Prom Programming Mode - NEC PD78212 User Manual

(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 µ PD78212, µ PD78214, and µ PD78P214, always apply a high-level signal to this
pin. In the case of the µ PD78213, 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
(15) V
SS
Ground. Connect all V
(16) NC (non-connection)
Not connected inside the chip.
2.2.2 PROM Programming Mode (for the µ PD78P214)
(1) P20/NMI: Input
Input used for setting the µ PD78P214 to PROM programming mode. When a voltage of 12.5 V is applied to
this pin and the RESET pin goes low, the µ PD78P214 enters PROM programming mode.
(2) RESET: Input
Input used for setting the µ PD78P214 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 µ PD78P214 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)
PP
Power supply for writing programs. When the CE goes low while the V
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.
pins to the power.
DD
pins to the ground.
SS
Chapter 2 Pin Functions
is 12.5 V and the OE is high, the data
PP
2
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