NefMoto > Technical > Reverse Engineering > ME7 C167 clock change
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Author Topic: ME7 C167 clock change  (Read 7441 times)
zweistein
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« on: May 25, 2018, 12:44:26 AM »
Hello,

I am looking into reverse engineering of ME7.8.1 and ME7.8  DMEs.
My goal is to run the 996Turbo software on the later DME (ME7.8.1 is from 997 NA).
My special interest is in the CPU frequency of the C167 processor.
As I see from the data sheet the 3 pin P0H.7 - P0H.5  define the multiplier of the external clock .  External clock is 8 MHz on both units.
the ME7.8.1 has a multiplier of 5 (->40MHz) and the ME7.8 has a multiplier of 3 (->24MHz)

I would like to downgrade the ME7.8.1 to the 24MHz clock and I would need information on how to set the state of the 3 CPU pins correctly.

Do you know whether the pins are hardwired to logical high/low or are they connected to the 1MByte Flash memory?
I can see from the A2L files that there is a SYSTEM_CONSTANT "SY_FREQ_CPU" "40000" (or 24000)  for the 2 different DMEs.

Does this imply that the cpu multiplier is set via software and compiled into the binary?

Thanks for every hint I can get here

Andreas
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daniel2345
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« Reply #1 on: May 25, 2018, 02:26:04 AM »
I think you must read more about embedded devices.

How should the flash chip drive those pins? A flash chip has address lines as input and data lines as output.
Some more, but none to drive any pins via logic.

It is possible that those pins are driven by some gate latch IC which can be configured via running software.
But that would be extremely uncommon on Bosch units. Just trace the pins on pcb.

The constant in A2L is needed to calculate timed software functions (delays, filters) but is used only at compilation of code. Not at runtime.
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IamwhoIam
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« Reply #2 on: May 25, 2018, 05:13:30 AM »
You sound like you have no idea WTF you're talking about. 996TT ME7.8 uses C167, 997TT ME7.8.1 uses an ST10 CPU, along with internal memory. I can't even see WHY you'd want to run 996TT software in a ME7.8.1 ECU, when you could make appropriate changes to the ME7.8.1 software so that you can run a 996 turbo engine with it.
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zweistein
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« Reply #3 on: May 25, 2018, 07:45:29 AM »
I am talking about ME7.8.1 for NA 997  (inside 997 from 2005 to 2008)  not for TT!!! The TT would have a 2MB flash and other processsor,  the 997 NA DME has same processor, same flash, almost same periferials and the pin layout is almost identical.

Any helpful ideas?
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IamwhoIam
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« Reply #4 on: May 26, 2018, 04:34:31 AM »
Then you really have no idea what you're talking about. the C167 ME7.8 from the N/A 997 is called ME7.8min. The TT and GT2/GT2RS+some GT3/RS use ME7.8.1 which has an ST10 CPU and still a 29F800BB external flash. I have no idea where you're coming with 2mb flash from but from the overall confusion in your posts, it sounds like you don't even really know WHY you'd want to run 996TT software in a 997 NA ECU.
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zweistein
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« Reply #5 on: May 26, 2018, 08:17:20 AM »
@IamwhatIam:   why all this bashing from your side?  If you can't help answering my question you could also stay silent.
Best regards Andreas
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prj
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« Reply #6 on: May 26, 2018, 10:11:45 AM »
Quote from: zweistein on May 26, 2018, 08:17:20 AM
@IamwhatIam:   why all this bashing from your side?  If you can't help answering my question you could also stay silent.
Best regards Andreas

Your question is useless because you are basing it on false pretenses.
What you are suggesting is absurd.
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Jobard
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« Reply #7 on: September 08, 2018, 11:32:25 PM »
Hello i am interested by this subject.
Change the clock  could be usefull.

Regards
« Last Edit: September 08, 2018, 11:45:28 PM by Jobard » Logged
fluke9
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« Reply #8 on: December 31, 2019, 02:30:39 PM »
Quote from: zweistein on May 25, 2018, 12:44:26 AM
As I see from the data sheet the 3 pin P0H.7 - P0H.5  define the multiplier of the external clock .  External clock is 8 MHz on both units.
the ME7.8.1 has a multiplier of 5 (->40MHz) and the ME7.8 has a multiplier of 3 (->24MHz)

Resurrection of this thread as i just did this on a ME7.1 which was 24Mhz and i needed 20Mhz to run other software...

You just need to find the pull up or pull down resistors on P0H.7-5 and configure them in the way you need them,
but keep in mind the software you are going to flash needs sto have the correct SY_FREQ or else nothing will work as baudrates and other timer stuff is calculated compiletime via this macro.
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prj
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« Reply #9 on: February 04, 2020, 10:00:20 AM »
Uhmm... and it's pretty bold to assume that the IROM is not cpu freq dependent. Sorry for necro Tongue
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fluke9
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« Reply #10 on: February 05, 2020, 01:31:00 PM »
Quote from: prj on February 04, 2020, 10:00:20 AM
Uhmm... and it's pretty bold to assume that the IROM is not cpu freq dependent. Sorry for necro Tongue

Ooops double sorry for the necro.
Atleast the IROM i dumped had jnb on some clock register bits, but well i had to disable irom for my image to run so i did not look into details...
You might be right that the VAG irom is clock dependant.
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