Disable UART0 from Debug

Hello Sir,

                    It is  of android .

Hello Sir,

                  I want to convert the PR1_UART0 into UART0 ,  i need the procedure to that conversion. And moreover i want to use the UART0 rather than the debugging purpose. 

Is there any way to stop the UART0 from debugging so that i can connect another device.

Hi,

To change the serial console for the SPL/U-Boot, recompile the SPL/U-Boot with the following target: am335x_evm_uartX, where X is a number from 1 to 5. For example:

make am335x_evm_uart1

To change the serial console for the linux kernel, you need to change the "console" boot argument from inside U-Boot. Do the following inside U-Boot before starting the kernel:

setenv console ttyO1, 115200n8

To change the console inside the root file system (user space), you need to change the inittab file inside the rootfs partition. You can do that by mounting the rootfs partition on a Linux host and modifying the file there. Please note that this applies for the Linux rootfs and the Android rootfs differs from it, so I'm not 100% sure if this is the correct way to do it for user space.

Best regards,
Miroslav

Hello Sir,

                 Thanks for your reply,instead of changing  UART0 to another UART(1-5). Is there any way to stop the UART0 from debugging.

Hi,

Please read the U-Boot documentation file "README.silent" located in <u-boot_folder>/doc/README.silent:

The config option CONFIG_SILENT_CONSOLE can be used to quiet messages
on the console.  If the option has been enabled, the output can be
silenced by setting the environment variable "silent".

- CONFIG_SILENT_CONSOLE_UPDATE_ON_SET
    When the "silent" variable is changed with env set, the change
    will take effect immediately.

- CONFIG_SILENT_CONSOLE_UPDATE_ON_RELOC
    Some environments are not available until relocation (e.g. NAND)
    so this will make the value in the flash env take effect at
    relocation.

The following actions are taken if "silent" is set at boot time:

 - Until the console devices have been initialized, output has to be
   suppressed by testing for the flag "GD_FLG_SILENT" in "gd->flags".

 - When the console devices have been initialized, "stdout" and
   "stderr" are set to "nulldev", so subsequent messages are
   suppressed automatically. Make sure to enable "nulldev" by
   #defining CONFIG_SYS_DEVICE_NULLDEV in your board config file.

 - When booting a linux kernel, the "bootargs" are fixed up so that
   the argument "console=" will be in the command line, no matter how
   it was set in "bootargs" before.

Best regards,
Miroslav

Hello Sir,

                could u explain how i need to set the silent booting process in order to use UART0 for connecting device.

Hi,

There is an am335x specific board config file located in <u-boot_folder>/include/configs/am335x_evm.h. You need to #define CONFIG_SILENT_CONSOLE there. Please note the following:

 - When the console devices have been initialized, "stdout" and
   "stderr" are set to "nulldev", so subsequent messages are
   suppressed automatically. Make sure to enable "nulldev" by
   #defining CONFIG_SYS_DEVICE_NULLDEV in your board config file.

This means you will probably need to #define CONFIG_SYS_DEVICE_NULLDEV as well.

Best regards,
Miroslav

Hello Sir,

               I tried out what you said but It is not working out properly. Could you suggest any reason for it.

Hi,

Inside that same board config file, under the CONFIG_EXTRA_ENV_SETTINGS, add the following lines:

#ifdef CONFIG_SILENT_CONSOLE
    "silent=1\0" \
#endif

Best regards,
Miroslav

Hi again,

Actually I seem to have missed to point out something. I checked the sources (<u-boot_folder>/common/console.c) and it seems like the CONFIG_SILENT_CONSOLE only disables output. If you wish to disable input as well, there is another config (CONFIG_DISABLE_CONSOLE), which should do it.

I hope this helps.

Best regards,
Miroslav

Hi All,

              I have struck out with the problem in enabling the pr1_uart0  and specify  the step-by- step procedure to enable the pr1_uart0 in order to connect with the device.

Here is the pin details:

pins -  details

B16 - PR1_uart0_RXD

A16 - PR1_uart0_TXD

Kala,

Since you do not seem to be using BIOS but are trying to get some low level functionality working on a AM355x device, I have moved this thread over to the Sitara forum in hopes that you will get a faster response there.

To my knowledge, there is no existing Linux / Android driver support for the PRU UART.

Please note that the PRU UART interrupts are not directly accessible from the ARM.  For this reason, I do not expect the existing UART driver to support the PRU UART as is.  Instead, the PRU INTC would need to be configured to route the PR1_UART0 events to one of the PRU Host events corresponding to PRU_ICSS_EVTOUT0-7 in the ARM interrupt controller and the driver updated to use these interrupts.  More information about the PRU INTC is available here: https://github.com/beagleboard/am335x_pru_package

Regards,

Melissa