I was just now reading the hardware notes in the sketch, and it sounds like you are directly connecting the Arduino 5V TTL serial pins to the WT32i 3.3V CMOS serial pins.

If so, then you really should fix that. The datasheet for the WT32i clearly indicates that 5V is TOO MUCH INPUT VOLTAGE for any of its I/O pins.

So specifically, the TX line from the Arduino to the WT32i should get stepped down by 33%. The other line (TX from WT32i) is fine as-is.

Two resistors are needed for this: ideally 20K and 10K ohms, but lower K values will work so long as the 2:1 ratio is maintained (Eg. 10K and 5K). Or heck, even two resistors of the same value will work (Eg. 10K and 10K).

Connect the 10K to TX from the Arduino, connect the 20K to GND, and connect the other leads of each resistor to each other. The RX-input of the WT32i also gets connected to that same point (where the two resistors are tied together).

Click here to view the image full-size.

Cheers


Attachments
serial.jpg




Edited by mlord (08/12/2017 22:45)