|
Title: ME7.5 Question - regarding the am29f800bb chip Post by: wchering on October 20, 2020, 02:23:11 AM Hi guys, I have a question in relation to the am29f800bb flash chip on a ME7.5 ECU.
Does pin 24 on this chip serve any other purpose than enabling the ECU to enter boot mode? I recently bricked my ECU and have repaired it in the past, but this time I may have screwed up the contact for pin 24 where it sits on the board. From what I can see, the trace for pin 24 only leads to a solder pad on the board but I am no longer seeing continuity between the pin and pad via my multimeter. The rest of the pins have continuity to where the traces lead for the chip, but I am just wondering if the pin you are required to ground for boot mode, pin 24, serves any other purpose. I am hoping I can keep this ECU as a backup if it remains fully functional regardless of my bad soldering job :o I am currently awaiting the arrival of a breakout cable which will allow me to bench the ECU. Thanks in advance! Title: Re: ME7.5 Question - regarding the am29f800bb chip Post by: timus on October 20, 2020, 04:43:57 AM It's actually DQ4 pin, which means it's data bus bit 4, ecu will most likely not work without it, because data will be corrupted.
Title: Re: ME7.5 Question - regarding the am29f800bb chip Post by: nyet on October 20, 2020, 11:36:46 AM The CPU end of that pin matters for bootmode, not the chip side.
That said, it is *ALSO* used as a data/addressing pin between the CPU and the flash. There are a lot of misunderstandings over how this pin works, since it requires a bit of microprocessor design knowledge to understand its function. It is a bi directional pin. During normal operations, it is used by the cpu as a one of the data bits when reading/writing. During boot, the *CPU* samples this pin (long before the flash is accessed for anything else, regardless if a flash is there or not) to determine if the cpu should go into boot mode or not. Title: Re: ME7.5 Question - regarding the am29f800bb chip Post by: wchering on October 21, 2020, 02:31:45 AM The CPU end of that pin matters for bootmode, not the chip side. That said, it is *ALSO* used as a data/addressing pin between the CPU and the flash. There are a lot of misunderstandings over how this pin works, since it requires a bit of microprocessor design knowledge to understand its function. It is a bi directional pin. During normal operations, it is used by the cpu as a one of the data bits when reading/writing. During boot, the *CPU* samples this pin (long before the flash is accessed for anything else, regardless if a flash is there or not) to determine if the cpu should go into boot mode or not. Thank you for this information!!! Initially this problem started by writing a file with a bad checksum to the ECU via MPPS v13. Since this point, the car would not start and MPPS would report 'ECU not found'. With that said, my breakout harness arrived and I am able to get the ECU into bootmode by shorting pin 24. I am also able to do a full read via galletto 1260, and have dumped the ecu.bin successfully. This makes me think pin 24 is still intact. But I am having issues writing... Is there any hope for this ECU? I have attached pics of my attempts to write the flash. Here is the log from Galletto 1260 when trying to write: WRITING ECU Writing InitilizationOK Seed key... OK Erasing...OK Start writing...error writing (https://lh4.googleusercontent.com/3jZOyW1ABuqPwsdsVmbh2nDbNUYUSbo_aWuKdX4RwWB0UYkbLsQmVk3IDx3ZDwHSFLiJ3yJAFcRYeA=w1920-h937-rw) (https://lh6.googleusercontent.com/COgVlbBWgOvttAYoZdGkcAQPuHk_AvapTzw6IfpG5Dku0cl3IC6ToSGdJZqRs9rfZgHiVD0F-1sszw=w1920-h937-rw) (https://lh5.googleusercontent.com/8tgJXHG8ooe5mqNWLGwqM5OPR-eT4hLxwSbQJrG4mHRgR9y8TKyL_j9pKap6m3x11tSFTT7jUsWKmw=w1920-h937-rw) Title: Re: ME7.5 Question - regarding the am29f800bb chip Post by: BlackT on October 21, 2020, 02:43:17 AM Buy new 29F800BB , you can find it on ebay for few bucks
|