Need help with LDU inverter firmware download/upload

Topics concerning the Tesla front and rear drive unit drop-in board
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ajbessinger
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Need help with LDU inverter firmware download/upload

Post by ajbessinger »

Hi there folks,
I'm hoping to get a bit of assistance with an issue. I'm posting this on behalf of an acquaintance of mine named Shadi (who is from Jordan and doesn't speak English isn't very well). Shadi is working on a Mercedes B250e, which for those of you that don't know uses the same LDU as a Model S, but is set up for reverse rotation (reverse cut gears) and has an added parking pawl.

Unfortunately the inverter motherboard was damaged by a internal coolant leak, and will no longer function... The leak has been repaired, but since there were not many of these cars built, many of the parts for it are very difficult to get and he cannot source a replacement inverter or motherboard for it (especially in the part of the world he is in). He has access to another inverter motherboard (from a running car) that he's hoping to copy the firmware off of and transfer that to a Model S motherboard (which has the exact same part number and is not too hard to get).

Can anybody walk me though what he would need to connect to the JTAG ports on the boards, and what program would be needed to download and upload the firmware (if that's even possible)?

Thanks,
- Alex
amzoo
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Re: Need help with LDU inverter firmware download/upload

Post by amzoo »

I can't give any specific information for these boards, but I can hopefully give you more resources. You'll need to pull the memory from all the chips on the board and inject them to the new board, and even then it may not work. I'm not here to say what's possible so feel free to have fun exploring and figuring what works and doesn't work!

EVTV LDU Reverse Engineering
Note that one of the three chips identified thus far is the MicroSemi ProASIC3 A3P125. FPGA’s are Field Programmable Gate Arrays. Early computers were basically logic devices based on AND gates and OR gates and NAND gates and NOR gates and logic inverters etc. I guess modern computers are as well deep in the die. These chips provide massive numbers of them and allow you to write code to configure them in various ways. Picture a hardwired application specific computer. The advantage is that it is lightning fast at performing very defined logic and switching tasks. Tasks such as desaturation detection mayhaps?

The Texas Instruments chip set consists of the TMS320F2811PBQ Digital Signal Processor and the TMS320F280PAGQ Piccolo Microcontroller. Each are gratefully equipped with 14-pin JTAG connectors. We are more likely to find the code of interest of course in the Piccolo Microcontroller – the smaller of the three chips. This is the brains with the DSP and FPGA providing the brawn of the design.

The following steps are a summary from Embedded Bits on extracting firmware from JTAG
1. Find JTAG port
2. Attach JTAG adapter
3. Read Flash memory (assuming it's not locked)
Attachments
InverterBoardAnnotated.jpeg
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