topic Re: MKL27Z256 USB connection in Kinetis Microcontrollers

MKL27Z256 USB connection

joeygouly — Sun, 20 Sep 2015 23:19:50 GMT

Hi all,

I designed and made a PCB based on the MKL27Z256, unfortunately I'm having trouble with USB.

I think there might be something wrong with the USB connection, since when I plug it in it, the ROM bootloader should start, doesn't show up in dmesg as a USB device.

I have the ROM bootloader working with LPUART, but I want to get it working with USB to make sure that the USB connection is functional before trying to get my own USB stack working.

Note: I actually designed this for a MKL26Z256 part, but changed it at the last moment, but I think the USB parts are identical between the two.

Schematic:

PCB routing part:

I picked a "bad" usb connector that meant I had to swap the DM & DP pins with a via.. but since the traces are quite short I hoped it wouldn't be an issue. On the next revision, I'm definitely going to fix that.

I have tried testing the USB data lines with a multimeter and things seem ok. VBUS is also working, since I'm using it to power the board.

I'm just looking for some help on what might be wrong, and why the ROM bootloader wouldn't start over USB. I'm not actually sure *if* I should be seeing something in dmesg on Linux (I also have a Windows machine I can try, but not sure what I should see there either)

Any help appreciated!

Joey

ps. I have a couple of assembled boards, so might try the others, to see if this is just a bad one.

Re: MKL27Z256 USB connection

Kan_Li — Mon, 21 Sep 2015 07:51:33 GMT

Hi Joey Gouly,

The sch should be fine, but have you tried your board with a windows PC? If successfully enumerated , you may see it in the device manager. Please kindly let me know if the problem is still there.

Have a great day,
Kan

Freescale Technical Support
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Re: MKL27Z256 USB connection

joeygouly — Mon, 21 Sep 2015 12:08:43 GMT

Hi,

When plugged into a Windows machine it does not enumerate. I tried with a PCB I have flash with firmware, and a PCB that has a new chip on it.

I measured the D+/D- pins, and I have 3v and 0v respectively.

Is there some demo code I can flash with LPUART, and see if that works? i'm going to download the SDK now, and try find some.

Again, any help appreciated!

Thanks,

Joey

Re: MKL27Z256 USB connection

joeygouly — Mon, 21 Sep 2015 12:30:05 GMT

Another thing, is FSL_Kinetis_Bootloader_1_2_0.zip meant to contain the code that is in ROM of the MKL27Z?

I can see:

src/usb_stack/usb_core/device/sources/bsp/mk64f120m/usb_dev_bsp.c

116: USB0_CLK_RECOVER_IRC_EN = 0x03;

But this doesn't look like code that would be on the MKL27Z (mk64f120m, dunno what that is?)

If not, is the code in ROM available for download somewhere?

Thanks,

Joey

Re: MKL27Z256 USB connection

joeygouly — Mon, 21 Sep 2015 20:04:37 GMT

Turns out the USB cable was the issue.....