Cortex M4 and MFRC 522 library ?

Trying to compile a simple sketch with reference to SPI.h and mfrc522.h. It will not compile for the Adafruit Cotex M4 Express boards which are supposed to be Arduino compatible; such as Itsy Bitsy M4 Express or Metro M4 Express. I'm told this is possibly because " the library uses some values (like SPI_CLOCK_DIV4) that aren't defined for M4."

Is this correct and is there something that can be done to correct it if this is true? Here's my sketch:


When you encounter an error you'll see a button on the right side of the orange bar "Copy error messages" (or the icon that looks like two pieces of paper in the Arduino Web Editor). Click that button. Paste the error in a message here USING CODE TAGS (</> button on the forum toolbar). If the text exceeds the forum's 9000 character limit, save it to a text file and post it as an attachment. If you click the "Reply" button here, you will see an "Attachments and other settings" link.

If possible, you should always post code directly in the forum thread as text using code tags (</> button on the toolbar). This will make it easy for anyone to look at it, which will increase the likelihood of you getting help. If the sketch is longer than the forum will allow then it's OK to add it as an attachment. After clicking the "Reply" button, you will see an "Attachments and other settings" link.

Please don't put your code in some external file service like dropbox, etc. We shouldn't need to go to an external website just to help you. Some forum members won't do that, resulting in you having a lower chance of getting help. External resources tend to disappear over time, causing the forum thread to be a much less useful resource for others who have the same problem.


You're welcome, but just saying "thx" isn't going to do much to get your problem resolved. I told you what you need to do if you want help. The ball is in your court.