Welcome to a new Voltlog, in this video I’m gonna talk about the new CanLite revision D which is now ready to be ordered on my Tindie store and you’ll find a link to my Tindie store in the description below. Yes I am already at rev.D for these boards and that’s partly due to the ongoing global chip shortage which forces me to switch to a different switch with every new batch that I manufacture but I’ll get into that later, first if you don’t know what CanLite is let me tell you a few words about this board.
The idea for this board started back when I first experimented interfacing with the CANBUS for various automotive modules like the instrument cluster, the CAN gateway. The parking sensor module, the multimedia, I wanted to see what kind of messages get transmitted on the CAN bus network, if and how I can intercept and modify those or maybe insert my own messages so basically hacking on the CAN BUS network of my car.
I did a whole video on the subject a year ago voltlog #342 which I will link on screen if you haven’t seen that and you’re interested in the subject check it out.
So I wanted to create this little board that could be installed in a car and perform various functions on the CanBus, I chose the ESP32 as main processing unit because that’s plenty of processing power for the task on hand, it’s also cheap, it has wifi and built-in CAN peripherals so it was a logical choice for me to use it.
I still needed to add an external CAN transceiver to generate the differential voltage levels for the actual physical link and while I was there I also threw in an automotive grade buck regulator and a couple of automotive grade high-side switches just in case I needed to switch a load, something like a light or a motor, or whatever you might need cause these automotive high-side switches are pretty robust and you can drive pretty much anything you want with them.
And this brings me to the reason for revD, I’m sure you are aware of the ongoing global chip shortage and how car manufacturers have to stop their manufacturing plants because they can’t get the chips they need.. Well, guess where that left with my automotive high-side switches and automotive-buck regulator?
Yeah not a great choice of parts when it comes to availability, I mean, January 2023? That’s like 14 months away just for the buck regulator, all while people keep emailing me constantly to ask about the availability of the CanLite boards. The same thing could be said about the high-side switches I was using, they couldn’t be found anywhere and that’s not the only problem.
You can hardly find any alternative parts either, I’ve spent hours and hours trying to find replacements on Digikey and mouser and all I could find is low stock of parts that cost 10 times as much and come in much larger packages, but in the end my efforts paid off and I managed to find these, the BTS452T from infineon and although these have a lower maximum switch current, I had to settle for these, I mean 1.8A per channel is still plenty of current to be useful and we still get the nice features like over temp protection, over-current protection and general transient protection that these automotive switches feature.
I also had to go for a new inductor, which was slightly different, because that wasn’t available in stock either and don’t get me started on the lack of standardization when it comes to these surface mount inductor package, it’s like every time I need to use an inductor I also have to design a new footprint cause they are never the same exact size.