are there any plans for NRF52 USB development dongles (just like the NRF51 dongle)?
Just a short help if you try to use the "ABSniffer USB Dongle 528" as nRF52 Dongle. To program the nRF52 you need to connect the J-Link to the pins marked in the picture below.
I also had success reprogramming the ABSniffer USB Dongle. Note that there's actually 4 pads in a row used for programming (the GND and VCC pads to the bottom-left of the SWCLK and SWDIO pads). If you contact April Brothers via email, they will sell you the POGO-pin assembly they use to program the device ($8 per + $6 shipping). If you plan on programming several, this may be the better solution. See photo of the assembly here: i.imgur.com/cPDdzFa.jpg
Or if you want to make your own assembly, the pads are designed for a 5-pin 1.27mm pitch POGO pin assembly (middle pin not connected, sits between VCC and SWCLK pads).
Did you flash sniffer_pca10040_51296aa.hex according to nRF_Sniffer_User_Guide_v2.0.pdf ?
Thanks Adrian Eggenberger, that was helpful. I did a little write-up of flashing the dongle with custom firmware (in this case iBeacon) here, if you're interested:
Kudos to AprilBrother for allowing and documenting it!