nRF52832 module is outputting 0.59V. Is the module broken?

[TomWS]

I am bringing up a breakout board for an nRF52832 module (MDBT42Q) and can not get a response from the module.  The breakout board has very little circuitry, mostly fanout of IO pins.  It does have a 1.0uF capacitor on the DEC4 pin and I'm trying to communicate with a J-Link SWD interface, but get no response.  When I measure the DEC4 pin, I see approximately 0.59V.  Using a scope the pin appears to be ramping between 840mV and 500mV at about 147Hz.   I do not have inductors between DCC & DEC4 pins installed on the board.

Is this module broken?  I have the reset pin tied high and approximately 3.15V VDD.

Tom

[tBStar]

It's hard to say, did you solder the custom board yourself or sold as is? DCC and DEC4 are not needed to program the module, just make sure the module and your J-link programmer are powered independently with 3.3V and your Reset is not grounded.

How are you powering your module to get 3.15V?

[TomWS]

I made the breakout PCB and soldered it myself.  The board is powered from a CR123 battery.  I inspected the solder joints pretty thoroughly and they look fine.   This module has 1mm pin pitch so it isn't especially challenging to solder.

As I said, I've pulled the Reset pin high.  It bothers me that the unloaded DEC4 pin (other than 1uF cap) is reading 0.59V.  It's supposed to be 1.3V as I understand it.

The J-Link VCC pin is connected to VDD rail, but, as far as I know, that's only to confirm power at the test board.

I've measured the voltages right at the module pins.

[tBStar]

I've hand-soldered an MDBT42Q BLE module in the past, at least for me, it was nontrivial. I ended up solder join  couple of non-essential pins but overall still workable with a 1.3ish V on DEC4. The only thing different I have is an LDO with 2 Caps since I am using Lipo battery. Other than, I have nothing else on the board. I was able to load Espruino on it with Segger J-Link without issues.

Try to power the module with a 3V coin cell without connecting anything to it and measure the DEC4 again. If you don't see 1.3V, that means 2 things: #1: you have joins that you missed or #2: the module is defective.

Good luck

[TomWS]

Yes, I'm thinking that the module broke during reflow soldering even though the temp didn't go above 218C.  The module hasn't been sealed and I've had it in my office for a while.  I probably should have baked it before reflow.  As you suggest, I'll hand solder the next one (at least the few necessary pins) and see what I get.  As you say, soldering together a couple of unprogrammed pins won't hurt anything.  Thanks for the advice, I'll report back after I've tried it (will probably be tomorrow  US EST).

[tBStar]

To increase your chances of success, use 0.3mm solder with a lot of flux. Keep in mind the module doesn't come with an external 32.768 kHz RC oscillator which is optional. Once your get the module working, you will need to make some configuration changes to use the internal RC oscillator instead if you're planning not to use one. The only thing I can think of is setting NRFX_CLOCK_CONFIG_LF_SRC to 0 in your sdk_config.h for now. We will cross that bridge when we get to it. Good luck

[TomWS]

Eureka! Handsoldering did the trick.  I've got 1.3V at DEC4 AND I'm able to access the chip using J-Link and nRFGo Studio!  I managed to solder the 4 gnds, VDD, DEC4, XL1, XL2 (I do have an on-board 32.768KHz crystal), and the two SWD signals.

As you said, it wasn't trivial.  I needed a VERY fine tip on the soldering iron and dabbed T4 solder paste on the joints to prime them.   It turns out the module did have the S132 soft device installed on it but no application or bootloader as far as I could tell.

Thanks for your help and confirmation of my suspicions...

[TomWS]

Just as a follow up, I used the solder paste technique and was able to successfully solder all the pads on the MDBT42Q module and now have a fully functioning breakout board that is currently emulating the NRF52 DK board.  Great forum!