Hello all,

I've bought myself a HC-05 module on a JY-MCU breakout board, but cannot
seem to find anything concrete about what the JY-MCU breakout board (stamped
ZS-040) does or needs.

The pinning:

STATE (out)
RXD \ 3.3v
TXD  /
GND \ 3.6 ... 6v
VCC /
EN (in)

Biggest problem: The voltages (in and out) of the EN and STATE pins.   Are
they 5v tolerant or is 3.3v the maximum for either (signal voltage or
pull-up).   And are the RXD and TXD pins 5v tolerant ?

Secondary problem: What is the EN pin connected to on the HC-05 module ?
What is it supposed to do ?

And some confusion: Why does the JY-MCU board have a voltage regulator at
all ? Now it can't connect to a pure 3.3v MCU, and when used with a 5v MCU
it needs logic-level conversion buffers for the communication.  That doesn't
makee much sense ...

Regards,
Rudy Wieser

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