FRAM NVRAM Board

EPROM EEPROM SRAM NVRAM Flash chips, reading/writing hardware and software
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FRAM NVRAM Board

Postby BennVenn » Fri Mar 04, 2016 11:31 am

Hi! First time poster, long time lurker.

With the flood of fake battery backed SRAM modules and the technology to finally bring FRAM IC's to the public at reasonable prices (US$3.10 EA) Is there any interest in an NVRAM board that will not loose its tune?

The FM18W08 FRAM IC operates from 3.3 - 5.5v, 70ns read time, 130ns write time and seems like an ideal solution. I don't think there is much demand for an '808 FRAM board these days but I thought I'd offer them here anyway. The delco is still far cheaper and just as capable as the latest generation of aftermarket ECU's, so why not use it!

I'll draw up the schematic tonight and route the boards, should have a batch of 10 on my desk in a couple of weeks for testing. Looking forward to getting a delco in my VW Bug!

Ben

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Re: FRAM NVRAM Board

Postby Holden202T » Fri Mar 04, 2016 12:27 pm

change it to a 512k or 1mb chip and it would probably be more appealing to people here.

i know i personally use a nvram with a 64kb tune on it, so that would be a minimum!

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Re: FRAM NVRAM Board

Postby BennVenn » Fri Mar 04, 2016 12:44 pm

Sorry if this is already documented elsewhere but what is the purpose of >64kb, other than having multiple tunes on the one chip? I didn't think the MCU could address more than 64k in the '808?

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Re: FRAM NVRAM Board

Postby Dylan » Fri Mar 04, 2016 1:20 pm

They are also used on a 424 ecu which runs our 11P code which is 64kb.

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Re: FRAM NVRAM Board

Postby BennVenn » Fri Mar 04, 2016 1:34 pm

Same memcal footprint?

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Re: FRAM NVRAM Board

Postby Holden202T » Fri Mar 04, 2016 1:39 pm

yep same memcal just larger size eprom.

largest of them is 512kb, and later model cars use a 1mb eprom, and they are different memcal all together.

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Re: FRAM NVRAM Board

Postby jenko » Fri Mar 04, 2016 2:31 pm

interested

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Re: FRAM NVRAM Board

Postby BennVenn » Fri Mar 04, 2016 3:17 pm

In that case, it might be best to make drop in eprom replacements rather than a memcal?

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Re: FRAM NVRAM Board

Postby antus » Fri Mar 04, 2016 3:55 pm

That does look pretty interesting. I would be interested to update our nvram boards to use those if they turn out to suit the electrical requirements of the delco cpu.

If they are reliable, and without a battery it'd make sense to build them straight on pcb and omit the socket.
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: FRAM NVRAM Board

Postby BennVenn » Fri Mar 04, 2016 6:13 pm

As for reliability, only time will tell. An ECU is exposed to less than ideal voltage and temperature conditions.

I've never designed a 'memcal' and from the data available it seems the 'netres' is important for limp mode when the Main MCU crashes/fails as well as cylinder selection. Is cylinder selection still via an analog voltage to the MCU or is it now entirely software defined in 12p?

Is the 'netres' included in the current NVRAM boards? Is there a pass-through to the original memcal and perhaps it uses that netres?

I have about 20yrs experience in microcontrollers, electrical and mechanical design and fabrication, embeded systems, ASM coding on almost every architecture and have designed and built a few custom ECU's - one is currently running in my bug. I understand the time and effort that has gone into the existing NVRAM revisions and don't want to step on any toes here. If any of the current distributors prefer I don't sell these I'm happy to honor that, or if they are looking for a very cheap reliable memcal, I'm happy to provide that too. What I would really appreciate is any pointers/gotcha's that will help me on my way.

From what I've read it looks like a standard EPROM tied to a MCU bus. I'll hook up the logic scope when my ECU arrives next week to check out the control lines and see if any additional logic is required to comply with the FRAM rise/fall times, pulsewidths etc... Also it would be handy to know if there is any logic required to gate the /WE signal to the FRAM. I'm not sure if 12p does a port write to toggle the line etc... for corruption protection.

I think that's all my questions. Oh would it be a good idea to throw in an FTDI bridge on there too? One board to rule them all!

And one last question - is there much info on the 12p binary? Known routines, code entry point/reset vector, port addresses for peripherals etc... It would be nice to have a tinker in there for things like anti-lag, active cylinder/valve cooling etc.

Thanks!

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