General usage of the native USB on FRDM-KL26Z

[funkyguy4000]

Hello,

I've been looking through the KL26 family reference manual here: http://cache.freescale.com/files/microcontrollers/doc/ref_manual/KL26P121M48SF4RM.pdf?fasp=1&Parent_...
Long story short, I don't understand the USB implementation.  I've worked with many communication protocols although never usb directly.  I've used UART with a UART to USB bridge but that is as close to USB as i've gotten.eb

Can somebody explain the usage of the USB on the KL26Z? 
Bonus points if you can explain the technical stuff behind it, like in the reference manual, more simply as well!

-Shannon

[mjbcswitzerland · Accepted solution]

Shannon

I have written a document about USB (with some hardware details for the Coldfire which uses the same USB OTG controller as the Kinetis - valid for K and KL devices like the KL26Z) - http://www.utasker.com/docs/uTasker/USB_User_Guide.PDF

Unfortunately it is not simple to explain the operation and the user manual alone gives only a small part of the required details - the rest is study of the specification (best reading some decent books on USB because interpretaion of the specification is also only really possible by someone who who already understands the details anyway) and experimenting.

Maintenancy of the USB driver is not simple since it is heavily interrupt oriented and debugging a device is virtually impossible since a breakpoint during communication immediatly (within ms) causes a host connection to fail. I have therefore developed a Kinetis USB simulation which allow the code to be tested, studied and debugged - modeling the USB-OTG behaviour (use of buffers and interrupts). This is available in the uTasker Kinetis project.

Regards

Mark

[funkyguy4000]

Hey, that looks really great!
I wasn't aware that using native USB would be that difficult.  Thanks god I did use that as my final project for university.

Thanks you for the guidance!