How to read data from serial and process it when a specific delimiter is found

I have a device, which continues to send data over a serial port.
Now I want to read this and process it.
The data send this delimiter "!" and
as soon as this delimiter appears I want to pause reading to processing the data thats already been received.
How can I do that? Is there any documentation or examples that I can read or follow.

For reading data from a serial port you can find a few packages on Github, e.g. tarm/serial.

You can use this package to read data from your serial port. In order to read until a specific delimiter is reached, you can use something like:

config := &serial.Config{Name: "/dev/ttyUSB", Baud: 9600}

s, err := serial.OpenPort(config)
if err != nil {
    // stops execution
    log.Fatal(err)
}

// golang reader interface
r := bufio.NewReader(s)

// reads until delimiter is reached
data, err := r.ReadBytes('\x21')
if err != nil {
    // stops execution
    log.Fatal(err)
}
// or use fmt.Printf() with the right verb
// https://golang.org/pkg/fmt/#hdr-Printing
fmt.Println(data)

See also: https://stackoverflow.com/questions/17599232/reading-from-serial-port-with-while-loop

bufio's reader unfortunately did not work for me - it kept crashing after a while. This was a no-go since I needed a stable solution for a low-performance system.

My solution was to implement this suggestion with a small tweak. As noted, if you don't use bufio, the buffer gets overwritten every time you call

n, err := s.Read(buf0)

To fix this, append the bytes from buf0 to a second buffer, buf1:

if n > 0 {
    buf1 = append(buf1, buf0[:n]...)
}

Then parse the bytes stored in buf1. If you find a subset you're looking for, process it further.

• make sure to clear the buffers in a suitable manner
• make sure to limit the frequency the loop is running with (e.g. time.Sleep)