Disabling Linux's Console UART ttys0

VIM3
1

Hei together,

is there a possibility to disable the Linux’s console UART ttys0,
like in Raspbian using “sudo raspi-config”
select option 5, Interfacing options , then option P6, Serial , and select No . Exit raspi-config.

We need this serial port for another use…!

Thanks for help
Regards from Norway

2

Hello kwklaus,

So you want to disable the debug uart? Waht you want to do with this uart?

Thanks.

3

IMG_0353
IMG_0353.JPG2448×3264 1.5 MB

Hei @numbqq nick,
In the attachment to this message, you can see our designed PCB.
Part of this PCB ist an 32Bit µController for different parts of working.
This PCB ist connected via an 40Pin Header, placed as SMD on the
down layer. To communicate from VIM3 Pro Board with the integrated PIC32MZ, placed on the PCB, need we the LINUX_TX/RX Channel.
All another connection at VIM3 GPIO Connector are occupied for differently Tasks, like SPI or I2C.
A bad possibility will it to be use UART_RX/TX_AO_B PIN 15/16,
because in future we need the SPI Channel.
Is there a possibility to use UART_RX/TX_AO_B PIN 15/16,
we trayed to use this, but it was not possible.

About the another topics with questions like SPI, Ubuntu Version and TS050, I will take contact with my software- team in Germany
and Estlan. I self are in Norway as project manager and electronic
developer.

Thanks for Help

1 Like
4

Hello @kwklaus

You can try to remove console=ttyS0,115200n8 in /boot/boot.ini file, then reboot the system.

There will be no kernel log output from the UART, and you can use it to communicate with the MCU.

Thanks.

1 Like
5

Hei numbqq Nick,

I tried to use your tip, I removed the lines console=ttyS0,115200n8 in /boot/boot.ini and reboot the system.
Result ist zero nothing happend, the debag port is always present. I testet it in parallel with an USB to serial adapter and Terraterm Terminal on an Windows PC and PIN18/19 VIM3 GPIO, the console/debagger is aktiv.
It’s possible to send over Linux_TX, I used a small C Testprogramm, but it’s not possible to read the Linux_RX
buffer.
Second question, how can I activate UARTC_RX/TX PIN15/16 on VIM3 GPI, may be it’s we will use it in future.
Thanks for help.!!!

6

Hei Nick,

wrote you my last questions about LINUX_TX/RX and UARTC_TX/RX ??

Regards from Norway
Klaus

7

Hello! I have same problem = we cannot activate PIN 15/16 UART.
And Khadas support not answering. Did you solve this problem?

8

Just a thought, but to activate SPI you have to modify dts and recompile kernel, maybe it’s the same with UART? I will follow this discussion and try to help since I will need to use SPI, I2C and UART aswell in just a few days.

9

Hi.

I have the same problem. I need SPI and UART for my PCB. Can I use RX/TX Linux pins for communicating with other peripherical?

Thanks for Help

10

Hello Jesus,

I would like to report you my experience.
Basicly it is possible to use the SPI port and the LINUX UART “ttyS0”.
But the experience with “ttyS0” was very negative, since Linux uses it mainly as a debug port.
I therefore use the port UART_C “ttyS3” PIN 15, PIN16 on the 40 pin. GPIO connector.
Both ports have to be in the .dts file changed, which ultimately means a lot of additional work.
see the code for changes:
I and my team have the Linux Ubuntu variant deferred for the time being,
since there are still important functions in Ubuntu absence.
For example, the HDMI port and a MIDI display like the TS050 cannot be operated in parallel.
For this reason, we are currently using Android 9 and are very happy with it.

Code:

iff --git a/arch/arm/boot/dts/amlogic/kvim3.dts b/arch/arm/boot/dts/amlogic/kvim3.dts
index daeff50…9e9eb7f 100644
— a/arch/arm/boot/dts/amlogic/kvim3.dts
+++ b/arch/arm/boot/dts/amlogic/kvim3.dts
@@ -1437,7 +1437,7 @@
};

&uart_C {

  •   status = "okay";

  •   status = "disabled";

};

&pcie_A {
@@ -1449,3 +1449,9 @@
status = “okay”;
};

+&spicc1 {

  •   status = "okay";

  •   pinctrl-names = "default";

  •   pinctrl-0 = <&spicc1_pins>;

  •   cs-gpios = <&gpio GPIOH_6 0>;

+};

11

Hello, kwlkaus

Thanks for your reply. I cannot use UARTC because I need to use the SPI port. So I think I will use USB_DP and USB_DM pins for serial communication.

Have you ever used this port? I suppose it will have to be activated in the .dts but I don’t know if it will give many problems (like Linux Rx / Tx).

Thanks for everything.

12

Hello Jesupi,
You can also use UART_A0_B on Pin 25 TX and Pin 26 RX.
It’s analog to carry out the transcoding from I2C to UART in the dts file.
I think UART_A0_B is not in ROM.
The distribution is
UART_AO_A = LINUX P18, P19
UART_A0_B = xxxxxx P25, P26
UART_A0_C = xxxxxx P15, P16
I had problems with LINUX port P15, P16 when booting,
here the µP board was addressed in an uncontrolled manner.
The VIM3 was also sporadically accessed even if ttyS0 was
declared as none console.
I have already used the USB port DM1 and DP1 in another project.
It behaves like a standard USB - OTG port.
We used it under Ubuntu and Androide.

regards from Norway Klaus

1 Like