MCP2515 CAN BUS Board

[84S]

Hi,

I'd like to make use of a MCP2515 board in a project, and wondered if anyone can tell me if this is compatible with Feather boards? OR, if anyone can give me an idea of how I might find this kind of thing out myself by looking at the specs for the chips found on the board?

http://www.ebay.co.uk/itm/MCP2515-CAN-B ... SwmfhX65kl

http://ww1.microchip.com/downloads/en/D ... 21801e.pdf
http://www.nxp.com/documents/data_sheet/TJA1050.pdf

From what I can see from the datasheets above, the MCP2515 should work at 3.3v: "Low-power CMOS technology: - Operates from 2.7V – 5.5V"
I think the problem will be the TJA1050 which states the following in it's datasheet: "VCC supply voltage (min) 4.75 (max) 5.25 (unit) V"

I think I might have answered my own question?

Very green with electronics, so apologies if I've asked a very simple question. Don't shoot the software developer! :D

[adafruit_support_carter]

Looks like this board was designed to be used with 5V logic (like Arduino UNO). The current line up of Feathers have 3.3V. You might be able to use this board with a Feather if you incorporate a logic level converter:
https://www.adafruit.com/product/757

You could power the whole setup with 5V. The Feather will accept this as input and convert it internally to 3.3V.

[ERICBARIL72]

Hello Adafruit,

am just about to order 30pcs of this MCP2515 canbus PCB @ 3.3Volts
https://easyeda.com/armin.von_collrepp/ ... -0YRL3lfxP

Maybe adafruit would like to sell pre-assembled versions ?

[TinkerFun]

Nice Can Bus Board. How can I get one? Can I order the PCB? I need one for the next car project.

Best regards

[adafruit]

hiya!

please change the name (remove adafruit) thank you!

Adafruit CAN FeatherWing <-- not OK
CAN FeatherWing <-- that is OK

and please make it clear this is not made or designed or supported by adafruit so one is confused.

thank you!
adafruit support, phil

[ERICBARIL72]

Hello Adafruit, I did leave the creator a comment about updating the name but gotta say I simply showed you what I found when "googled" for better MCP2515 boards.
I have no relations with it.


Other then to say the Boards I received worked VERY WELL...
except maybe for mounting 0402 packagtes manually :-(

[SrMofo]

Hello Adafruit, I did leave the creator a comment about updating the name but gotta say I simply showed you what I found when "googled" for better MCP2515 boards.
I have no relations with it.


Other then to say the Boards I received worked VERY WELL...
except maybe for mounting 0402 packagtes manually :-(

ERICBARIL72, I came across the EasyEDA file as well which led me to this post ( as well as your dual CANBUS package). You say they work exceptionally well. Can you please explain in more detail what you needed to do to use these? Are they plug and play? Does code already using SPI need modified to adapt to the CANBUS protocol?

[ERICBARIL72]

The pcb footprint is designed to work with the feather footprint.
Out of the box, the MCP2515 library only needs the "CS" pin to be adapted based on the Shield
being used.
using the interrupt pin is optional but can make you software faster to treat incoming packets.

This board also lets you use the other I/O's of the mcp2515. I don't use them and have not mounted the resistors for those.


The trick is REALLY about those 0402 packages ! to avoid if you have never soldered before.
But EasyEDA is SO easy to use, re-laying a new Board can take an evening and you'd be able to use 0805.

Check the Xtal package. IT was as hard as the 0402's to solder. Not impossible but much easier using paste and reflow oven.

[SrMofo]

@ERICBARIL72, I had a few of these boards made and populated them this morning. Even after changing the CS and INT pins on my existing sketches (which work with the Seeed studio boards) the MCP will not initialize. Do you mind sharing your sketch and/or library that you are using? It would be helpful to easily eliminate the hardware as the issue.

[campr23]

Will adafruit be making and selling these? Should be pretty easy to do right?

[adafruit_support_mike]

No, we don't make them.. that's why we requested a slight change in the name above.

[ERICBARIL72]

@ SrMofo,

Debugging an MCP2515 design TIPS:
1- Blame the Xtal !
2- Blame yourself for not being able to prove it's the Crystal !

No , seriously, from my last 2++ years prototyping with various flavors of MCP2515 boards, here are my tips:
Step 1-
Power the MCP2515 board, NO CPU attached to it.
MCP2515 works @ 3.3 & 5V
Can transceivers are either 3.3V OR 5V ( check you've got the right one ).

- Check that you do have GND and Vcc at both chips
- Check that MCP2515 RST pin is pulled-up
- CS pin is pulled-up
- Check MCP2515pin 3 --> clkout
if no oscillations, blame yourself for:
poor solder joint ( only need 2 of the 4 )
Improver Xtal orientation ( I did fail on this one a few times )

Probing the Xtal pins with a scope doesn't work ! the impedance of the probe affects the oscillation circuit and stops the Xtal most of the times.

Step2-
SPI port and sketch stuff ! if your ever got one of those to work in the past ...
check that the Xtal frequency matches your .H file.
I have often found ebay 2515 can module @ 8 OR 16Mhz so you need to adjust the quantum values.
I have seen a .H file at one point where they have both flavors of #defines for 8 and 16

[SrMofo]

@ERICBARIL72

I should have updated this sooner. In my design I changed to another crystal available from digikey. I did eventually get the design running. Most of my main problem resulted from the library I was using. I switched to Cory J Fowlers library and all is well. Obviously I had to change the CS and interrupt to match, and then manually declare CS as output and interrupt as an input.
https://github.com/coryjfowler/MCP_CAN_lib

My next issue was intermittent and a bit harder to find. When I tried to probe the xtal I found it was not oscillating. Removing the series resistor from the design and increasing the parallel resistors value to 2M solved my issues. I too found that the XTAL oscillations would decay if I probed 1 side only.

I tried to find a decent tutorial or documentation from my old text books and the webs for properly selecting these values but came up dry other than rule of thumbs. Ultimately I just experimented with values until everything was working. For my first venture into schematic design and using XTALs I think I did ok

I had to assemble almost 40 of these so I ended up using a piece of aluminum on a hot plate to mount the majority of the SMDs and then a hot air gun to place the XTAL. I tried using the hot plate for the XTAL but had issues with it tombstoning on me almost every single time for some reason.