Disable serial console

[Prakash Srinivasan]

Dear all,

I am trying to disable the default serial console and trying to use it for interfacing external serial GPS sensor. Similar query raised multiple times on different forums, but no proper solution provided. I found one from here, http://forums.wandboard.org/viewtopic.php?f=8&t=333 and here https://groups.google.com/forum/#!topic/wandboard/lg9cKfi4OD0. I tried with modified boot commandline under Boot option in kernel, applied the patch for drivers/tty/serial/imx.c, recompiled the kernal and disable the console option in uEnv.txt. But whenever I connect my external sensor on the serial port, the board failed to boot and hangs with wandboard logo. However, when I removed the external sensor and boot the board, I can get into android successfully. If I connected the external GPS sensor on serial port once android booted, I can able to get the gps datas without any issue. The only problem is it wont boot when it is attached the serial GPS sensor while booting.

Kindly help me to resolve this issue.

Thanks in adv,
Prakash.

[Matt Madison]

On Thursday, April 2, 2015 at 4:25:39 AM UTC-7, Prakash Srinivasan wrote:

Dear all,

I am trying to disable the default serial console and trying to use it for interfacing external serial GPS sensor. Similar query raised multiple times on different forums, but no proper solution provided. I found one from here, http://forums.wandboard.org/viewtopic.php?f=8&t=333 and here https://groups.google.com/forum/#!topic/wandboard/lg9cKfi4OD0. I tried with modified boot commandline under Boot option in kernel, applied the patch for drivers/tty/serial/imx.c, recompiled the kernal and disable the console option in uEnv.txt. But whenever I connect my external sensor on the serial port, the board failed to boot and hangs with wandboard logo. However, when I removed the external sensor and boot the board, I can get into android successfully. If I connected the external GPS sensor on serial port once android booted, I can able to get the gps datas without any issue. The only problem is it wont boot when it is attached the serial GPS sensor while booting.

Did you reconfigure U-Boot to disable bootdelay?  If not, then any stray input on the serial line would interrupt the boot at power-up.  See doc/README.autoboot in the U-Boot source tree for info.

-Matt

[Prakash Srinivasan]

Hi Matt,
    Thanks for your input. You mentioned the valid point. I modified CONFIG_BOOTDELAY with negative value and rebuild the u-boot. Its created u-boot.imx, u-boot.bin and few other files.However, the u-boot.img file is not generated which is required to copy into the boot partition. Many tutorials explained with u-boot.imx. But I could not find u-boot.imx file on the official android 4.4 .img. Any inputs from you?.

-Prakash