Mini UART on RaspberryPi CM3/CM3+

[Ahmad Fatoum]

Hello Robert,

On 10/5/20 12:07 PM, Robert Carnecky (Neopsis) wrote:
> Did anybody successfully configured Raspberry CM3/CM3+ mini-UART as
> the Barebox console? I found a thread
> on this list discussing the issue
> (https://www.mail-archive.com/barebox@lists.infradead.org/msg35235.html),
> unfortunately without any solution.
> 
> What I need:
> 
>    * UART0 on pins 32/33 (technology access over rs-485)
>    * UART1 (miniUART) on pins 14/15 (console)
> 
> My current config.txt boots fine my raspberry kernel (zImage built
> using builroot):
> 
>    kernel=zImage
>    enable_uart=1
>    dtoverlay=uart0,txd0_pin=32,rxd0_pin=33,pin_func=7
>    dtoverlay=uart1,txd1_pin=14,rxd1_pin=15
> 
> Now I would like to switch to Barebox as a bootloader. I compiled the
> barebox image with
> 
>    * CONSOLE_ACTIVATE_NONE = Y
>    * 'stdout-path=&uart1;' in  'arch/arm/dts/bcm2837-rpi-cm3.dts' .

I don't have a CM3, but are you sure uart1 is enabled?

Try adding to arch/arm/dts/bcm2837-rpi-cm3.dts:

&uart1 {
        pinctrl-names = "default";
        pinctrl-0 = <&uart1_gpio14>;
        status = "okay";
};

If that doesn't help, use CONSOLE_ACTIVATE_ALL and listen
on UART0 before the RS-485 transceiver and paste the
dmesg and devinfo input you get.

Cheers,
Ahmad


> 
> and changed my kernel in config.txt
> 
>     kernel=barebox.img
> 
> I cannot see any output on pins 14/15 e.g. UART1, no barebox console,
> no kernel console.
> Any idea what's wrong here?
> 
> Robert
> 
> _______________________________________________
> barebox mailing list
> barebox at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/barebox
> 

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