We could always talk BT since that still uses serial data on the device side
My Obdlink Mx runs just over 930K baud...

How about serial data over WIFI
I've used the Obdlink Sx over WiFi.....and the Obdlink Lx over USB
I've read and written a PCM with an Ardunio using USB, Serial FTDI converters and BT with out so much as a hiccup
Every BT Allpro that works with the Pcm Hammer was either built by me or likely had the instructions/parts list come from me


There is nothing wrong with using Serial data....but in the end USB is easy and works fine

 

Data point:

I've flashed my Subaru about 200 times, maybe 255. On two occasions I've had to repeat the flash due to the CRC verification step failing. On both occasions the second flash worked. It's never bricked itself. All using USB. For all I know, the failures might have been in the flash chip itself. There's no way to tell from the app.

That's with Tactrix EcuFlash, but PCM Hammer works similarly (probably all flashing apps do) and it has a similar verification step.

My only worry is collisions with other data on the VPW bus, but all the checks mentioned so far should make those a non issue anyway. So far, so good...

 

Hammer Report:

1st read: 1939 Chevy truck with 2002 truck ls
Full read with no problems.
2nd read: Stock 2000 GMC truck
Full read went ok but it left a Security problem behind. The engine would start but shut off immediately.
I had to do a power down reset to recover.
Also a save complete message would be nice when saving the bin file.
I know just enough about electronics to be really good at letting the magic smoke out.

Bill

 

Did you check for codes when the truck was shutting off right after starting? I'd love to know what the PCM thought was wrong at that point.

If I had to guess... maybe at anti-theft feature got triggered by the PCM being too busy with the read process.

I'm glad to hear it recovered though.

 

The dash message panel flashed SECURITY.
Maybe the body module was unhappy it was not invited to the party?
The '39 has all the security turned off.

 

Something like that, perhaps. It's just a guess though.

I get the security light during the flash, if I remember right, but after the flash is done it all goes back to normal.

It'll be interesting to see whether other people run into the same thing you did.

 

If I was to take a stab in the dark at this looking for a simple cause it was that the key was not turned off for at least 15 seconds after the Read/Flash was finished.

The BCM and theft should become inactive while the pcm is being read, once the flash is over they need to resync with the pcm. This would be like putting the wrong key in the ignition and turning the key on. As long as you didn't try to crank it with that key you would still be able to turn the ignition back off, put the correct key in and then start the vehicle. However if you cranked it with the wrong key it would trigger the Anti-theft.

In your case it's possible the security had just not re-synced with the PCM yet. Keep in mind if the vehicle has RAP(retained accessories power) you would need to open a door or wait for the RAP to time out for the BCM to actually shut down.

 

Sounds like we need a new message at the end of the flash, like "Remove your ignition key now, before the anti-theft gets suspicious."

 

Unrelated to the above: I just got a 1mb AMD chip to confess its identity, so we're a step closer to rewriting P59s.

 

OK, what did you use..... waterboarding, the rack, cat o' nine tails??

 

Which amply points out one of the major differences between hobby level work like we are doing here and professional grade like the big boys who will do a million or more testing cycles and log all the failures for cause and result before even selecting a connector type. If only we had the resources to duplicate their efforts. But that's not possible. So the next best thing is to look at what they are using and select, if not identical hardware, then at least hardware with the same characteristics.

I'm not going to harp on this. I don't want to distract you guys from carrying on with the good work. I'm only suggesting that as long as you're going to the trouble to do it, please don't make the same mistakes others have in assuming your hardware is good enough. You have to ask, as money conscious as some of the car companies have proven themselves to be, If you could save a penny why would you use a more expensive connector for instance? The answer is obvious, because it was required.

Any new ECM uses gas sealed connectors exclusively, and usually with dielectric grease. That's not to say a diagnostic port has to be held to the same high standards and they are not. But I think there's a fair argument that they are a more reliable connector than a USB port will ever be, and as virtually every other connector in a new car is now gas sealed and often greased, how long will it be before diagnostic ports follow suit? (Big rigs and buses have used them for decades.) Which is only a long way of saying that the USB port at the laptop is the weak link in the system.

Is there an alternative? Honestly you guys would know more about that than I do. Certainly it is easy and convenient and works most of the time. Probably you will never fry anything by using it and chances are very good you will never brickify anything either. Nothing but BT or WiFi even seems to have a ghost of a chance right now of being as good or better, and as some of you said, Serial, although reliable and good, has fallen out of favor. And since it's only the connection between the cable and the laptop we are talking about anyway it's only a concern if there's a sudden rash of failures. Let's hope not. (knock on wood) But if anybody could push for something better it'd probably be you guys. Me, I'm hoping for a good wireless solution eventually, but I don't think we're there yet.

Jim

 

Have you any idea Jim how many millions of vehicle ecu's get reflashed via USB cables around the world on a regular basis ? It's a mammoth industry across all types of vehicles.

Yes there are a few failures or bricks, but more often that's down to poor methods or someone doing something mid-flash rather than a problem with the comms method itself

In short...when flashing, once started touch absolutely nothing until it is finished.

 

We don't call it the PCM Hammer for nothing...

 

Yeah, you sure wouldn't want to take a chance of knocking the cable loose.

 

Nobody is making that assumption.

As Pete already told you, every message from the PC to the PCM contains two checksums. If those fail, the message is re-sent. And as I already told you, every reflash operation ends with a CRC check. If those fail (whether due to a transmission error that was hidden by a checksum false-positive, or due to a flash memory glitch, or just cosmic rays), the user gets a giant warning banner and the app tells them to flash again.

So its not really a question of whether or not the hardware can be trusted. It can't be trusted. That's why we already have three layers of error checking.

The question is really whether or not you trust a 32-bit CRC comparison.

If you have ever used a .zip file, you have trusted a 32-bit CRC to validate the integrity of your data.

 

And just to make sure this point is Hammered home() I've gone one step further and been directly addressing bricked PCM recovery for some time now. If just 1% of the BIN file is flashed to the PCM correctly I have found a way to recover the PCM with over the data bus even when it's been left in a non-responsive state.

The ONLY piece of hardware that should be questioned here is the 20 year old PCM your trying to flash that's been exposed to elements it's entire life. Electronic parts do degrade over time and honestly time is what's going to start killing these PCM's long before we run into noise issues from using USB.

 

You should go checkout my Android Elm flashing thread in this forum section. I'm way past the touching stage and have progressed into full blown flash molestation

 

It should also be noted that when this is finished we should be able to flash a bin onto any like PCM, correct? Theres so many of these PCMs in junkyards waiting to be snapped up for like $25 if you did have a mishap, then just flash your file on and go.

 

The 99-02 Pcm's are completely interchangeable as long as the server number ends in 896 or 0411.
03-07 will interchange for the most part, not all of them will work with drive by cable so you need to check that.

The FWD car stuff will not interchange even though they look the same, they are not compatible.

This isn't a 100% complete table but its got most of the server numbers and applications covered.It should have Trail blazers added for 2003/2004 that used the LM4 V8.

The 2003 12576106 is the only 1mb PCM that's going to be VERY picky about what file you flash it with. It uses a different flash chip then all the other 1mb pcm's, for what ever reason this pcm used an Intel flash chip while every other 1mb pcm used an AMD flash chip.

 

That table you just posted Pete is very helpful. Thank you.