NEC PD78P214 Manuale Utente

Chapter 2 Pin Functions

(8) ASTB (address strobe): Output

Timing signal output used for latching addresses externally to enable access to external memory.

(9) EA (external access): Input

Control signal input used for switching the program memory from the internal ROM to the external memory.
When this signal is high, the internal ROM is accessed. When low, the external memory is accessed in ROM-
less mode. In the case of the

µPD78212, µPD78214, and µPD78P214, always apply a high-level signal to this

pin. In the case of the

µPD78213, apply a low-level signal.

(10) X1 and X2 (crystal)

Pins for connecting the crystal used for internal clock oscillation. When an external clock signal is supplied,
apply it to pin X1. Also, apply the signal having the inverted phase of this clock signal to pin X2.

(11) RESET (reset): Input

Low-active reset input.

(12) AV

REF

Input of the reference voltage and power for the A/D converter.

(13) AV

A/D converter ground.

(14) V

Main power input. Connect all V

pins to the power.

(15) V

Ground. Connect all V

pins to the ground.

(16) NC (non-connection)

Not connected inside the chip.

2.2.2 PROM Programming Mode (for the

PD78P214)

(1) P20/NMI: Input

Input used for setting the

µPD78P214 to PROM programming mode. When a voltage of 12.5 V is applied to

this pin and the RESET pin goes low, the

µPD78P214 enters PROM programming mode.

(2) RESET: Input

Input used for setting the

µPD78P214 to PROM programming mode. When a low-level signal is applied to this

pin and a voltage of 12.5 V is applied to the P20/NMI pin, the

µPD78P214 enters PROM programming mode.

(3) A0 to A14 (address bus): Inputs

Address bus used for the internal PROM (0000H to 3FFFFH). Apply a low-level signal to pin A14.

(4) D0 to D7 (data bus): Inputs/outputs

Data bus, through which programs are read or written to and from the internal PROM.

(5) CE (chip enable): Input

Enable signal input for the internal PROM. When this signal is active, programs can be either written or read.

(6) OE (output enable): Input

Read strobe signal input for the internal PROM. When this input goes active while the CE is low, one byte of
the program at the address specified by pins A0 to A14 in the internal PROM is read through pins D0 to D7.

(7) V

(programming power supply)

Power supply for writing programs. When the CE goes low while the V

is 12.5 V and the OE is high, the data

on pins D0 to D7 is written into the internal PROM at the address specified by pins A0 to A14.

(8) V

Main power input.