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Special
Port Pin
Function
Signal
P1.2:1,
PBUS
P4.7:5,
P3.7:0
—
EA#
—
V
PP
15.7 ENTERING PROGRAMMING MODES
To execute programs properly, the device must have these minimum hardware connections:
XTAL1 driven, unused input pins strapped, and power and grounds applied. Follow the operating
conditions specified in the datasheet. Place the device into programming mode by applying V
voltage (+12.5 V) to EA# during the rising edge of RESET#.
15.7.1 Selecting the Programming Mode
The PMODE (P0.7:4) value controls the programming mode. PMODE is sampled on the rising
edge of RESET#. You must reset the device to switch programming modes. Table 15-6 lists the
PMODE value for each programming mode. All other PMODE values are reserved.
PROGRAMMING THE NONVOLATILE MEMORY
Table 15-5. Pin Descriptions (Continued)
Program-
Type
ming
Mode
I/O
Auto
Address/Command/Data Bus
ROM-
During auto programming and ROM-dump, ports 3 and 4
dump
serve as a regular system bus to access external
memory.
P4.6 and P4.7 are left unconnected; P1.2 and P1.1 serve
as the upper address lines.
I
All
External Access
Controls program mode entry. If EA# is at V
the rising edge of RESET#, the device enters
programming mode.
EA# is sampled and latched only on the rising edge of
RESET#. Changing the level of EA# after reset has no
effect.
I
All
Programming Voltage
During programming, the V
(V
PP
fication can damage the device.
Table 15-6. PMODE Values
PMODE Value
Programming Mode
(Hex)
0
Serial port programming
5
Slave programming
6
ROM-dump
C
Auto programming
Description
pin is typically at +12.5V
PP
voltage). Exceeding the maximum V
voltage on
PP
voltage speci-
PP
PP
15-13
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