I have an HC-05 Bluetooth module attached to an Arduino Mega; the module is paired with a Raspberry Pi and fed data via a python program; there's roughly one send and one receive per second of about 35 bytes.

When I first power up the Arduino / HC-05, it flashes quickly, and then after pairing, it flashes twice every second indicating a successful pair & communication. All is good; data is flowing. Periodically (5 minutes? 3 hrs?) & unpredictably, the communication ends; I'm still trying to troubleshoot this; the python code on the RPi reports a not-helpful OSError: [Errno 5] Input/output error on the available() method of the pySerialTransfer library; though I welcome thoughts on that, I realize that question isn't for this forum.

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/pi/.local/lib/python3.7/site-packages/pySerialTransfer/pySerialTransfer.py", line 416, in available
    if self.connection.in_waiting:
  File "/home/pi/.local/lib/python3.7/site-packages/serial/serialposix.py", line 467, in in_waiting
    s = fcntl.ioctl(self.fd, TIOCINQ, TIOCM_zero_str)
OSError: [Errno 5] Input/output error

The HC-05 module continues to flash as if it's connected, even though it is not, and even if I restart the python program, I'm unable to repair with the HC-05. The only way I can figure out to reconnect to the HC-05 is to power the Arduino / HC-05; then I can reconnect.

So here is the question: is there to reset the HC-05 from within the Arduino sketch? I realize I could attach the VCC to a digital pin to do a full power cycle on the HC-05, but I believe the HC-05 draws on the outer limit of safe current for an Arduino (40ma); I could go thru a relay to do the disconnect, but I wonder if there's a cleaner way with fewer moving parts, or if that is indeed the best way?

Thanks for any guidance!


1 Answer 1


You could use a logic level MOSFET with low RDSon (e.g. IRLZ44) to switch the supply of the HC-05 and use a digital pin to control it.

  • Thank you - I've ordered a few of those and will give it a shot!
    – David W
    Commented May 25, 2020 at 23:39

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