Hello,
I would like to use the ttyS0 as a general purpose UART. It is connected to the J50 header of the B01 version of the Nano Dev kit.
The first step is to disconnect it from the console, and I followed the instructions in the l4t documentation which says:
For NVIDIA® Jetson Nano™: Edit the platform configuration file p3448-0000.conf to remove the specification console=ttyS0.
The file p3448-0000.conf
calls the file p3448-0000.conf.common
which has the snippet console=ttyS0
. I removed it and then created an sd-card image using the tool jetson-disk-image-creator.sh
, with the correct board and revision information for my setup.
It however did not work, and the ttyS0 is still used for the console.
Indeed, it looks like the line console=ttyS0,115200n8
is appended by another script or file, prior to the file p3448-0000.conf.common
. This can be seen on the output from the console during boot, in the append
section:
U-Boot 2016.07-g0536cf2a27 (Dec 09 2019 - 22:40:32 -0800)
TEGRA210
Model: NVIDIA P3450-Porg
Board: NVIDIA P3450-PORG
DRAM: 4 GiB
MMC: Tegra SD/MMC: 0, Tegra SD/MMC: 1
SF: Detected MX25U3235F with page size 256 Bytes, erase size 4 KiB, total 4 MiB
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
Net: No ethernet found.
Hit any key to stop autoboot: 1 ^H^H^H 0
switch to partitions #0, OK
mmc1 is current device
Scanning mmc 1:1...
Found /boot/extlinux/extlinux.conf
Retrieving file: /boot/extlinux/extlinux.conf
733 bytes read in 169 ms (3.9 KiB/s)
1: primary kernel
Retrieving file: /boot/initrd
5487751 bytes read in 290 ms (18 MiB/s)
Retrieving file: /boot/Image
34191368 bytes read in 1538 ms (21.2 MiB/s)
append: tegraid=21.1.2.0.0 ddr_die=4096M@2048M section=512M memtype=0 vpr_resize usb_port_owner_info=0 lane_owner_info=0 emc_max_dvfs=0 touch_id=0@63 video=tegrafb no_console_suspend=1 console=ttyS0,115200n8 debug_uartport=lsport,0 earlyprintk=uart8250-32bit,0x70006000 maxcpus=4 usbcore.old_scheme_first=1 lp0_vec=0x1000@0xff780000 core_edp_mv=1125 core_edp_ma=4000 tegra_fbmem=0x800000@0x92cb4000 is_hdmi_initialised=1 root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=tty0 fbcon=map:0 net.ifnames=0 root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=tty0 fbcon=map:0 net.ifnames=0 quiet
## Flattened Device Tree blob at 83100000
Booting using the fdt blob at 0x83100000
reserving fdt memory region: addr=80000000 size=20000
Using Device Tree in place at 0000000083100000, end 00000000831776dc
Starting kernel ...
The snippet console=ttyS0,115200n8
occurs before the part console=tty0 fbcon=map:0 net.ifnames=0
which is set by the file p3448-0000.conf.common
.
Do you know which file or script is responsible for this? That way I could edit it out from the command line at boot, and access the ttyS0 to interface with my device?
Thank you for any help you can share.