Can the CAN bus terminating resistor be “removed” from the Tracker One via some jumper pads?
Or the only way is to remove the terminating resistor? (Where is it located?)
I have an existing CAN bus network with 120 ohms resistor on each end and introducing the Tracker One will bring the line resistance to 40 ohms.
Thank you for requesting this. I also asked Particle for this as well.
My application is on Semi Trucks which already have 120 ohm resistors on the CAN line, and the manufacturer requests that all accessory devices do not have any CAN terminator.
It’s currently tricky to disable the CAN termination resistors from the Tracker One. They
are on the bottom side of the carrier board, between the underside of the B8B-PH connector that goes to the M8 and the SoM.
You need to remove both R1 and R10, each are 60.4 ohm 1206 SMD resistors, wired in series.
This is the view in Eagle CAD with the top layer hidden, so when you look at it from bottom, it will be reversed.
when the resistors are in series, why would one need to remove both?
wouldn’t cutting the trace in one place suffice?
having a cut/solder bride may be a good idea for future revisions.
There’s a capacitor connected in the middle of the series resistor pair, so only removing one will eliminate the terminating resistance but will leave the capacitor connected to the remaining side.
A way to make the termination resistance more configurable is being considered for a future revision.
Thank you for sharing the Eagle CAD view @rickkas7!
I believe the termination resistors have also been removed by default on newer Tracker One devices
Can you guys confirm this information? Is there a serial number after which the terminating resistors are gone?
FYI, I was told recently by one of Particle’s most excellent solution architects that the CAN bus resistors were removed by the time the “generally available” Tracker Ones were shipped. Pre-production samples might have the resistors in place. I noticed the datasheet has been updated, too (12/9).
I don’t have the specific serial number, but if it was ordered from the Particle retail or wholesale store after general availability (GA), the Tracker One does not have the terminating resistor.
Only the preview and beta test units had the 120 ohm CAN termination resistor populated.
