Craig Moates

Folks,

I've been contemplating what I think is a pretty slick device. It would drop into your existing EPROM socket, ZIF, or whatever (instead of your 28-pin EPROM) and it would allow you to switch between multiple programs that have been loaded into a single Flash Prom.

Right now, what I have in mind would possibly allow 16 different programs for the 32K bins (730) and up to 32 (don't ask) for the 16K (165).

The selector switch would be right next to the EPROM. I'm thinking of providing for a 'remote' location for the switch, like by the gearshift or something via an extension cable. Rather than use dip switches or jumpers, I was just going to use a '****' that went from 1 to 16. Either that or a pushwheel/thumbwheel. Maybe a keypad? No.

I think it'll work, and I've got a layout designed for it, but there's a couple tricks that need to be pulled if it's going to work right, have to remap some pins. Any suggestions on this kind of device? What kind of characteristics are of interest?

Thanks for the feedback,
-Craig

Grumpy

Flip over to the syty area, and look around for the chips that they use like that. They had some teething problems about ribbon lenght, and RMI, RFI problems, yes even thou it was just a switch box. The wire lenght makes just such a nice antennae.

junkcltr

iTrader: (1)

Craig,
Don't let a little RF interference stop you. Just use a sheild around the ribbon/wire.
J

Jza

Maybe one of those little cobalt rings they used to stick on keyboards? dunno, just blowin smoke.

Jza

What exactly do those do anyway?

BTW, I'd be interested in that. Last year when someone was discussing something similar (but only with two or three different images) using DIP switches, I thought "What a great idea!".. It's sort of similar to JET's switchable PROM.. The one with the keyed switchbox and has stock, towing, valet, stageI, stageII, and all-out settings, or something like that. I thought their price was a little over the top, so a DIY solution to that would be very interesting to me.

89 Iroc Z

I would be very interested if you can switch on the fly. Would you be able to swich on the fly?

:hail: Craig Moates

AlexJH

Count me in, as long as it's not too expensive. The US -> CDN dollar exchange rate is brutal right now.

junkcltr

iTrader: (1)

Craig,
Don't try to rely on the mechanical switch to select the address line. You will get all sorts of problems(think or de-bouncing a switch). You need an electrical part to latch the mechanical to electrical signal. In doing this, it maybe possible to do switch reliably while the engine is running.
Jet products..........why doesn't anyone want to pay for good engineering anymore?
J

Craig Moates

Yep, the RFI could be a problem. Especially for on-the-fly switching. Gotta have an isolation circuit I suppose. I've got a touch of dream-world going here I think, so someone please ground me to reality at any point. Here's a cross-text from the Propane article:

"Yes, the RFI thing is bad news, but doable. I was thinking along similar lines. Placing an optoisolator (already have a quad-channel unit PCB layout designed) in the ECM box is a great way to go. Wonder if the ECM EPROM 5v supply can handle the transistor end of the optoisolator business? Might be a bad idea. Might want a separate ground too, really keep the isolation that way by going with separate supply. What do you think, use the existing EPROM supply? What about ground? This'll be important.

What I was thinking of is multi-part. Initially, I can set up a switching station via DIP switches external to the ECM for user control, and later I could add a transistor array to allow automated switching between programs via parallel port signals. For instance, one could load up a chip with a group of programs (say 8) and vary the programs to affect performance anticipation. Log the data from the car which characterizes performance under each program's control. When the needed data is collected (say, after a couple WOT passes or cruising), the program could be switched. By keeping track of the programs which are active, and given a little info about the program content, the 'mother' program could dictate the next set of program contents and thus strive toward 'auto-optimization'. It's a bit of a stretch, but it could be done with the right numerical methodology and data.

Anyways, in the absence of a real-time emulator, this might be an option that is very close at hand. "

junkcltr

iTrader: (1)

I haven't messed with looking at the RFI problem. But I wonder, how come my speaker wires work OK? When doesn't my analog MAF always give false readings? And so on. I have all of those wires right near the source of the problem (spark plugs)
Any thoughts?

J

89 Iroc Z

You could put the circuit in a metal enclosure, ground it, run shielded cable from the ECM to the circuit box, and ground the shield on both ends. Now I am not an expert or anything but that should stop any RFI problems. Your planning on putting the switching circuit right next to the ECM, with a external switch right?

Sarkee

Does JET produce good engineering products? (I don't know; never tried one...)

(Serious enquiry here; no sarcasm)

ws6transam

Craig,
Maybe what you need is an optoisolated interface and a PIC. That should make RFI a non-issue.

--Dan

89camaroRSV6

hey craig ... if ur idea is to take advantage of the remainng space on the 27C512/27C128 chip which has the same pin out as the 27C64/27C32 chip ( i hope the numbers are right)

yeah u are right ... u can have 16 - 32K bins in the 512K

but how are u gonna map the mem addressess... cos the ECM is always gonna look for the same addresses... (are u rearranging the pinss using the switches to get the same effect)

... ull have more serious problems with the mem adress mapping than with RF.. RF isolation is not that hard...

have u solved that yet...??

goog idea though craig...

Sarkee

Let me see if I grok this: Multiple BINs on one Flash EPROM???

Selectable by dip switches???...Set to access a specific memory location on the EPROM???

All mounted on a daughterboard like your adapters??? Using a 29C020 EPROM???

Feel free to jump in and correct any of these wrong guesses/interpretations of your email...

ws6transam

The ECM doesnt use all of the extra pins of the EPROM: It only uses a portion of the pins. The remainder of the pins are uncommitted. Thus, you can attach an external circuit to these pins and if you energise them, you can shift the addressing in the EPROM. Figure it this way: Lets say that you have a four-bit address space, but your ECM only uses three of these bits. The ECM can access addresses zero through seven. If you take the fourth bit true, a shift of EIGHT words occurs, and the ECM will now access word eight through fifteen. The ECM doesnt know any better: You have swapped to a different "page".

The same thing can happen in a 512K chip. The ECM accesses a 32Kbyte page. If you take unused address lines and energise them, you can swap to different pages of memory in the EPROM. THe ECM will then access the 32Kbytes but is none the wiser as to whether it is in page zero or page 15.

89camaroRSV6

ur right ws6, wat made me wonder was tat my idea was to use a Eprom emulator which im in the process of building ... and now im experiencing Bus contention problems ....im figuring a way to flash the rom even when it is in the ECm....

i was wondering if this would have the same problem ... as switching may not be fast enough ....

like for eg ECM is reading from location 0010 in ur 4 bit version

and all of a sudden u switch the mode to 1010 (the 1 is the control bit here) what happens ???

to our eyes the delay might not be seen but to the ECM this might be a slow process...(ie the switching might be slower than teh read)???

Sarkee

...You limp home...

junkcltr

iTrader: (1)

Craig,
It appears that there is a decent amount of interest here. Don't listen to the comments about switching always causing limp home. It doesn't have to be that way. Like I said before, don't rely on the mechanical swiching.......make sure it is done electrically. Sync with the chip select and it will work reliably. Remember where you heard this........BTW, I was bored waiting for a simulation of some stuff I am working on to finish last night so I checked out your ALDL source code. I don't know the BASIC language so it kind of looked strange to me. You got bugs in the version I saw..........bad checksum equations. Try FF. It works most of the time........just not all the time. Are you not releasing the source code for the other version??
Cheers,
J

Craig Moates

Yea, definitely I'll do it electronically. Hopefully just a mechanical switch coupled with an optoisolator array will take care of it.

I haven't put the new source code up lately, it's getting kind of kludgey to compile. Maybe with the next release (it's coming along, nice graphing stuff).

Probably right about the C/S eqn. Feel free to pass along a correction if you have a chance...

-Craig

ws6transam

Craig, Take the DIP switch and tie it to a set of S/R latches. Add a little red pushbutton next to the mechanical switches. Once you've dialed up your new page, press the button to "set". The button, of course, strobes the latches and they reset to the new value in sync. Run them to an optoisolator at the ECM, and hook up the collector of the opto to VCC and the emitter to the address line of the chip. Also tie a 10K resistor from the emittor to ground in order to pull down the address line when the optoisolator turns off.

junkcltr

iTrader: (1)

I am wrong about the checksum not working out. The first checksum doesn't work for 0xFF, but the equation always adds values that never sum up to 0xFF. So it is OK....my bad. The equations that really matter are correct. I should have been paying better attention.
J

Craig Moates

WS6:

Interesting route. I suppose the S/R latching array would prevent 'baubling' the optoisolators during switching? Is that the purpose, to allow the new bit pattern to be established and then instantaneously transmit it to the opto-array?

ws6transam

Yes, they will prevent problems with switch contact bounce, as well as prevent the ECM from jumping to pages that you really are not interested in using. Throw a 4-switch DIP in there, and you can access (via binary bit pattern) sixteen different pages. That ought to give us enough profiles for anything, wouldnt you think? One speed profile, one stock profile, and fourteen "Valet mode" profiles.

formula5

I have the emulator all mapped out.Kalmaker and others use ram and pc boards.It's too much hardware,too much overhead.I have'nt stated my total idea on thirdgen about an emulator.I don't want some bloke like kalmaker making cheddar off my idea.But it's real simple, software and a cable,thats it.Using a ribbon cable between the prom and ecm then connecting it to pp.Or better yet run without the prom,use the laptop.Instead of using a circut board and ram just use the laptop memory.Send a signal from the pp to the reset line in the ecm when the program updates.There is more details but you get the idea.For now I can change the chip at a stoplight so thats good enough for now