Help with 6816 chip and ROM image

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Moderator: Freon

Help with 6816 chip and ROM image

Postby prana » Sat Jun 02, 2007 5:16 am

Few questions (chip is 68HCY15)

1. what is the offset at which the ROM is based/loaded at ? The first segment is RAM. At what offset would the downloaded DENSO image be the 'read' image that we see when we download the ROM ?

2. In the A4TH100H for example, the AVCS elements as here
<table name="Intake Cam Advance Angle (AVCS)" address="2a621">
<table name="X" address="2a603" elements="14" />
<table name="Y" address="2a5e0" elements="17" />


A. These addresses can't be relative to the image itself can it ? The image is only reads to 0x27ff0, how does it reach 2a621 ? I'm assuming these are not absoute addresses ?

B. How did you determine what offsets relates to each map ? Did you reverse the entire ROM to follow the numerous simultaneous threads ? How did you figure out which interrupt, I/O etc relates to the different entry points ? eg 0x220, 0x240. Is this information available anywhere to share ?

Cheers.
prana
 
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Postby Freon » Sat Jun 02, 2007 12:06 pm

I believe the XML we use to edit is always absolute addressing. However, that address may be based on a 192kB file, not a 160kB.

There is only one real size for the 68hc16 flash image (160kB) but it can be expanded to 192kB to account for some address space the ECU uses. I don't know the details of this off the top of my head but you might try searching old threads here or reading through a technical document on the exact CPU model you have.
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Postby radsdau » Tue Jun 05, 2007 3:50 pm

I think it works like this. The memory layout is:
128k Flash
32k hole (including 8k RAM)
32k Flash

Total flash is only 160k, but to the HC16, it 'spans' 192k. The 32k in the middle is not flash so can be ignored.
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Postby prana » Wed Jun 06, 2007 3:07 am

yup that makes sense, as the ID stamp is exactly at 0x200 as the XML definition, but the map offsets aren't. I have been looking through the site but I could not find anything of relevance, until the above post. Do you know where exactly, or what exact size the 'hole' is ? Is it exactly 32768 bytes ?
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Postby radsdau » Wed Jun 06, 2007 4:15 pm

$20000-$27FFF is the hole.
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