Hello,
I'm struggling with USB vcom example for quite a lot of time, it worked me when i used exactly the same chip as on FRDM-K22F board which is MK22FN512VLH12, but i decided to switch to little cheaper microcontroller to save some money but example is no longer working.
I did some changes in example to run on my custom boards(using internal clocks) and it works just fine on my custom board with MK22FN512 but when i load it to MK22FN128 it no longer works :smileysad:. Could u please point me in the right direction or tell me another solution how to add simple vcom to my application?
Also this driver takes 18Kb of RAM and MK22FN128 got 24kb but it's split into 16kb and 8kb so probably i need to change some things to make this work?
I setup memory as shown above but it ends up with an error:
Is it safe to reduce heapsize from 0x2000 to 0x1200 using this application or it will cause problems?
Oh and i forgot that i can't change clocks using clock tool in examples when changing mcu, because it wants to overwrite previous common drivers, after that operation example no longer compiles, any solution to that?
Thanks for any help :smileyhappy:
Hi
Unfortunately I don't think that you have the experience to be able to use the uTasker code in our project so you may need to debug and adapt the example that you have from the K22FN512. You already know that it doesn't run on the K22FN128 so you need to investigate why not and what needs to be changed.
Initially you need to start with an analysis of the clock configuration since it sounds as though the FRDM-K22F example is using the PLL, which doesn't exist in the K22FN128:
Top is from K22FN512 - bottom is from K22FN128 (note the absence of the PLL).
You can also try to configure the original FRDM-K22F project to use the IRC48M (crystal-less) because then the clocking would already be the same and then moving to the K22FN128 will be a smaller step.
In the uTasker project this is selected by a define:
#define USB_CRYSTAL_LESS // use 48MHz IRC as USB source (according to Freescale AN4905 - only possible in device mode) - this should always be used if not external !!
but it may be that the FRDM-K22F examples don't support this and so needs to be copied from other sources or developed form the ground up. There is a reference to crystal-less mode (and potential erratas that need to be worked around) at: http://www.utasker.com/kinetis/MCG.html
Beware also that the K22FN128 can only be used as USB device and can't be used a USB host unless a dedicated 48MHz oscillator input is supplied!
In fact the reference binary that I linked to is already using crystal-less mode on the FRDM-K22F and so would also run on your K22FN128. I can send you an operating project for your chip (and board) but it would need the ability on your behalf to add the library code to your project. A simpler technique is usually to take your existing application code and insert it into the uTasker framework since this avoids any complications, gives optimised drivers and the capability to simulate the complete operation which reduces development time and effort (and saves costs in professional work).
Regards
Mark
Thanks Mark,
Indeed it seems that the problem was with clock, i moved clock_config files and fsl_clock files from MK22FN128 project into USB example and it worked without problems.
There is only one last problem, example takes more than 16kb or ram, which actually will overflow SRAM_upper. Temporary solution was to change heapsize and change global data placement which allowed me to compile and flash. I'm not sure if it's good solution or it will have consequences eventually.
