MK20 chip not recognised as serial port

[Epyon]

(This is a repost of this thread, because i realized it's more of a technical problem than a guidance question).

I've made a custom board with the MK20DX256VLH7 mcu together with the Mini54 TQFP chip from the PJRC store. However when plugging the USB in, the board isn't recognized by the PC and doesn't appear to boot. When pressing the program button, the board is recognized, but as a generic USB HID, not as a serial port.

Are the Mini54 chips from the PJRC store perhaps not yet compatible with the 256 chips (used in Teensy3.1)?

 

[stevech]

I do recall reading that the code in the Mini54 differs for Teensy 3.0 and 3.1.

 

[Epyon]

Yeah, but the Mini54 page on the PJRC shop says the chips are compatible with both 3.0 and 3.1. Could these be Mini54's with the old bootloader on them?

 

[PaulStoffregen]

When pressing the program button, the board is recognized, but as a generic USB HID, not as a serial port.

That's exactly how it's supposed to work. It's supposed to be a HID device with ID 16C0:0478

http://www.pjrc.com/teensy/check_halfkay_xp.html

If you're used to regular Arduino, where everything appears as a serial port, perhaps this page will help. Scroll down to "No Serial Port While Programming"

http://www.pjrc.com/teensy/troubleshoot.html

Are the Mini54 chips from the PJRC store perhaps not yet compatible with the 256 chips (used in Teensy3.1)?

The switch was made on the Mini54 chip in late 2013 (a couple months before the 3.1 release). Only very old chips would be 3.0 only.

 

[Epyon]

Thanks for the clarification Paul. After loading a serial sketch, the chip shows up as a serial port.