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ESP32 Dev board and CAN 2.0 - Very confused
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ESP32 Dev board and CAN 2.0 - Very confused

by jarcher on Mon Feb 25, 2019 3:34 am

I have reviewed the ESP32-VROOM-32 data sheet and the ESP32 technical documentation. In the peripherals list a CAN 2.0 channel is listed. But when I check the pinout diagram I can find no mention of it. I have seem modules that use it, so I suspect it's really there.

But where? Which pins does it use?

Also, do I assume that the module ha a CAN controller but not necessarily a transceiver, but again, I can't find that info in the datasheet.

So, I guess my question is, what support circuitry do I need to use the ESP32 CAN bus and where do I connect it?

Thanks very much...

jarcher
 
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Re: ESP32 Dev board and CAN 2.0 - Very confused

by adafruit_support_mike on Tue Feb 26, 2019 2:22 am

The ESP32 uses a general-multiplexer strategy: there are 162 inputs and 176 output signals that can be mapped to the physical pins. Any of those signals can be mapped to any physical pin through the GPIO multiplexer. There's also a secondary IO_MUX for high-speed signals that map to specific groups of pins. In general, you choose the features you want, to use, decide which pins to use, then configure the multiplexer appropriately.

I just looked through a copy of the ESP32 datasheet version 1.8 and didn't see a CAN peripheral though. What version of the datasheet do you have, and what section or page mentions CAN?

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Re: ESP32 Dev board and CAN 2.0 - Very confused

by jarcher on Wed Feb 27, 2019 12:55 am

Thanks Mike, please see:

https://www.espressif.com/sites/default ... eet_en.pdf

On page 3, section 1.4.3, Advanced Peripheral Interfaces. This is datasheet version 2.8 from 2019.

Also, I have read that other people are using the ESP32 for CAN Bus, but what's not clear is if I need an external CAN transceiver (such that only the controller is in the ESP32 SoC) or if the actual transceiver is in there.

Thanks again...

jarcher
 
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Joined: Sun Mar 27, 2011 2:49 am

Re: ESP32 Dev board and CAN 2.0 - Very confused

by adafruit_support_mike on Wed Feb 27, 2019 2:31 am

Thank you, I had an older version. Apparently the CAN controller was released in late 2016.

From what I can tell based on further reading, the ESP32 only has a protocol controller, and you'll need an external transciever to communiate with the physical CAN bus.

It looks like this is the software support library:

https://github.com/ThomasBarth/ESP32-CAN-Driver

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Re: ESP32 Dev board and CAN 2.0 - Very confused

by jarcher on Wed Feb 27, 2019 8:08 pm

Thanks Mike, that's what I thought. So my last question is, does the ESP32 Feather board break out all the pins of the ESP32, or just some of them?

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Re: ESP32 Dev board and CAN 2.0 - Very confused

by adafruit_support_mike on Thu Feb 28, 2019 1:39 am

Only some of them. The ESP32 has 34 physical pins and the Feather pinout uses 20.

Espressif's dev board breaks all 32 pins out to the sides of the board:

https://www.adafruit.com/product/3269

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Re: ESP32 Dev board and CAN 2.0 - Very confused

by jarcher on Thu Feb 28, 2019 2:34 am

Thanks again.

jarcher
 
Posts: 50
Joined: Sun Mar 27, 2011 2:49 am

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