OTA update of a new nRF51822

[MR2]

Hello,

I am currently designing a PCB containing the nRF51822 chip and I am concerned about how I will be able to update the program. I have 2 main questions :

1. I will have the PCB done and assembled by a PCB manufacturer. The nRF51822 chip will be ordered directly by the PCB manufacturer. There is no JLink connector on the PCB as there is no space for it (space is critical for my application). When I receive the PCB, will I be able to perform an Over the Air update directly? I need to load the S130 SoftDevice and of course my application program.
2. In the spec I see that the "SWDIO/nRESET" pin is active low. Does that mean that if I leave the pin unconnected (I don't plan to use the pins SWDIO and SWDCLK as I want to perform OTA update only) the nRF51822 will always be in debug mode or reset constantly? In the schematics and PCB layout I see that these 2 pins are connected. Can I leave them unconnected?

Thanks a lot in advance for your support! <3

[RK]

No - unless you have someone program the chip for you before assembly, or program the board with some kind of jig after assembly or you make some kind of small connector on the board which can be used for programming, you won't be able to program the chip. The chip comes entirely blank and SWD is the only way to get the initial code onto it.

nRESET/SWDIO is pulled high by an internal resistor so no you won't constantly reset. I've had noise problems in one of my applications (it's subject to some interference and the board design is not yet that great) and that's been pulling the nRESET low and resetting the chip, so tying it high is a good idea, as long as you leave some way to program the board first.

You should ask your board manufacturer if they can program the chip before assembly. There are programmers which will take unmounted chips (QFNs at least), put them in a socket and program them.

[RK]

well you'll need to get a programmer, and if this is commercial then you should get one which has a commercial license for programming (the on board JLink does not).

Tag Connect is here. They have a load of products, you need to read carefully and make sure you get the right one (or mail them, they're helpful). I'm using the 10pin footprint on my boards and have the cable which connects it to a Segger JTAG, one of the full-sized ones with a 20-pin .1" pitch connector on it. They also have a cable which attaches to the 10 pin FTSH (the debug out on your dev kit board) to either the 6 pin or the 10 pin board footprint connector. I believe the 6-pin, they claim, takes up 1/3 the space of a standard ARM 10 pin 0.05" connector.

Go take a look at those products and the footprints, see if you think it'll fit, and ask again when you think you've picked one.