Baudrate auto-detection

[ebnerluca]

When I connect a ublox device to the official u-center software, I don't have to specify the baudrate as it will just iterate through all possible baudrates to find the correct one. I would like to see the same feature integrated in this driver.

This driver could offer the option to set the uart1/baudrate to auto instead of just a number.
If this is detected, the node at start would simply try to listen to the port for some target message (e.g. UBX-MON-VER) with the desired baudrate and if successfully received, use the current rate. If not received, try the next baudrate.

Has anyone ever done something like that?
A quick & dirty prompt search gave me the following snippet to give an example of the logic I am imagining. Beware that this snipped is untested:

#!/bin/bash

DEVICE="/dev/ttyACM0"  # Change this to match your serial device
BAUD_RATES=(9600 19200 38400 57600 115200 230400 460800 921600)
UBX_MON_VER_HEX="b5620a0400000e34"  # UBX-MON-VER polling message

function send_poll() {
    local baud=$1
    echo "[*] Trying baud rate: $baud"
    
    # Send UBX-MON-VER polling message and listen for reply
    timeout 2s socat -T1 -d -d \
        "EXEC:echo -ne \"$(echo $UBX_MON_VER_HEX | sed 's/../\\x&/g')\",pty,rawer" \
        "PTY,link=/tmp/vserial,rawer" 2>/dev/null &

    sleep 0.5

    # Set baud rate and read output
    stty -F $DEVICE $baud raw -echo
    head -c 200 < $DEVICE | hexdump -C > /tmp/ublox_resp_${baud}.txt &
    PID=$!

    # Wait and kill if still running
    sleep 1.5
    kill $PID 2>/dev/null

    if grep -q "b5 62" /tmp/ublox_resp_${baud}.txt; then
        echo "[+] UBX response found at baud rate: $baud"
        return 0
    else
        echo "[-] No UBX response at $baud"
        return 1
    fi
}

for rate in "${BAUD_RATES[@]}"; do
    if send_poll $rate; then
        echo "✅ Detected baud rate: $rate"
        exit 0
    fi
done

echo "❌ Failed to detect baud rate."
exit 1