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Bluetooth Booster Pack / Breakout board - HC05/HC06

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Just found out HC05 cannot work without the Key tied to ground (Pin34). The diagram shows a the pin with a pull down resistor of 10K, but somehow 10K is too much for it to work. What will be a safe value for a pull down? The pin needs to be pulled high for the module to go into command mode.


The other solution is to use a jumper and do away with the switch and resistor, since you only use the switch occasionally.


Appreciate if anyone can give me some advise.






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Fix 1 up for testing.   Since it is just a simple breakout board, it works pretty well.

BluePack BoosterPack PCB Wiki Link 43oh Store Link SeeedStudio Store Link   HI Guys,, I will be making a breakout board / Launch Pad booster pack for the Bluetooth module. This will be my first

Final.. I will not try to stuff the board to 50x50mm.  

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HI RobG,


HC05 will need Pin34 high on power up to put it into AT Command mode for programming, in normal use it needs to be tied Low. So will a jumper be better?


Looks R5 the reason they used 10k. You can safely use 1k to pull the pin down and you can also add a parallel resistor to the switch. Then you populate only one you need. For master you would not need switch. What do you think?
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decided to redo the whole board after all the comments and suggestions, learn more about PCB layout.


Changes made.

1. Removed extra foot print for LED and use trace jumper instead, so you solder what you need to connect the status LED.

2. Moved Module above and use copper pour for GND plane, for better placement and EMI shielding. (I think ..haha)

3. PCB cut out so that the trace antenna in exposed.

4. moved LED to the bottom layer but place it at the edge, so we can still see the light from LED.


here is capture of the brd.


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How do we switch TX/RX pin with this??

I am adding this in cause some MCU need to have Hardware UART pin switched on the LaunchPad.


Please advise thanks.




Hope to get it out soon. haha.


Since I still have some space on the 50x50mm board, I am going to add a logic level translator, again can be broken of if not needed.

Thinking of using TXB0104, don't know if I got the skills to make it work or not, maybe should just stick to this.




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