Flashhack - New LT1 flash tool

**steveo** · 04-15-2020

I suspect there might be some protection on the bus conflict on a hardware level, and the bombardment might just be ignored and never reach the pcm.

it works with fbody and bbody ecms, i think the window is just too tight for the entire message to land on a ybody where you have a window of less than 5 milliseconds to start sending the message.

I have seen logs on the factory tools and the bus is always quieted on the first try. I guess it is a pure ftdi latency that is crapping the code you have done. The only thing that help is direct usb connection without any virtual comm ports, but that only can bring more problems and compatibility issues. I guess a true comm cable will work much better for that manner.

yeah i agree ditching the virtual com port would be helpful as would implementing a serial api with zero buffering, in fact FTDI has that, however that'd require all my users to totally uninstall their FTDI drivers and install one that only works with my tool.

i have lots of experiments to run to solve this issue. i just wish i could spend time developing other parts of the program instead. i need this thing to connect to any aldl bus with even a shitty interface and i truly believe there is zero chance of doing that with timing

**kur4o** · 04-15-2020

Once I tried the gm factory tool and it didn`t want to connect with y-body bin. I did some sniff scan and the tool was trying to send mode 8 to ccm, but never get a response. I remember it sends once on a connect time and than 4-5 more times with some interval like a second. I think getting bus master is pretty straightforward, than it is simple mode 8 request. The timing is real tight here I did some calculations and with 8192 baud a byte is send for 0.9765ms. So any pause above 1.5 ms will indicate the bus is not active.

I think that strategy is used by the factory tool, wait for some predefined time of silence. Not sure if it can be done here with ftdi.

Another problem with y-body is that communications is between 2 devices so you have a request from ccm and a response from a pcm. While b-body is simple pcm dumping data.

Once the request is send the pcm will likely respond no matter if a mode 8 is send. Even the pcm is not a master it can recieve mode 8 too and respond to it. So trying to shut up ccm and pcm at the same time might give some positive results.

**steveo** · 04-15-2020

The timing is real tight here I did some calculations and with 8192 baud a byte is send for 0.9765ms.

yep i've pretty much called it 1ms for most purposes. so with an 8ms gap, you need to transmit in the first 4ms or it wont survive.

eehack does use a mode 8 request for bus keepalive or to check if the ecm is alive

this new tool is more procedural, it runs through an entire procedure without pausing, but before each packet it checks for up to 10ms to see if there's any crap in the buffer, and if there is, it tries to look for that bus master heartbeat packet thing again. so it's constantly checking to make sure it's still bus master

with an fbody, three requests 30ms apart always seem to land properly no matter when you start. garydoug that wrote scan9495 taught me that trick.

**steveo** · 04-16-2020

alright i have three methods i'm testing.

i'd love it if my two current test cases (nomakewan and sherlock) would test all three, i'll have them ready tonight in form of three buttons you can click, it'll tell us how long to connect, and how many attempts, then reset the bus master after, so you can try multiple attempts.

**Grizz1118** · 04-16-2020

My cable will be here today if you need me to try it I can as well

**NomakeWan** · 04-16-2020

Sounds good, can't wait!

I know you mentioned not wanting to do it, but I'd also be willing to test method four--the custom driver. I understand it's not practical for general use, but if that ends up being what it takes, I don't think it's unreasonable to note that Corvette guys would just need to go for a specific cable and use a specific driver. That is, if one of the three doesn't do the job.

**steveo** · 04-16-2020

nah i don't want you vette guys to run nonstandard drivers. i have written for libftdi before and it's great but you literally have to make your cable only work with libftdi. there's some hacky driver switching tool out there too.

if you haven't noticed, a lot of people tuning old gm stuff aren't too computer savvy, so i don't want to make my user base do things that'll just result in me having to teach them individually.

i think we'll find a method that'll work for everyone, although i'm thinking there's a chance you'll average around 10 seconds for initial connection time even with an ideal method.

just out of curiosity, what tools have you used that do connect reliably to your vehicles?...