Actions
Forum Thread Details
  • State Suggested Answer
  • Replies 7 replies
  • Answers 1 answer
  • Subscribers 48 subscribers
  • Views 1990 views
  • Users 0 members are here
Related

Some garbled serial comms from Micro:bit

pmulvey

My Serial writes are garbled when sent out to TeraTerm terminal program but Ok when viewed on the Serial monitor. Characters get dropped. This is quite useless as I want my class to receive the data in Python on the PC. I get this in both micro:bit Python editor and MS Makecode. I have used different micro:bits on different PCs, same result.

I tried Mu Editor and the micro:bit sends data across the serial port perfectly. I'm using V2. Is there an issue with the firmware used by MS Makecode and micro:bit Python editor?

I wrote a short Python program to read the serial port on the PC and I get the same results as with TeraTerm i.e. dropped characters, about 10% only, no major garbling.

 

Parents
  • 0

    Are you sure you are matching the correct baud-rate, parity, bit-length and stop-bits? This needs to match what is used by the program running on the Micro:bit and should match whatever serial monitor you were previously using. Common rates include 9600bps, 19200bps, 38400bps, 57600bps and 115200bps (this seems to be a Micro:bit default). Usually 8-bits, no parity, 1-stop-bit is customary.

    Have you ensured compatible flow-control is set? Usually, without dedicated handshaking lines, None should be used. If it is set to XON/XOFF, this could result in some unpredictable behaviour, while setting it to RTS/CTS without the lines connected could inhibit communications entirely.

    Are you only sending printable characters? As there are some escape sequences which can really "stuff up" terminals and cause them to change modes/display garbled data.

    - Gough

  • 0 in reply to Gough Lui

    I have used TeraTerm and Python as the receiver of serial data from ESP, Pi Pico and Arduino and I have seen the garbled output from unmatched serial settings. Interestingly this seems to be down to dropped characters or most likely characters not sent as I don't get hardly any wrong characters. When using the MU Editor and the firmaware that it loads on to the microbit everything is OK, all characters are transmitted fine. I have tried putting a 20mS pause between each character of a string but same result.

  • 0 in reply to pmulvey

    Can you attach example images, code, settings, results etc?

    We can't help you if you can't help us understand the issue you're facing in more detail. I'm not sure what you mean by dropped characters - if it's serial overflow, that is a possibility but still unlikely as serial is "slow" compared to the speed of modern computers.

    - Gough

Reply Children