Vida CEM swapping

blasaab · Post by **blasaab** » 26 Mar 2021, 05:18

Hi again
the max3051 is not available from my dealer see picture is this transciver the same?
and on resistor there is many options on is it a standard 0,6w?

Post by **RickHaleParker** » 26 Mar 2021, 09:25

solitaire wrote: 25 Mar 2021, 05:25 but then need modify schematic for logical voltage level...

Getting there. Need to wait for the coders to decide on K-Line RX & TX pin assignment.

: Schematic_CEM cracker_2021-03-26.png (77.63 KiB) Viewed 1315 times

Post by **vtl** » 26 Mar 2021, 09:34

Rick, you also need a wire from CAN-HS RX to Teensy pin 2. This is how the code looks at the signal and identifies latency jitter.

Post by **RickHaleParker** » 26 Mar 2021, 10:27

vtl wrote: 26 Mar 2021, 09:34Rick, you also need a wire from CAN-HS RX to Teensy pin 2. This is how the code looks at the signal and identifies latency jitter.

You mean run a jumper from Teensy pin #2 to Teensy pin #23 (CRX1) ?

: Schematic_CEM cracker_2021-03-26_X.png (78.89 KiB) Viewed 1298 times

MaxDenisov · Post by **MaxDenisov** » 26 Mar 2021, 14:47

MaxDenisov wrote: 10 Mar 2021, 05:20 Pin for my XC90 added to Vdash:

Today i tried to make changes to configuration of my car using Vdash and PIN( Thanks to Vtl)

Thanks to Vdash team for great support!

PIN is working well for configuration change:

Freedom!

Post by **RickHaleParker** » 26 Mar 2021, 15:02

blasaab wrote: 26 Mar 2021, 05:18 on resistor there is many options on is it a standard 0,6w?

It need to be 120Ω. It is a CAN Bus terminating resistor. Specs are 120Ω at each end of the CAN Bus. The other 120Ω is in the CEM.
Power in watts = V²/R = 5V²/120Ω = 25V/120Ω = 0.21 V/Ω = 0.21 Watts. Needs to be 1/4 Watt or higher.

blasaab · Post by **blasaab** » 26 Mar 2021, 15:24

Thanks i have order both 0.6 and 1watt then it should work

3r1k · Post by **3r1k** » 26 Mar 2021, 18:09

A while since I posted in this thread, but I have been following along. What are folks planning to use the pin for?

The reason why I am asking is because I don't see any use except using Vdash or similar to change the CarConfig? Or is there another usage where you want to change the CEM flash memory?

Myself have been trying to understand how to do the CarConfig change myself (over canbus), but atm I am struggling with writing a SBL to make any adjustments to the flash memory (where carconfig is stored). I have no problems changing the CarConfig by soldering into the MCU and changing the different parameters manually, but it is a tedious and slow process.

I think it would be a great thing for the Volvo community if we could find an easy way for people to make changes to the CarConfig by using the cracking method vtl has developed?

Quattrodag · Post by **Quattrodag** » 27 Mar 2021, 11:11

RickHaleParker wrote: 26 Mar 2021, 09:25
solitaire wrote: 25 Mar 2021, 05:25 but then need modify schematic for logical voltage level...
Getting there. Need to wait for the coders to decide on K-Line RX & TX pin assignment.

Schematic_CEM cracker_2021-03-26.png

and what program to install on the computer to read the pin

Post by **RickHaleParker** » 27 Mar 2021, 11:27

Quattrodag wrote: 27 Mar 2021, 11:11 and what program to install on the computer to read the pin

https://github.com/vtl/volvo-cem-cracker
Keep in mind this is a work in progress not a finished product. Not all information sources are up to date. Best to go back to the first page of this thread and get up to date as much as you can.