Electronic – Kiel debugger exits automatically

Atmel has a number of debugger / programmer pods available. For example, the JTAG ICE mkII, AVR ONE!, AVR Dragon, and JTAGICE3 all seem to support JTAG to some extent. You can get it from their store, and also through various distributors. I've never used any of them for JTAG, but JTAG debuggers typically give you the capability to do things like single step through your code and inspect / alter memory and register contents through your integrated development environment.

The nRF51822 dev kit has a J-Link programmer already on board that you can use for development. Not sure if this can be broken out to program other devices but it might be possible.

Beware of cheap imitations, since they will likely not work with the debug environment due to missing serial number.

More importantly, realize that if you're serious about developing products, you need the right tools. Don't waste time building a hack one and getting it to work unless that's what you want to focus on. Get the right tools and get to work.