NEC PD78214 - Manual (Page 60)

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Chapter 2 Pin Functions
2
(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
SS
A/D converter ground.
(14) V
DD
Main power input. Connect all V
DD
pins to the power.
(15) V
SS
Ground. Connect all V
SS
pins to the ground.
(16) NC (non-connection)
Not connected inside the chip.
2.2.2 PROM Programming Mode (for the
µPD78P214)
(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
PP
(programming power supply)
Power supply for writing programs. When the CE goes low while the V
PP
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
DD
Main power input.