NEC uPD78056Y - Manual (Page 552)

552
CHAPTER 26
µ
PD78P054, 78P058
26.4 PROM Programming
The
µ
PD78P054 and 78P058 incorporate a 32-Kbyte and 60-Kbyte PROM as program memory, respectively.
To write a program into the
µ
PD78P054 or 78P058 PROM, make the device enter the PROM programming mode
by setting the levels of the V
PP
and RESET pins as specified. For the connection of unused pins, see paragraph
(2) “PROM programming mode” in section 1.5 or 2.5 Pin Configuration (Top View).
Caution In case of the
µ
PD78P054, write the program in the range of addresses 0000H to 7FFFH (specify
the last address as 7FFFH.)
In case of the
µ
PD78P058, write the program in the range of addresses 0000H to EFFFH (specify
the last address as EFFFH.)
The program cannot be correctly written by a PROM programmer which does not have a write
address specification function.
26.4.1 Operating modes
When +5 V or +12.5 V is applied to the V
PP
pin and a low-level signal is applied to the RESET pin, the
µ
PD78P054
and
µ
PD78P058 are set to the PROM programming mode. This is one of the operating modes shown in Table 26-
6 below according to the setting of the CE, OE, and PGM pins.
The PROM contents can be read by setting the read mode.
Table 26-6. PROM Programming Operating Modes
Pin
Operating mode
Page data latch H L H Data input
Page write H H L High impedance
Byte write L H L Data input
Program verify L L H Data output
L
×
H H
×
L L
Read L L H Data output
Output disabled +5 V +5V L H
×
High impedance
Standby H
Ч Ч
High impedance
Remark
×
: L or H
(1) Read mode
Read mode is set by setting CE to L and OE to L.
(2) Output disable mode
If OE is set to H, data output becomes high impedance and the output disable mode is set.
Therefore, if multiple
µ
PD78P054s or 78P058s are connected to the data bus, data can be read from any one
device by controlling the OE pin.
RESET V
PP
V
DD
CE OE PGM D0-D7
Program inhibit High impedance
+12.5 V +6.5 V