Ucd3138A64 Boot Rom Execution After Power-On/Reset; Checksums Used By Ucd3138128 Boot Rom Program; Ucd3138128 And Ucd3138128A - Texas Instruments UCD3138 Technical Reference Manual

Boot ROM for the Other Members of the UCD3138 Family
Figure 13-4. UCD3138A64 Boot ROM Execution After Power-on/Reset
Figure 13-4 is a flowchart showing the order in which the ROM verifies the integrity of the program flash
contents using the different checksums.
The branch instruction check at the beginning prevents the checksum program from trying to verify the
integrity of an empty block of memory. Otherwise a block filled with zeroes would pass the checksum test.
The UCD3138A64 doesn't have ROM support for putting 2 separate programs into flash, one in each flash
block. This can still be done, however, using a boot flash program. Or the program in block 0 can be a
fixed program, which checks the program in block 1 and jumps to it if appropriate.

13.8.3 UCD3138128 and UCD3138128A

The UCD3138128 uses checksums to verify the integrity of the first 2kB, 32kB and 64kB of program flash
just like the UCD3138A64. It also has checksums to verify the second 64kB and for the full 128kB of
program flash. This provides Boot ROM support for 2 independent versions of the firmware in a single
device. The checksums and their locations are shown in
Table 13-6. Checksums Used by UCD3138128 Boot ROM Program
Checksum Location
0x007F8
0x07FF8
0x0FFF8
0x1FFF8
450
Boot ROM and Boot Flash
Table
Purpose
Checksum for 2kB boot in program flash 0
Checksum for 32kB program in program flash 0
Checksum for 64kB program in program flash 0 and 1
Checksum for 64kB program in program flash 2 and 3 or
Checksum for 128kB program in program flash 0, 1, 2 and 3
Copyright © 2016, Texas Instruments Incorporated
13-6.
SNIU028A – February 2016 – Revised April 2016
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