
Operating Modes and On-Chip Memory
EPROM/OTPROM
M68HC11E Family — Rev. 5
Data Sheet
MOTOROLA
Operating Modes and On-Chip Memory
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53
Using the on-chip EPROM/OTPROM programming feature requires an external 
12-volt nominal power supply (V
PPE
). Normal programming is accomplished using 
the EPROM/OTPROM programming register (PPROG). 
PPROG is the combined EPROM/OTPROM and EEPROM programming register 
on all devices with EPROM/OTPROM except the MC68HC711E20. For the 
MC68HC711E20, there is a separate register for EPROM/OTPROM programming 
called the EPROG register. 
As described in the following subsections, these two methods of programming and 
verifying EPROM are possible:
1.
Programming an individual EPROM address
2.
Programming the EPROM with downloaded data
2.4.1  Programming an Individual EPROM Address 
In this method, the MCU programs its own EPROM by controlling the PPROG 
register (EPROG in MC68HC711E20). Use these procedures to program the 
EPROM through the MCU with:
The ROMON bit set in the CONFIG register
The 12-volt nominal programming voltage present on the XIRQ/V
PPE
 pin
The IRQ pin must be pulled high.
NOTE:
Any operating mode can be used. 
This example applies to all devices with EPROM/OTPROM except for the 
MC68HC711E20. 
EPROG
LDAB
STAB
#$20 
$103B
Set ELAT bit in (EPGM = 0) to enable
EPROM latches. 
Store data to EPROM address 
STAA
LDAB
STAB
$0,X
#$21 
$103B
Set EPGM bit with ELAT = 1 to enable
EPROM programming voltage 
Delay 2–4 ms 
Turn off programming voltage and set 
to READ mode 
JSR
CLR
DLYEP
$103B
This example applies only to MC68HC711E20. 
EPROG
LDAB
STAB
#$20 
$1036
Set ELAT bit (EPGM = 0) to enable 
EPROM latches. 
Store data to EPROM address 
STAA
LDAB
STAB
$0,X
#$21 
$1036
Set EPGM bit with ELAT = 1 to enable 
EPROM programming voltage 
Delay 2–4 ms 
Turn off programming voltage and set 
to READ mode 
JSR
CLR
DLYEP
$1036
F
Freescale Semiconductor, Inc.
n
.