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posted in Hardware and Wiring read more

I'm using
as reference for the serial commands:
I want first to set the baud rate , so I tried:
0x01 0x08 0x0N Auto detect baud rate for bus N (Bus must be active for successful detection)

Then I tried :
0x03 0x01 0x01 NA Enable logging on bus 1 (do not touch current filter)

but got a single char and then nothing

Where did you take the 010102 ?

posted in Hardware and Wiring read more


Thanks for your reply,

First, as far as I know, the total resistance of the bus should be 60 ohms, thus we usually put 2 120ohms resistors on the ends , 2 parallel 120 ohms results total 60 ohm.
please refer to :
alt text

In the MCP2515 CAN bus monitor the 120 ohm resistor connectivity is determined by a FET transistor , which is controlled by the PIC18 MCU ,
So I decided to skip this part, and try to sniff the OBD2 port of my car.

I'm using Togglebit OBD2 cable from :

I connected the wire by colors :
CBT orange to wire green/black ,
CBT yellow to wire white/black ,
CBT green to wire blue/black,
CBT blue to wire yellow/black

I didnt connect the ground or power wires (Do I need to do that?)
I didnt add 120 ohms resistor, since I thought that its not needed when you connect CBT to a car bus.

The CBT couldn't detect any bus ( I used the serial API) I run the command :

I know that the serial commands work because I get info for 0101

Do you have any idea?


posted in Hardware and Wiring read more


Before using the CBT on my car, I wanted to check it with the demo board - MCP2515 CAN Bus Monitor Demo Board -

The MCP2515 CAN Bus Monitor Demo Board kit contains two identical boards which can be connected together to create a simple two node CAN bus.

On the network there is a D9 socket that can be used for sniffing.

I connected the CBT to the D9 connector (pin 2,7) for canH and canL
but didn't see any traffic.

Did anyone try it?