I recently bought Freescale's FRDM-FXS-MULTI-B, and have been trying to integrate it with an Arduino UNO. The board descriptions say that it has the shield layout that matches that of an Arduino shield. So in theory, I should be able to integrate it fine.

The problem comes when I plug it in and try to program the Arduino. As soon as I plug it in, the board resets and hangs. If I try to upload a simple code (just reading the analogue signal from the light sensor), the IDE hangs when uploading. Sometimes, I can fix it by removing the shield and pressing the reset button, but sometimes that doesn't work: the computer doesn't recognise the Arduino on the port, and the IDE removes the port from the Port Selection option. When I do remove it and it resumes functioning normally, and I re-attach the shield, the board resets and hangs again, until I go into the Serial Monitor.

With this board, I realised the Bluetooth module is connected to the Serial Receive pin, which explains the hang in the IDE, but I cannot understand why it resets and hangs when I plug it in.

Does anyone have any experience with this board, and can help me out? Why can I not find any tutorials online? With the multitude of sensors on this shield, I'm guessing you can access them via normal I2C and SPI communications, right? How do you use the Bluetooth module on the board?

  • What are you using to tell that the sketch is hanging even when it isn't connected to the serial monitor? Commented Mar 4, 2015 at 17:02
  • @BrettAM The sketch compiles fine, but when it is uploading, it freezes and stays in the same spot for ages. If I do press the reset button on the board, I get the 'avrdude: stk500_getsync()' error, but sometimes the code uploads, sometimes not.
    – Tom
    Commented Mar 5, 2015 at 8:47

1 Answer 1


So... 20 months later I stumbled upon this question, only to find out I wrote it. Awkward! Anyway, for anyone who stumbles across this question in the future, here is the answer.

The Rx pin is connected to the Bluetooth module, and as such the module will keep the pin in an idle state (either idle-high or idle-low). The Rx pin of the Arduino UNO (or the Rx0 pin on the Mega/Due) requires to be free of anything that may interfere with the upload. The Arduinos rely on the Rx pin for the sketch upload. If anything is connected to it, the IDE will freeze and nothing will be uploaded. Simply disconnect the FRDM board, upload the code, and put the board back in place. Then it should work.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.