UART not sending data to FTDI USB

[Doug_H]

I can't get my PCA10040 board to send serial data when connected to a FTDI USB dongle. When the FTDI dongle is disconnected, and I connect my logic analyzer to the tx and gnd pins assigned on to the UART on the PCA10040 board it works perfectly. But as soon as I connect the FTDI dongle to the same pins, I get no serial data detected on the dongle and no serial data detected on the logic analyzer.

Any ideas what could be causing this?

This is the same dongle I use all the time on my STM32 boards and it works fine, so I know it's OK.

Here is a link to a photo of the setup: www.dropbox.com/.../IMG_5031.JPG

[endnode]

Maybe more details on how you exactly connect the dongle to the board? Are there some jumper wires between nRF52 GPIO header pins and your FTDI convertor? Do you have the system grounded properly? Maybe photo would help...

[Doug_H]

Yes, I'm using jumper wires. I have PCA10040 TX=P0.27, RX=P0.26. I added a link to a photo of the way the boards are connected in the original post

[endnode]

It looks OK. Simple test would be: use Tx/Rx pins attached to J-Link OB chip on the Dev Kit and see if SEGGER emulation of COM port works. If yes then it's most probably in your dongle or clumpsy wiring...

[endnode]

Also are you sure that Tx/Rx/GND wires are correct on the dongle? Just trying some trivial mistakes...;)

[endnode]

Are these Tx/Rx from the right point of view?;) Also is the dongle really 3V3 TTL UART?