3X ms pulse)

X:  Number of times 
     writing is repeated