Colibri iMX6ULL Serial Downloader over UART


I am struggling to get the built-in Serial Downloader to work over UART on the Colibri iMX6ULL (testing on the Iris board).

I can get the unit into recovery mode and have tested that the Serial Downloader works over USB (imx_usb and uuu are able to load u-boot into RAM) but when I try with imx_uart (or similar) there is no response on the UART from the iMX6ULL (using header X13 on the Iris which I believe is UART_A/1).

Our application may not have access to the USB lines in-field so it is important for us to be able to use the Serial Downloader over the UART.

Any help/suggestions with getting this working would be great.


Hi @madone

Could you provide the software version of your module?

What exactly are you trying to do? What is your application?

Best regards,

Hi Jaski,

I am using BSP 2.8.

What I am trying to do is test how to recover the device in the case that the NAND flash gets completely corrupted - to the point where u-boot won’t load. This also has a possible application in our production when we first load all the software onto the module.

What I am attempting to do is to get the Serial Downloader mentioned in section 8.9 of the iMX6ULL Reference Manual to work over the UART. According to the Reference Manual this is a supported mode.

Due to form factor and environmental constraints, our device won’t be able to have an external USB interface. So our concern is about trying to recover a device in-field if for some reason it is not able to load into u-boot. The only interface available to us is UART_A/1.

So far we have been unable to get any response from the Serial Downloader over the UART.

Kind regards

HI @madone

As you already stated according to the Reference Manual recovery mode over UART should work. We did not implement or tested this option for any iMX SoM, but for Colibri Vybrid, which is working fine.

You could check the implemented solution. The files are stored in the vf_flash folder of the regular Bsp image for Vybrid module. Let us know if you have any other questions.

Best regards,

Hello @madone ,

I am trying to do the same, but with a Viola Carrier board. I am facing the same issue. The Colibri IMX6ULL does not seem to respond to the imx_uart in recovery mode. I have tried entering the recovery mode by shorting the recovery pins on the module and also from u-boot(bmode usb) , there is no response in both the cases. Also tried the option of connecting the RTS and CTS appropriately, but does not seem to work.

Were you able to make any progress regarding the same ?

Hi @kavya,

Unfortunately I have not made any progress on this. It seems well documented in the iMX6ULL Reference Manual from NXP, so I would hope that it is possible and can work.

I’ll let you know of any progress I make.

Hello @madone ,

Thank you, that would be great.