Length Check

[thewiseguyshivam]

Tried using this library with Raspberry Pi Pico, and I am sending serial data over USB. No matter how I format the text, it does not detect variables to show in the readings tab. I have a question about the length check - is that the issue? I don't understand how to use the length check part: what number should I write?

I added a line like this:
sys.stdout.write("Knobs,0.1,A201,,,LoadA:" + loadText_A + ",36" + "\n")

Here: loadText_A is a variable that can range from 0 to 65535. In that case the length of the variable itself changes. How do I decide the length check number? Please help.

[alexteaa]

The length check is checking the number of bytes written up until comma+length. Assuming you are using Python (MicroPython) and standard (utf-8) encoding for stdout, you can try:

def len_ck(message):
    bytes = len(message.encode('utf-8'))
    return "," + str(bytes)

loadText_A = "55"
message = "Knobs,0.1,A201,,,LoadA:" + loadText_A
sys.stdout.write(message + len_ck(message) + "\n")

It outputs for me:

Knobs,0.1,A201,,,LoadA:55,25

If you know that your string contains "standard" 1-byte chars (e.g. ASCII), you can just do len(message) instead of len(message.encode('utf-8')) to save cycles. Let me know if this is on a very hot path - would be interesting to figure out optimal solution :).

We should probably add device-side MicroPython lib (in addition to Arduino that is included already) to make this nicer. If at all helpful, here's log method one can use:

def len_ck(message):
    bytes = len(message.encode('utf-8'))
    return "," + str(bytes)

def log(message):
    sys.stdout.write(message + len_ck(message) + "\n")

log("Knobs,0.1,A201,,,LoadA:125")

(outputs Knobs,0.1,A201,,,LoadA:125,26).

Let us know if this works!

[thewiseguyshivam]

Yes, the len_ck method seems to work for me currently!

My major challenge was that the documentation was not able to tell me enough about length check part (https://github.com/sensortea/CupLogger?tab=readme-ov-file#data-format). Maybe add the above info there as well for newbies like me 😬

Clever work on the logger though, saved me days of work! 💯

[alexteaa]

Glad that it worked, @thewiseguyshivam. Updated README, thanx!
Don't forget to "star" if you find it useful :)