Enable second UART in U-boot on Colibri-iMX6ULL

Technical Support
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1

I’m using U-Boot 2016.11-2.7.4+g1b121c6 on Colibri IMX6ull. I want to enable second uart to communicate with other board. Can any one give hint?

2

Which version of BSP Linux you are using (e.g. Linux 2.8b3?)

Just to be clear, do you have to send/receive data inside bootloader (U-Boot) (very early stage of boot), or in a Linux application?

3

Dear @rahul12789,

As @isaac states, could you please give us a little more detail about what you are trying to achieve? Do you need to that second UART in Uboot? What for?

4

@alvaro.tx @isaac I want to access second uart in uboot to communicate with other board via uart communication. I want to access second uart in Linux.

5

Dear @rahul12789, thanks for your answer.

You don’t need to do anything in Uboot to activate a second UART in Linux. In the iMX6ULL, by default in our most recent (2.8b3 and 2.7) Linux LXDE based image, 3 UARTs interfaces are available through /dev/ttymxc. Please check the following link.

Best regards,
Alvaro.

6

@alvaro.tx : I want to access it from uboot only not in Linux.

7

hi @rahul12789: did you try to use the second UART in uboot? Does it work?

8

I see from a previous question, that you already enabled the UART2 as debug output in Uboot. If what you are looking is how to send some UART frames while in Uboot, I don’t believe there is such a functionality rather than debug console or loading a binary with loadb. For more powerful functionality, I’m afraid you will have to wait until Linux loads. If you absolutely need that serial functionality as soon as possible, although it is not available in the iMX6 but in the iMX7, you could use FreeRTOS in the M4 core.