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Forum Index : Microcontroller and PC projects : Anyone done CAN Bus communications
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Hans Senior Member  Joined: 18/10/2022 Location: CanadaPosts: 116 |
Hi All; I tried to search for "can bus" in the forum but there are too hits on bus or can as in can't etc. So I am asking if anyone has done any communications over can bus to talk to devices that use this protocol? I need to understand how I can hook up a pico to experiment with talking to an automotive device. This will be more of a hacking experiment in the end I suppose.  Any programming supplied would be much appreciated. Thanks guys! Hans ...  |
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phil99 Guru  Joined: 11/02/2018 Location: AustraliaPosts: 2135 |
If you copy:- Site:thebackshed.com "can bus" into your browser search bar there are a few threads that come up but appear to be for Arduino not MMBasic. CSub LOG (last compiled for MMBasic v5.08.00 by @Disco4Now) can capture fast data streams in an array for later processing. Another option is to use the ADC command to capture a stream of samples that can later be converted to data. Edited 2024-08-25 12:14 by phil99 |
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disco4now Guru Joined: 18/12/2014 Location: AustraliaPosts: 896 |
I have been playing around with the MCP2515 CAN module and have a driver for it for MMBasic. It probably needs a bit more documentation on where to adjust for your environment but essentially needs the SPIOPEN and SPICLOSE routines adjusted for a Pico and set the appropriate CS pin. See this item on fruitoftheshed where I have started to document it. The Armmite F407 and Armmite H743 chips have a native CAN controller, the next release of MMBasic will expose these to MMBasic (i.e an MMBasic CAN command) so you will only need a transceiver chip such as the SN65HVD230 CAN Transceiver. SN65HVD230 CAN Transceiver I have these working, just need to tidy up the documentation. Gerry Latest F4 Latest H7 |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6779 |
There used to be an official version of MMBasic that supported CAN bus. Wasn't it for the original Colour Maximite? You plugged the hardware for it onto Arduino-arranged sockets on the board. I think it was one of those things that got dropped as it took a lot of resources and was of limited interest. Geoff probably still has the info on it. There may be something on his site. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3194 |
Many moons ago (in 2012) John Harding added support for the CAN protocol into MMBasic for the original Colour Maximite. It was dependent on the CAN module integrated in the Microchip PIC32MX795F512L processor and I released it as a separate version to the standard version of MMBasic. I know very little about the CAN protocol so I never tested it but quite a few people did use it and apparently it did a great job. You can still download the firmware+documentation package which is buried in my website at https://geoffg.net/OriginalColourMaximite.html (scroll down to the downloads section at the bottom). Unfortunately, because it is dependent on the PIC32MX795F512L chip it will not work on the PicoMite. Geoff Geoff Graham - http://geoffg.net |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 857 |
This is just never-ending awesomeness   |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6779 |
Thanks Geoff. My memory wasn't a complete disaster then. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| oh3gdo Regular Member  Joined: 18/11/2021 Location: FinlandPosts: 47 |
Hans I did a Can device for car last January It is here: http://probyte.fi/Can7.jpg It uses a PIC 18F26K80 compiler and it must work in the car. I used CCS v5.115 c-compiler. I reads with uart a data from other measuring device, but the customer needs that its customer knows that they have done it and they have used CAN before. The customer can't say what CAN address I can use. Anyway, it was a quite job to do the software. There were too different similar messages, which must to turn CAN data, but they must first separate. The CAN data is very small and my input data was 32 bits long. I needed a CAN measuring device, but first Swedish can device doesn't worked. The second device worked. Anyway after 1.5 months works it succeed, but the customer didn't get it work and send it back. We checked it and it worked well and send them to Paris. Then the customer got it working. The software is a my customer, so I can give it, but I can do a new one. Pekka Ritamaki oh3gdo@gmail.com |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 857 |
Hey Gerry, are we talking CAN FD or Classical? Exciting stuff |
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| disco4now Guru Joined: 18/12/2014 Location: AustraliaPosts: 896 |
The H743 does support CAN FD but I have only developed the MMBasic syntax to set it up for Classic mode for now. Latest F4 Latest H7 |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 857 |
Just been reading about it Downloaded "CAN Bus The Ultimate Guide", too big to upload here. Claims of near-zero latency. I really need to investigate. |
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| Hans Senior Member Joined: 18/10/2022 Location: CanadaPosts: 116 |
WOW! Thanks guys so many things to check out almost don’t know where to begin. This is what I love about this forum, there are so many guys with so many different interests when you ask a question you’re bound to run across multiple people that have multiple answers to give you direction. Thanks so much guys. I gotta look at all of these posts and see what I want to pursue, I’ll definitely be back with some questions . Thanks loads. Hans … |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3800 |
With motors it may be "near-zero" but it's a bus so a node wishing to send has to either abort current traffic or wait and unless it's the highest priority node may have to keep waiting. Is it only non-techs who make claims like near-zero for comms latency?! John |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 857 |
True. I use a 4-wire RS485 but I don't rely on it for coordinating motion. |
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| Hans Senior Member Joined: 18/10/2022 Location: CanadaPosts: 116 |
Thanks Gerry. I have a couple of those modules on order, should receive them tomorrow. How do you identify the high and low line of the bus? Is it try one way and if no coms then the other? Thanks a bunch, Hans ... |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 857 |
I believe that it's a standard RS485 signal. For each valid high, there's a mirror-image low. A noise spike would be uni-directional and would be rejected. |
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