MCP_CAN Library
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#14 Compare This branch is 41 commits ahead, 6 commits behind reeedstudio:master.
Latest commit 0fb5064 Jan 12, 2018
coryjfowler committed Jan 12, 2018 Mask & Filter Bug
Was not setting extended ID flag correctly due to looking at the wrong argument...

Sub-Development branch was copied to Master on June 30th, 2016.

MCP_CAN Library for Arduino

MCP_CAN library v1.5 This library is compatible with any shield or board that uses the MCP2515 or MCP25625 CAN protocol controller.

This version supports setting the ID filter mode of the protocol controller, the BAUD rate with clock speed with the begin() function. Baudrates 5k, 10k, 20k, 50k, 100k, 125k, 250k, 500k, & 1000k using 16MHz clock on the MCP2515 are confirmed to work using a Peak-System PCAN-USB dongle as a reference. Baudrates for 8MHz and 20MHz crystals are yet to be confirmed but were calculated appropiately.

The readMsgBuf() functions bring in the message ID. The getCanId() function is obsolete and no longer exists, don't use it.

The readMsgBuf(*ID, *DLC, *DATA) function will return the ID type (extended or standard) and it will bring back the remote request status bit.
If the ID AND 0x80000000 EQUALS 0x80000000, the ID is of the Extended type, otherwise it is standard.
If the ID AND 0x40000000 EQUALS 0x40000000, the message is a remote request.

The readMsgBuf(*ID, *EXT, *DLC, *DATA) function will return the ID unaltered and doesn't inform us of a remote request.
If EXT is true, the ID is extended.

The sendMsgBuf(ID, DLC, DATA) function can send extended or standard IDs.
To mark an ID as extended, OR the ID with 0x80000000.
To send a remote request, OR the ID with 0x40000000.

The sendMsgBuf(ID, EXT, DLC, DATA) has not changed other than fixing return values.

Using the setMode() function the sketch can now put the protocol controller into sleep, loop-back, or listen-only modes as well as normal operation. Right now the code defaults to loop-back mode after the begin() function runs. I have found this to increase the stability of filtering when the controller is initialized while connected to an active bus.

User can enable and disable (default) One-Shot transmission mode from the sketch using enOneShotTX() or disOneShotTX() respectively.


Copy this into the "[.../MySketches/]libraries/" folder and restart the Arduino editor.

NOTE: If an older version of the library exists (e.g. CAN_BUS_Shield) be sure to remove it from the libraries folder or replace the files with those in this library to avoid conflicts.

Help and Support

This is primarily for non-bug related issues: Please start a new thread in an appropriate area at Seeedstudio forums or forums and then send me (coryjfowler) a link through the PM system, my user name is the same as it is here. I will receive an email about the PM and generally get to it with-in a week or less. Keep in mind, I do this in my spare time.

Happy Coding!