[help needed] obd1 honda/gm daughterboard. 27sf512 EEPROM emulator

Hardware inside and outside of the ECU
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texasgdp754
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Joined: Mon Nov 18, 2019 11:48 pm

obd1 honda/gm daughterboard. 27sf512 EEPROM emulator

Post by texasgdp754 »

Hello to all,

I have been lurking and following for a few years. This will be my first post. I would like to say rusefi open source platform has been great for the diy tuning efi community.

I have considered spinning rusefi board with pnp connector for obd1 honda. However most folks seem to be perfectly content with modified honda rom and using one of the available options for a daughterboard to do real time programming. Hardware can be had from moates,hondata,or cobrartp. Hondata software can only be used with their hardware. Honda tuning suite, EcTune, Neptune,BMtune,crome are all software options .
Honda tuning suite is a free and powerful program for anyone to use.

To this day there is not any open source options for an eeprom emulator to enable real time tuning function. I have designed a board for 27c256 or 27sf512 eeprom emulation. This device is intended for use in obd1 honda for me. It also could be used in Motronic, Jetronic, Siemens MS40.1, GM, DSM (BMW, Audi, Porsche, GM, Mitsubishi, Fiat, Volvo, etc.). I would like to share this design public so anyone with soldering skills can order a board and assemble it.

I am posting to seek help in writing firmware for it I have little to no experience in software development. The mcu is atmega64a. 2 sram chips 128kx8 ly621024ll-55. 2 channel uart ftdi ft2232d. The moates ostrich and xtronics romulator both have open hardware protocols. I would like our device to use moates ostrich and or romulator protocols as to allow easy integration with existing tuning software's.

I am posting from my mobile phone right now. I will update post shortly to include schematic and hardware protocols.

Image

Image
Image

updated 11/25 with schematic and hardware protocols for anyone who would like to review and give feedback/support.
Attachments
Schematic_RTP BOARD V2 TSOP_Sheet_1 tsop RTP_20191125004659.pdf
(221.02 KiB) Downloaded 156 times
Moates Hardware Protocols v19.xls
(74.5 KiB) Downloaded 124 times
Last edited by texasgdp754 on Mon Nov 25, 2019 7:12 am, edited 3 times in total.

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AndreyB
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Re: obd1 honda daughterboard. 27sf512 eeprom emulator

Post by AndreyB »

Let me quote some smart people, I do not really have to add much :(

960 12:50 PM
Everyone seems to just do hardware, but the fact is the hardware are way ahead of software at this point

Simon - Orchardperformance 12:52 PM
Sure, I can only do a little on the software though
That's the trouble, we have a lot of skilled people but only a few C++ programmers
and not enough test time

960 12:53 PM
Yes.. So we have a huge lack of programmers
https://rusefi.com/s/howtocontribute
very limited telepathic abilities - please post logs & tunes where appropriate - http://rusefi.com/s/questions
my skype is arro239

texasgdp754
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Re: obd1 honda daughterboard. 27sf512 eeprom emulator

Post by texasgdp754 »

Unfortunately I'm well aware... same reason there is hardware but not software for knock detection

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AndreyB
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Re: obd1 honda daughterboard. 27sf512 eeprom emulator

Post by AndreyB »

texasgdp754 wrote:
Tue Nov 19, 2019 4:46 am
Unfortunately I'm well aware... same reason there is hardware but not software for knock detection
Also gasoline direct injection, also... The list goes on.
https://rusefi.com/s/howtocontribute
very limited telepathic abilities - please post logs & tunes where appropriate - http://rusefi.com/s/questions
my skype is arro239

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kb1gtt
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Re: obd1 honda daughterboard. 27sf512 eeprom emulator

Post by kb1gtt »

Welcome along, and thanks for the post.

I agree that software resources are our issue here. There are is also the issue that the software people need to have a development platform to develop with, which makes it harder to get software resources available. AKA you need to have an extra car, and most software developers live in, or near city's which makes it difficult to have one car, let alone multiple extra cars.

With Frankenso the goal has been to be very flexible, which allows PNP on some specific applications, but also with some fairly small modifications it can be used on most port injected engines. The flexibility has been key in getting software resources available for the overall picture. I fear that this EEPROM board is a very limited niche group of people who are not software oriented. This will likely make it difficult to get software resources interested in it.

At the end of the day, I think most people don't care if it's an EEPROM inside the original ECU, or different ECU. I think they care about features, labor hours to implement and $ costs.

We have a long list of features we are trying to add. Is there a chance you could be interested in one of these other efforts? I see key issues with today's DIY stuff are the lack of transmission controls, poor ETB, and direct injection applications. There are lots of low cost cars out there now which these technologies. Those technologies are beneficial at the race track.
Welcome to the friendlier side of internet crazy :)

monty
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Joined: Mon Oct 14, 2019 6:56 pm

Re: obd1 honda daughterboard. 27sf512 eeprom emulator

Post by monty »

hi, it is long ago solved, buy ostrich emulator, datalog cable usb to ttl and any of the above mentioned programs, crome, neptune and realtime debugging works .I don't understand why doing something long ago developed on such old ecus ..it would be better to make a board for rusefi as a direct replacement for the old obd 1 ecu(p28,P30 etc), where it would not be as complicated as frankenso board.

monty
Posts: 3
Joined: Mon Oct 14, 2019 6:56 pm

Re: obd1 honda daughterboard. 27sf512 eeprom emulator

Post by monty »

right now I try to put frankenso plug and play on a my car honda hrv in moments of free time, but there is a problem at start when it is somehow disturbed, it shows the speed 14t -17t rpm,but if I only spin the distributor drill it reads pulses reliably up to 2t rpm,to max rpm drill ...

texasgdp754
Posts: 17
Joined: Mon Nov 18, 2019 11:48 pm

Re: obd1 honda daughterboard. 27sf512 eeprom emulator

Post by texasgdp754 »

sure it was solved long ago monty....as were standalone efi controllers... , doesnt mean others shouldnt want to complete the same thing on their own in a diy manner for much less money.Anyone can go and buy an Ostrich or Hondata. Just like anyone can go and buy A haltech, aem, link, ecumaster, etc. In the case of my hardware rather than spend $200 on an ostrich, one could build a board for $15.
I posted up schematic and protocols to original post. Feel free to critique the Schematic .
I understand that this is "older technology" . But in reality is a pretty simple device that could be easily made and would open the door to Live tuning to alot of people and come in at a cost of less than the cheapest chip burner currently on the market. I am not looking to monetize anything. Simply looking to contribute to the open source development of efi systems in general. My BOM is even friendly to be used with jlcpcb assembly service .

texasgdp754
Posts: 17
Joined: Mon Nov 18, 2019 11:48 pm

Re: obd1 honda daughterboard. 27sf512 eeprom emulator

Post by texasgdp754 »

kb1gtt wrote:
Tue Nov 19, 2019 7:48 am
Welcome along, and thanks for the post.

I agree that software resources are our issue here. There are is also the issue that the software people need to have a development platform to develop with, which makes it harder to get software resources available. AKA you need to have an extra car, and most software developers live in, or near city's which makes it difficult to have one car, let alone multiple extra cars.

With Frankenso the goal has been to be very flexible, which allows PNP on some specific applications, but also with some fairly small modifications it can be used on most port injected engines. The flexibility has been key in getting software resources available for the overall picture. I fear that this EEPROM board is a very limited niche group of people who are not software oriented. This will likely make it difficult to get software resources interested in it.

At the end of the day, I think most people don't care if it's an EEPROM inside the original ECU, or different ECU. I think they care about features, labor hours to implement and $ costs.

We have a long list of features we are trying to add. Is there a chance you could be interested in one of these other efforts? I see key issues with today's DIY stuff are the lack of transmission controls, poor ETB, and direct injection applications. There are lots of low cost cars out there now which these technologies. Those technologies are beneficial at the race track.
I would like to spend some time on Electronic Throttle Body. Time to go to the Junkyard and pull some parts off a newer truck. My test mule is stock cable driven 2000 silverado 5.3l lm7. would like to convert to etb and rusefi.

monty
Posts: 3
Joined: Mon Oct 14, 2019 6:56 pm

Re: obd1 honda daughterboard. 27sf512 eeprom emulator

Post by monty »

texasgdp754 wrote:
Mon Nov 25, 2019 7:03 am
sure it was solved long ago monty....as were standalone efi controllers... , doesnt mean others shouldnt want to complete the same thing on their own in a diy manner for much less money.Anyone can go and buy an Ostrich or Hondata. Just like anyone can go and buy A haltech, aem, link, ecumaster, etc. In the case of my hardware rather than spend $200 on an ostrich, one could build a board for $15.
I posted up schematic and protocols to original post. Feel free to critique the Schematic .
I understand that this is "older technology" . But in reality is a pretty simple device that could be easily made and would open the door to Live tuning to alot of people and come in at a cost of less than the cheapest chip burner currently on the market. I am not looking to monetize anything. Simply looking to contribute to the open source development of efi systems in general. My BOM is even friendly to be used with jlcpcb assembly service .
Yes, I understand, I just do not find it profitable to invest money and skills in a project that works with outdated hardware. I have been dealing with only five malfunctioning or non-standard functioning factory ecu, p28, p30. It's just 25 years old .... mostly I use Vems, but it needs to adjust the wiring harness, so I'm interested in rusefi where it could be p & p. Plus the possibility of cop, wb, knock which the factory ecu does not offer.So I think the original idea is more reasonable :D

b18libra
Posts: 2
Joined: Thu Jan 16, 2020 10:35 pm

Re: obd1 honda/gm daughterboard. 27sf512 EEPROM emulator

Post by b18libra »

Hi texasgdp754, did you get any further with this design? I saw you posted to pgmfi for assistance but it's a bit dead over there.

I'm trying to comprehend your sch but it's a bit hard to build a mental image with use of all the interpage connectors.
Please can you draw a high level block diagram of this schematic? I'd be expecting to see something like this:
Image
I've setup a Github repo here with the draw.io block diagram.
The main point of the dual memory architecture is the ability to isolate and modify one SRAM at a time with the MCU. As long as we manage the bus switching by being aware of modified addresses it should be seemless and the ECU will encounter minimal glitches on the data lines.

I've noticed an existing open source design can be found here but it's got a number of flaws.
1. Being a single chip design it's always[1] going to interrupt memory accesses.
2. The FW uses a very ham fisted method of yanking the memory from the ECU and hogging it for many cycles (>2.5us).
A user on the pgmfi forum reports a CEL light and engine stuttering, which is no surprise considering the above.
Regardless of these short comings the code base for this project provides a good reference implementation for the ROMulator protocol.

[1] Regarding a single memory chip architecture: Some napkin maths shows neither a AVR or M3 cortex could jump to a ISR in less than 150ns, so syncing MCU memory accesses to avoid collisions isn't feasible. The original EEPROM is specced for 70ns read accesses, it may be possible to sync accesses by using 25ns SRAM and an exotic FPGA design.

If anyone has information on the ECU CPU that would be a helpful, particularly clock speed and setup and hold times for the memory accesses.

texasgdp754
Posts: 17
Joined: Mon Nov 18, 2019 11:48 pm

Re: obd1 honda/gm daughterboard. 27sf512 EEPROM emulator

Post by texasgdp754 »

Revised the schematic where I had some errors. Re spun the PCB using more common sram chip. Will update thread once I've got some boards in hand and done some testing.

B18libra : if your capable of firmware development and willing to help I'd be happy to take the time to provide the info you asked for. Otherwise to be candid I won't spend the time to make the block diagram. Thanks in advance.

kalisto2002
Posts: 1
Joined: Thu Feb 06, 2020 9:42 am

Re: obd1 honda/gm daughterboard. 27sf512 EEPROM emulator

Post by kalisto2002 »

texasgdp754 wrote:
Mon Feb 03, 2020 1:21 am
Revised the schematic where I had some errors. Re spun the PCB using more common sram chip. Will update thread once I've got some boards in hand and done some testing.

B18libra : if your capable of firmware development and willing to help I'd be happy to take the time to provide the info you asked for. Otherwise to be candid I won't spend the time to make the block diagram. Thanks in advance.
Hey there. If you are looking for help with firmware. I am one of the programmers for Honda Tuning Suite(Shameless plug https://facebook.com/hondatuningsuite )
And I would totally be down to help you out with the firmware side of things. send a message to the page on facebook, and we can talk more :)

b18libra
Posts: 2
Joined: Thu Jan 16, 2020 10:35 pm

Re: obd1 honda/gm daughterboard. 27sf512 EEPROM emulator

Post by b18libra »

texasgdp754 wrote:
Mon Feb 03, 2020 1:21 am
Revised the schematic where I had some errors. Re spun the PCB using more common sram chip. Will update thread once I've got some boards in hand and done some testing.

B18libra : if your capable of firmware development and willing to help I'd be happy to take the time to provide the info you asked for. Otherwise to be candid I won't spend the time to make the block diagram. Thanks in advance.
Doing further feasibility research on the topic I don't think there's anyway to be "clever" about the bus switching. You just need to switch the SRAM outputs faster than 100ns. 100ns - (10ns SRAM access) - (9ns 74HCT541 propagation) = 81ns to sense the ECU address change and switch the bus.

SRAM
70ns SRAM makes the problem near impossible, fit 10ns IS61WV1288EEBLL-10 SRAM it's £1.20

MCU
A single clock at 16MHz is 62ns. So it'll take 124ns just to read in the PIN register.
With a 64MHz you've got 5 clocks.
At 100MHz you've got 8 clocks.

To reach these clock speeds I'd recommend a something like a STM32.

It's crucial to do a feasibility study and understand the problem before jumping into detailed design.

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