nrf52832 ble problem

Question

I have designed nrf52832 customized board with tace antenna antenna and every pin of the controller is connected to the male headers present on both side of the boards. I havent used lpkf , so I changed the sdkconfig.h file to use internal RC but it wasnt working. By mistake , the P0.07 pin gets connected to Vcc and the led start blinking i.e. the bluetooth is advertising. Now ble is working fine but everytime I have to connect this P0.07 with 3.3v or also with little variation on that pin (like when I Just touch that pin with my fingers). I want to kmow that P0.07 is just an I/o pin , so why this behaviour? DOes it mean there is problem in my layout design. 
 There is no problem in the code as I'm using the standard code of ble of nrf52 dk by changing the sdkconfig.h as we dont have lpkf

AmbystomaLabs · Accepted Answer

Well broken ground plane seems to be your problem. 
 As I show in the following image you have essentially isolated the ground of the nRF from the rest of the circuitry. This is very, very bad. It looks like the nRF might have a sliver of a ground connection at C7, C8 but even that is marginal. 
 The way you have done the layout on your board none of the local capacitances are really doing anything since they are not connect to the same ground as the nRF. 
 As to why it works when you hook up the gpio, some level of physics magic is happening. Perhaps you are stabilizing the ground reference with that connection. 
 For starters to prove to yourself that is the problem, solder some 30 gauge wires across your broken bottom layer in a few places and the problem should go away. But you are going to have to redo your layout to fix it. 
 I recommend you pass your updated layout by me for review when it is ready. 
 Bridge the ground like this and see if it starts working. Just scratch off some of the solder mask to connect the wires. Use really small gauge hookup wire, like 30 or 32 even 40 gauge is fine. On the Vss connection at pin 45 you can probably bridge it with a little dab of solder. Just be careful not to short the pins. If this connection scares you, then do the others first and see how it goes.

AmbystomaLabs · Answer

It is normal for microcontrollers to source power through their gpio. Both the FET and ESD diode structure contribute to this. For this reason all gpio connected devices need to see the same voltage levels either by running them all on the same supply or using a combination of level shifters and/or open drain devices with pull ups.

nrf52832 ble problem

Top Replies