I have a python script that is supposed to run a Linux update on an iMX6 device. I can reboot Linux via serial connection. I can see the device rebooting (console output is transferred). However, when I encounter the line "Hit any key to stop autoboot:" in the serial output, a write command seems to get ignored.
import time
import serial
def reboot_and_update(port, baudrate=115200):
# Open the serial connection
ser = serial.Serial(port, baudrate, timeout=1,
bytesize=serial.EIGHTBITS, xonxoff=True,
parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE)
print(f"Connected to {port} at {baudrate} baud. Output:")
ser.write(b"reboot\r") # Send the command
try:
while True:
# Read a line from the serial port
line = ser.readline().decode('utf-8').strip()
if line:
# Print the received line to the console
print(f"{line}")
# Check for the specific line to trigger actions
if "Hit any key to stop autoboot:" in line:
print("Interrupt autoboot...")
time.sleep(0.1)
ser.write(b"345ju\r")
time.sleep(1)
ser.write(b"run install_linux_fw_sd\r") # Send the command
# Check for the login prompt and wait 3 seconds
elif "ccimx6ulsbc login:" in line:
print("Login prompt detected. Waiting for 3 seconds.")
time.sleep(3)
# If nothing else happens, close the connection
additional_line = ser.readline().decode('utf-8').strip()
if not additional_line:
break
else:
# Print any additional lines received during the wait period
print(f"Received after login prompt: {additional_line}")
else:
time.sleep(0.1) # Small delay to prevent busy waiting
finally:
ser.close()
print("Finished")
The output I receive:
(py312) C:\...>python serialconn.py
Connected to COM5 at 115200 baud. Output:
reboot
Broadcast message from root@ccimx6ulsbc (ttymxc4) (Fri Mar 9 14:41:36 2018):
The system is going down for reboot NOW!
INIT: Switching to runlevel: 6
INIT: Sending processes configured via /etc/inittab the TERM signal
root@ccimx6ulsbc:~# Stopping syslogd/klogd: stopped syslogd (pid 639)
stopped klogd (pid 642)
done
Stopping Dropbear SSH server: stopped /usr/sbin/dropbear (pid 661)
dropbear.
Stopping bluetooth: bluetoothd.
Stopping Busybox ACPI daemon: done
stopping Busybox HTTP Daemon: httpd... no httpd found; none killed
Stopping Busybox NTP client/server: done
Stopping system message bus: dbus.
ModemManager[739]: <warn> could not acquire the 'org.freedesktop.ModemManager1' service name
ModemManager[739]: <info> ModemManager is shut down
Stopping HOSTAP Daemon: hostapd.
Stopping tcf-agent: OK
ALSA: Storing mixer settings...
Unmounting remote filesystems...
Deconfiguring network interfaces... done.
Stopping NetworkManager: done
Stopping vsftpd server: done
Sending all processes the TERM signal...
Sending all processes the KILL signal...
Deactivating swap...
Unmounting local filesystems...
Rebooting...
U-Boot dub-2020.04-r7.1+gaf77921f51 (Jan 30 2024 - 12:53:20 +0000)
CPU: i.MX6UL rev1.2 528 MHz (running at 396 MHz)
CPU: Industrial temperature grade (-40C to 105C) at 68C
Reset cause: POR
DRAM: 1 GiB
MCA: HW_VER=1 FW_VER=1.14
PMIC: PFUZE3000 DEV_ID=0x30 REV_ID=0x11
NAND: 1024 MiB
MMC: FSL_SDHC: 0
In: serial
Out: serial
Err: serial
Model: Digi International ConnectCore 6UL SBC.
ConnectCore 6UL SOM variant 0x04: Industrial Ultralite 528MHz, 1GB NAND, 1GB DDR3, -40/+85C, Wireless, Bluetooth
Board version undefined, ID undefined
Boot device: NAND
Net: FEC0 [PRIME]
Fastboot: Normal
Normal Boot
Hit any key to stop autoboot: 0
Interrupt autoboot...
ubi0: attaching mtd4
ubi0: scanning is finished
ubi0: attached mtd4 (name "linux", size 24 MiB)
ubi0: PEB size: 131072 bytes (128 KiB), LEB size: 126976 bytes
ubi0: min./max. I/O unit sizes: 2048/2048, sub-page size 2048
ubi0: VID header offset: 2048 (aligned 2048), data offset: 4096
ubi0: good PEBs: 192, bad PEBs: 0, corrupted PEBs: 0
ubi0: user volume: 1, internal volumes: 1, max. volumes count: 128
ubi0: max/mean erase counter: 15/11, WL threshold: 4096, image sequence number: 0
ubi0: available PEBs: 0, total reserved PEBs: 192, PEBs reserved for bad PEB handling: 8
Loading file 'boot.scr' to addr 0x80800000...
Done
## Executing script at 80800000
## Loading kernel: zImage-ccimx6ulsbc.bin
...
So, seems like any input during the boot is somehow ignored.
I have tried to do the same thing with PuTTY, here it works. I have copied all the connection settings to my python script (but even with xonxoff disabled, it didn't work).
Can anybody help me here?
xonxoff=False. line = b''
uboot = 0
prompt = b'=>'
try:
while True:
# Read a line from the serial port
char = ser.read()
if char == b'':
continue
if char[0] == 13:
# Print the received line to the console
print(f"{line.decode('utf-8').strip()}")
line = b''
line += char
# Check for the specific line to trigger actions
if uboot == 0 and b'Hit any key to stop autoboot:' in line:
print("Interrupt autoboot...")
ser.write(b'\r')
uboot = 1
elif uboot == 1 and prompt in line:
ser.write(b"run install_linux_fw_sd\r") # Send the command
uboot = 2
# Check for the login prompt and wait 3 seconds
elif uboot == 2 and b'ccimx6ulsbc login:' in line:
print("Login prompt detected. Waiting for 3 seconds.")