First steps with custom boards

[stunt_man]

I was looking for something like a checklist of what to do when developing on a custom board but I couldn't find it.

I am working with Keil 5.15. I achieved to develop some code (focus on BLE communication) on nRF51822 Evaluation Kit. No problem with it. I just got it right.

Now, I have got my custom board design included a nRF51822 SoC. My first try was to get basic tutorials OK with this board (I just want my board to advertise).

For board support, I write my own header file to define the I/O pins I am using and update my compilation options to use it. I can program my board and flash it without problem. Unfortunately board is not advertising. I add a virtual COM port to debug, connect to it but was enable to get any message.

Using J-Link Commander, I can see that Cortex-M0 is identified. Voltage is at 1.783 V

I had a look in nRFGo Studio and my custom board is not detected. Is it the first thing to fix? How? What are the next common steps ?

[Nick Pelis]

Your VDD seems both really low and odd. The minimum operating voltage for the nRF51 is 1.8V (from the product specification v3.1, chapter 7 "Operating Conditions"), so you're definitely out of spec. You didn't say what your design voltage was or what other components were on your custom board, but depending on your power path you might have a short somewhere. For instance if you have a short, that can overload a voltage regulator, causing your voltage to crash. What kind of current load does your board have?

[stunt_man]

Hi Nick,

Thank you for your comment. In fact, for this custom board, I use low voltage mode (1.8V). As explained in the product spec, DEC2 is connected to VDD (1.8V).

To get this voltage from J-Link, a custom adapter is put between J-link & PCB. J-link provides a 5.0V voltage (checked with voltmeter). PCB gets 1.8V (the forementioned 1.78V voltage - checked with voltmeter).

I found two interesting questions on this forum that could help: devzone.nordicsemi.com/.../ devzone.nordicsemi.com/.../

I'm going to further investigate!