Serial Port Demo

Hi Devs,

Looks like the production batch of the newest developer tools, v.10.2020 Developer Tools, shipped with a cable that need fixing :man_facepalming:. Two wires got reversed, but luckily there is a quick fix. The Serial board has a Red/Yellow/Blue cable attached to it and we can fix the cable with some scissors and tape.

  1. Simply cutting the Yellow and Blue wires (not the red one, never cut the red wire :joy:)
  2. Strip the Yellow and Blue wire ends (4 in total)
  3. Twist the Yellow with Blue and then Blue with Yellow
  4. Tape over those two new connections (ideally with electrical tape)

That should do the trick. We’ll post more materials soon, but this will explain why the Serial connection has not yet been working.

Here is a video of the fixed wire working with the Serial Port.

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Does the Serial connection load the program on the blink back to the computer? I am not really sure what it does.

Great question. The Serial connection allows of bi-directional communication between the Blink and the computer. Part of the library is a serial API for printing debug messages to the serial viewer in Arduino is just one of the use cases.

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Thanks for this. I was able to get the serial port working with this guide. Thankfully I’d recently did the exact thing to a PSU fan recently, so it was a breeze. Now I can finally conduct diabolical experiments.

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Is there any reason you wouldn’t recommend releasing the pins from the connector and reversing BLUE/YELLOW? I did that instead of cutting and it seems to work fine, and that beautiful little spudger you sent along worked great.

BTW, first rate dev kit, and awesome support! Thank you very much for all the hard work! The only problem I have is wresting the blinks out of my son’s hands to test new builds. :slight_smile:


Hi there,

I did the same as you, it seems to work fine as well.
However the inverted side have to be on the serial porte adapter for it to work properly.

I did the same and can also confirm that this method works. :+1: Glad it was something simple!

Took about 30 seconds using the spudger. Works great.

For anyone who is not clear on how it works: the white plastic connector has 3 little “tongues” on one side that hold in place a little metal protrusion. Using the pointy end of the spudger (the black plastic tool that ships with the dev kit) gently lift the white tongue to release the pin corresponding to the blue wire, and pull out the wire by pulling on it. Do the same with the yellow. Insert the pins back into the connector with blue on the outside and yellow in the middle. Note the orientation of the pin going in, the little protrusion that latches is really tiny.


I’m still not able to get the serial port working. :pleading_face: I cut the wire and spliced blue to yellow and yellow to blue. I can see the port (/dev/cu.usbserial-A50285BI), and serial communication works with an Arduino. I’ve tried uninstalling and reinstalling the drivers (and disabled the Apple FTDI drivers), rebooted with the board both plugged in and unplugged, tried every baud rate, but still nothing when I try to run the Serial examples. It’s connected like: USB Cable -> TinyISP -> dev Blink -> serial cable -> serial adapter -> FTDI Connector -> USB Cable. The red led on the FTDI adapter is on.

I’m running a Mac with High Sierra and Arduino 1.8.13. Any other ideas on what to try? I really can’t get my game going and need a debugger at this point. Thank you!


OK, got it working, but it’s wonky. I plugged in the FTDI connector first, then connected the Blink, connected the Tiny, unplugged the Tiny, got a mess of characters on the monitor, plugged the Tiny back in, then got expected output. Weird, but at least it works now. :sweat_smile:

The serial port is not needed for downloading programs, it is only used as a way to let you interact with the running over the link. So you can put a print statement in the blinks program and have it displayed in the serial on your computer. You can also type into the serial window on the computer and have the program running on the blink read what you input. You can also do more advanced stuff like having the blink transmit real time telemetry back to a computer that logs it. Or have some blinks act like a music keyboard by transmitting midi messages over the serial link.