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FRDM-K64F J6 header pin reassignment?

Question asked by Rob Bossemeyer on Feb 19, 2015
Latest reply on Feb 19, 2015 by Mark Butcher

I'm teaching an embedded systems course at Grand Valley State University and I had my students purchase a FRDM-K64F board for prototyping projects in lab (we use KDS as our IDE).

 

I purchased two FRDM-K64F boards this past summer to try out some project ideas.  One of our projects involves connecting to the J6 header a nRF24L01+ daughter board to communicate over a wireless link between boards.  I was able to test this project successfully on my boards.  When my students came to lab on Monday to work on this project, none of them could get the radios to transmit or receive.  I worked with a student group on troubleshooting their implementation using a logic analyzer  and this led us to the discovery that the CE line to the daughter board was not responding as programmed.  So we identified the problem, but, were perplexed about it.

 

What made things even more interesting was that when the student project was downloaded onto my FRDM-K64F boards, the radios worked fine and we were able to transmit data and receive acknowledgement on one board and receive the data packet on the other board.  Finally, one of the student groups decided to trace the connection on the J6 header pin 3 that is used for CE and that is (according to the photo that accompanies their boards) supposed to be connected to PTC12 on the MCU and found that it was connected instead to PTB20!  When students reprogrammed CE to be controlled by PTB20, their projects now worked on their boards.

 

I discovered that my boards have a Rev B sticker on them while the student boards have Rev C on theirs.  My question is why this change was not documented in the schematic or the photo on the card that came with the student boards?  I've searched for a description of this change (or error) on your website and have not found any mention of it.  I'm surprised if no one else has reported this change, but, just in case this is new information it should be posted so that others are aware.

 

Sincerely,

 

Rob Bossemeyer

Assistant Professor

Padnos College of Engineering & Computing

Grand Valley State University

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