bloodline

If I wanted to take an Arduino ARM (for some serious power), this is the board I would use the NETduino is not great for embedded development, I certainly wouldn't go near C# for this type of work. I already consider the C++ subset the arduino uses a little too high-level

My current ARM platform is the lovely mBED, but that is another project

bloodline

I've not used CPLDs, but I did think about using an FPGA... Bit really once you go down that route, the project needs more advanced soldering and multilayer technology.

Ideally the custom electronics should be no more than a simple board with a few discrete components that sit between the miata ECU plug (engine side) and the Arduino

bloodline

I totally agree than we need to move the project to GITHub, but as I'm currently Job Hunting I'm not able to spend any time on this project. Also I want to freeze the current code base, as I think I've come up with a much better way to implement it. My current timing model is a little too complex, and I think we could actually use a much simpler one freeing up a lot of CPU time

bloodline

I local garage had a '93 MX5 write-off in and I picked up the ECU for £20. My car is a '91 but I think the computers are compatible... This ECU is a B63H... I figured that even if the board was not compatible I would at least have an ECU Plug that I could use to make an Arduino->MX5 Loom adaptor.

But opening it up, it seems I lucked out! Someone has socket mounted the CPU (and mounted a Turbo daughterboard- Help identifying this would be good)... So If I could figure out the Pinout of the MX5's CPU I could interface the ECU with the Arduino much more simply and get some real world testing done.

I am aware that the CPU is some custom 6800 (Marked MP5270 in my attached photo)... but trying to find details of it is hard.

-Edit- All the chips on the daughter board have had their markings blacked out, I have tried to remove the ink, but to no avail :(
-Edit2- Googling around suggests the CPU might be a MC68HC908AP64... reading the datasheet now...

rb26dett

Screw this, mannnnnnnn, swap in a 4and1 disk instead of the DSM style disk and you can run FreeEMS RIGHT NOW :-) On a 4 cyl you can run wasted spark and sequential OR COP/CNP and semi sequential/bank injection. In a few weeks I'll have added the DSM/Miata decoder and you'll be able to run them like that without the disk swap. On any hardware you want. Without restriction. Free. Libre. Gratis.

Fred.

Reverant

iTrader: (10)

If they really wanted to run something off the shelf or somewhat ready, they would have installed a PNP Megasquirt or assembled a DIY V3 board and they would be golden by now. The point of this thread is that they want to do something completely on their own.

rb26dett

Urr, which drugs are you smoking dude? Next time I'm having a bad day I'd like to be that far away from the truth. There is nothing off-the-shelf about FreeEMS, what-so-ever, it's 100% DIY... to the core, to the grave.

Jeff_Ciesielski

iTrader: (10)

Do you have to write the code for it? Is it *THAT* DIY?

I'm not asking if you can, for free, unrestricted. I'm asking if you *have* to. As Reverant said, it wasn't about installing someone else's work on their cars. This is about building something completely from the ground up 100% on their own.

Now take your shitty attitude and go **** yourself with it.

rb26dett

You know, I was going to tear you a new arsehole, because you need it, BUT, then I saw your sig and decided you can't be that bad after all, do pull your head in, though, before it gets knocked off ;-)

Fred.

PS, you may have mistaken me for a noob, think again.

Jeff_Ciesielski

iTrader: (10)

E-thug is thuggish.

Well now, I'm sorry I injured your sensibilities. I know who you are. I've been following the DIYEFI thing passively for a while now because I'm interested in seeing where it goes and I may yet give it a run some day if and when megasquirt stops being interesting to me. Don't make the mistake of thinking that I'm insulting your abilities. You made a dick comment, you got a dick response.

rb26dett

No, not at all.

Thanks for that, I quoted you elsewhere, I hope you don't mind. I need to document the process that you're at the beginning of for the benefit of others. I find MegaSquirt* incredibly dull, because I understand it on every level. You'll have your epiphany eventually, don't worry :-)

No, not sensibilities, nor abilities, nothing injured or insulted.

Bingo, here is the part that IS confusing, I didn't! I'm not sure what you read or thought you understood. Whatever it is, though, it's irrelevant.

The only "mistake" I made here is believing that this behaviour from you both has anything to do with forum social pecking order, which can't be argued, because it is purely subjective.

Fred.

JustinHoMi

Oooh, that's interesting. I've never seen that daughtercard before. The only one I've seen before this one is the board from Grid in Japan (http://www.grid.co.jp/direct/direct150.htm).

The only other thing I can tell you about that ECU is that it's not a USDM one. There's no barometric sensor. I know the Japanese ECU's don't have barometric sensors, but I don't know about the European units.

kakarot

iTrader: (1)

AllData may have the stuff you looking for. Next time I get a chance to play with one (during this week) I will search for it.

bloodline

After reading the datasheet, it looks like the 68HC9 is a pretty standard 6800 in a 42pin package with a bunch of GPIO and 8 analogue inputs.

Now a question for the hardware guys, if I remove the CPU (and the daughterboard), then test the signal between a pin on the ECU plug and a pin on the CPU socket, will I be able to see what is connected to what... Given the very small amount of logic on the mainboard and the high IO count of the CPU, I am going to assume that for many pins there will be a 1:1 relationship between at least some of the signals on the CPU plug and the ECU plug... Can I assume this? Really, I would prefer if someone had a schematic for the ECU... Any joy?

FieldEffectDave

Its not really that easy to determine by simple probing: EG inputs might have common pullups, which means simple probing would find they are all sort of connected together. Output drivers are not going to have a testable connection between the uC pin and the connector pin.

The best way is to slowly work backwards from the ECU connector and reverse engineer the complete schematic.

I actually was planning to do this for the whole ECU anyway, mainly because I am interested in comparing the hardware input / output circuits and components we use in megasquirts to what was chosen for the OEM design. (And compare design margins etc...)

Should receive an ECU any day now hopefully and I will start, ill will take a photo of the PCB when I get it, I wonder how many variants of ECU there might be and how much they will differ internally?

JustinHoMi

I've spent a little while reverse engineering some of the circuits. You do have to be careful "copying" circuits from the OEM ECU to the megasquirt. You have to take the entire MS as a whole, and realize that there's more to it than just a bunch of individual circuits.

For instance, the OEM ECU uses a 10k resistor along with two caps to filter the AFM signal. The megasquirt suggested circuit for a MAF is a 2.2k resistor and two caps. If you compare the circuits you'll see that the OEM circuit has quite a bit more smoothing, which makes sense. However, if you look at the datasheet for the megasquirt's CPU, you'll see that they warn against using any resistor 10k or higher on the analog inputs, otherwise it could affect the timing of the readings.

bloodline

Yeah... I kinda figured as much...

I have no experience with hardware reverse engineering :(

You could well be the saviour of my project then As long as your ECU uses the same CPU, I'm gonna guess the IO is going to be the same (or similar enough for me to have a good starting point) as my ECU.

If I can help in any way then let me know.

If I can use my spare ECU as an interface between the Engine and the Arduino, I can do some real testing of my software

bloodline

I removed the Daughterboard to see what was underneath. Here is a photo of the main board, the socket is where the CPU goes... and where I want to attach a new Microcontroller, probably on a new daughterboard

FieldEffectDave

Havn't forgotten about this, just waiting for my OEM ECU to arrive!

bloodline

Cool! I'm busy with real life so no rush yet

I'm rather keen to rewrite my code using a simpler timing model!