Motorola Semiconductor Engineering Bulletin EB422 Enhanced

Freescale Semiconductor, Inc...
Engineering Bulletin
The ROM version of the PH8 also has an embedded version of a
PCbug11 talker. Embedding talkers in boot ROM has the advantage of
freeing memory in RAM (from where talkers normally run). The
disadvantage of such a talker is that there is no possibility to alter it if
required, for example, to change programming delay times. Also, due to
the limited memory available, the talker in the PH8 boot ROM does not
support the trace and breakpoint functions of PCbug11.
To use the boot ROM talker, the user must force a jump to the start of
the boot ROM talker. Listing 1. PCbug11 MC68HC(7)11PH8 Talker
Initialization Code shows the code required to perform the initialization.
Note that the boot ROM code only initializes the SCI vector by default;
the user should add further initialization to this talker file, if required. To
generate a machine readable talker, assemble the file using ASMHC11
with the ;B option. The .MAP shown in Listing 2. PCbug11 PH8 Talker
Map File tells PCbug11 where the talker code is. This must have the
same name as the talker file and both files require the use of PCbug11
version 3.40 or later.
Listing 1. PCbug11 MC68HC(7)11PH8 Talker Initialization Code
Listing 2. PCbug11 PH8 Talker Map File
Freescale Semiconductor, Inc.
M68HC11 Absolute Assembler Version 2.70C:\talkph8.ASC
1 A 0000 ORG $0
2 A 0000 7EBE40 start JMP $BE40
3 A END
Name of constant must not exceed 14 characters.
Value of constant must start in column 15 or higher.
talker_start $BE40 Talker code start address. (TLKRSTART)
talker_idle $BE5E Talker code idle loop address. (IDLE)
user_start $BE49 User’s reset entry into talker code. (USERSTART)
xirq_ujmp $00F2 Address of user’s XIRQ server address.
relocate_buf $00A0 PCbug11 workspace in MCU RAM
xirq_srv $BE61 Talker’s XIRQ service address. (SCISRV)
swi-srv $BE99 Talker’s SWI service address for break points. (SWISRV)
swi_idle $BE5E Talker’s SWI idle loop. (SWIIDLE)
null_srv $BE99 Talker RTI. (NULLSRV)
xirq_jmp $00F2 XIRQ vector.
swi_jmp $00F5 SWI vector.
cme_jmp $00FE COP clock monitor vector.
EB422
6 MOTOROLA
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