no device detected, or readback protection may be set

[bscdb]

Hi,

I am facing the problem as shown in the image below for two PCA10040 and two PCA10028 boards. I read related posts but none of them helped!! I did not make any changes on the development kits in terms of hardware. I'm using the latest versions of all nrf softwares and using SDK 15.2.

[bscdb]

Okay so this got solved by connecting P0.21 to VDD. But why this has to be done? When I remove the connection it does not work.

[haakonsh]

p0.21 is the reset pin. For some reason it has a weak pull to GND. Normally it is the opposite, a pull to VDD.