Freescale Semiconductor, Inc.
EPROM/OTPROM (PROM)
9.4.2 Verify PROM Contents
The verify PROM contents routine is normally run automatically after the
PROM is programmed. Direct entry to this routine causes the PROM
contents of the MCU to be compared to the contents of the external
memory locations of the EPROM at the same addresses.
To invoke the verify PROM contents routine of the MCU, take these
steps:
1. Set switch 1 in the ON position (restores VDD).
2. Connect VPP to VDD.
3. Set switches S3, S4, and S6 in the OFF position.
4. Set S5 in the ON position.
5. Set switch 2 in the OUT position (routine is activated).
The red LED is not illuminated during this routine, since no
programming takes place. If verification fails, the routine halts with
the failing address in the external memory bus. When the green
LED is illuminated, verification is completed successfully and the
routine is finished.
6. Set switch 2 in the RESET position.
At this point, if another routine is to be performed on the MCU being
programmed, the user can set switches S3, S4, S5, and S6 to the
positions necessary to select the next routine and move switch S2 to the
OUT position to start the routine. If no other routine is to be performed,
remove VDD from the board and remove the MCU from the programming
socket.
9.4.3 Secure PROM
The secure PROM routines are used after the PROM is successfully
programmed and verified. Only the SEC bit of the option register
($1FDF) is programmed, but VPP is necessary. Once this bit is
programmed, PROM is secure and can be neither verified nor dumped.
Technical Data
112
MC68HC705C8A — Rev. 3
EPROM/OTPROM (PROM)
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