I've bought the chip HC06 (without the breakout board, only the chip itself). I've followed the datasheet and I've done the following connections:

HC06 - Schematic

Datasheet of the chip that I'm using: https://www.olimex.com/Products/Components/RF/BLUETOOTH-SERIAL-HC-06/resources/hc06.pdf

However, when connecting to it via bluetooth, after a few seconds the HC06 always drops conection. Sometimes the LED stops blinking even though there is no device connected to the bluetooth module. At first I thought it was power supply issues, but I've noticed the bluetooth module is being supplied with 3.3 V (which is fine) and the amount of current from the power supply is at maximum 120 mA (not very high, as it is powering up some other modules as well). Any suggestions why it is not working properly?


I reverse-engineered a HC06 board, and it was following the following schematic:

enter image description here

But even when reproducing the same wiring in my PCB, the problem still persists. So I think the problem is either the chip itself that I am using (might be already buggy) or it is a problem with layout of my pcb.

  • \$\begingroup\$ HC06 seems to be a module, do you have a link to the chip datasheet? \$\endgroup\$
    – Damien
    Commented Jul 5, 2021 at 5:50
  • \$\begingroup\$ olimex.com/Products/Components/RF/BLUETOOTH-SERIAL-HC-06/… \$\endgroup\$
    – Samuel
    Commented Jul 5, 2021 at 14:24
  • \$\begingroup\$ What I'm trying to do is basically reproducing the HC06 module, but I got this problem. \$\endgroup\$
    – Samuel
    Commented Jul 5, 2021 at 14:50
  • \$\begingroup\$ Have you tried adding a WAKEUP on PIO3? \$\endgroup\$ Commented Jul 5, 2021 at 18:37
  • \$\begingroup\$ Tried to use the wakeup on PIO3 and it keeps disconecting... :( \$\endgroup\$
    – Samuel
    Commented Jul 5, 2021 at 20:45

1 Answer 1


Looking at the datasheet on page 6, it shows that pin 22 is connected to ground. It also has a strong external pulldown on pin 11 with (half) a capacitor (C4) to provide delayed power-on reset. And from page 7 of the datasheet, it says that it has a weak internal pulldown on pin 11.

For pin 22, is LED_CON in your schematic the same as GND in the datasheet?

HC-06 datasheet, page 6

HC-06 datasheet, page 7

  • \$\begingroup\$ Thanks, I connected the pin LED_CON to ground and I added a 400 nF capacitor to provide delayed power-on reset. I still have the same issue though. :( \$\endgroup\$
    – Samuel
    Commented Jul 5, 2021 at 23:53
  • \$\begingroup\$ Any other suggestions? I can't thinkg anything else besides changing the chip itself... \$\endgroup\$
    – Samuel
    Commented Jul 5, 2021 at 23:58
  • \$\begingroup\$ @Samuel, what about using pullups/pulldowns on all unused inputs to stop them floating? I've used these kind of chips before. They tend to be hit-and-miss whether they work. Cheap enough to replace though. \$\endgroup\$
    – tim
    Commented Jul 6, 2021 at 0:14
  • \$\begingroup\$ @Samuel, what about decoupling capacitors across the power pins? The datasheet doesn't mention anything about them. Perhaps you can reverse engineer an existing board module. \$\endgroup\$
    – tim
    Commented Jul 6, 2021 at 11:08
  • \$\begingroup\$ I will try to do the reverse engineering thing tonight. I'll let you know. \$\endgroup\$
    – Samuel
    Commented Jul 6, 2021 at 13:24

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