I'm using the Ulink-ME tool in order to program/debug my custom board based on the nRF51822 device. The problem I have is that sometimes the flashing procedure is working fine but sometimes, when going to 'Option for Target...' --> 'Debug' --> Settings,... it says SWD communication failure, as shown in the picture... I try to reset the board, the Ulink-me tool,... but I have to try several times before it starts working again. Have you found any similar behaviour? Do you know which can be the reason of this problem? Are there any other pins (besides SWDIO, SWCLK) that are needed for the debugger/programmer to detect the micro or that should be placed at a certain level? It is very strange: I have several prototypes and they are mainly based on the schematics that appear on nRF51822 Product Specification. All of them have the same behaviour: sometimes I can program them and most of the times appear what it is shown in the image below. Then I remove batery from circuit, I remove ULINK-ME, and I reconnect everything again: after some trials doing that, I can program custom board again... Seems something related to any signal: I have tried the same wiht ULINK2 and I get same results.
