I have a PAN1640 USB stick dev kit, I add short wire on the pad for testing. I use a serial com at 9600 and DSPS.
I assume noise can't come from bluetooth com, you confirm ?
- if I make a com between the ATmega and PAN1640 module with my wire floting I have noise
- if I make a com between an external chip and the PAN1640 module with my wire I have noise
The external chip is a PIC16 and with an USB to UART dongle it have no noise.
Some packet was OK but some other have big noise, if I touch anything and the sensor is made in plastic.
I can't make a try with removing my wire, It's a small work and too many reflow can easylly damage the dev kit. But slow baudrate not so sensitive to noise...