
Technical Data
MC68HC11E Family
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Rev. 4
94
Operating Modes and On-Chip Memory
MOTOROLA
Operating Modes and On-Chip Memory
4.5.2 Programming the EPROM with Downloaded Data
When using this method, the EPROM is programmed by software while
in the special test or bootstrap modes. User-developed software can be
uploaded through the SCI or a ROM-resident EPROM programming
utility can be used. The 12-volt nominal programming voltage must be
present on the XIRQ/V
PPE
pin. To use the resident utility, bootload a
3-byte program consisting of a single jump instruction to $BF00. $BF00
is the starting address of a resident EPROM programming utility. The
utility program sets the X and Y index registers to default values, then
receives programming data from an external host, and puts it in EPROM.
The value in IX determines programming delay time. The value in IY is
a pointer to the first address in EPROM to be programmed
(default = $D000).
When the utility program is ready to receive programming data, it sends
the host the $FF character. Then it waits. When the host sees the $FF
character, the EPROM programming data is sent, starting with the first
location in the EPROM array. After the last byte to be programmed is
sent and the corresponding verification data is returned, the
programming operation is terminated by resetting the MCU.
For more information, Motorola application note AN1060 entitled
M68HC11 Bootstrap Mode
has been included at the back of this
document.
4.5.3 EPROM and EEPROM Programming Control Register
The EPROM and EEPROM programming control register (PPROG)
enables the EPROM programming voltage and controls the latching of
data to be programmed.
For MC68HC711E9, PPROG is also the EEPROM programming
control register.
For the MC68HC711E20, EPROM programming is controlled by
the EPROG register and EEPROM programming is controlled by
the PPROG register.