Cannot program custom board

RE: Cannot program custom board

Kaja — Tue, 08 Dec 2020 11:16:22 GMT

Hi!

I'm glad you found the issue, and a solution to you problem.

Best regards,
Kaja

RE: Cannot program custom board

dsmith115 — Mon, 07 Dec 2020 21:54:34 GMT

Hello! I have solved the issue.

For completeness, to answer your questions, the voltage on the reset pin was 3 V (same as VDD_nRF). I made a total of 2 boards (1 additional after removing C19 and L4).

I did not try powering V_sys directly - I was able to isolate the issue before getting to that test.

It turns out that when removing the nRF52840 from an existing board (which I am doing because of part shortages, new chips on backorder), the pads can actually become dislodged from the package if you are not careful!

Here is the pad SWDIO, still on the dev board:

And when you look at the bottom of the chip, you can see the missing pad (and another VDD pin that was missing):

So, after realizing this, I assembled another board, taking great care in the removal and addition of the nRF52840. And I have been able to program this new board and load up my blinky firmware!

Thanks for all the help provided.

RE: Cannot program custom board

Kaja — Mon, 07 Dec 2020 13:01:00 GMT

Hi Daniel,

could you measure the voltage on the reset pin?

How many boards have you tried to program, after removing C19 and L4?

Could you try to supply V_sys directly form a power supply insted of via the USB, and see if you're able to program it then?

Best regards,
Kaja

RE: Cannot program custom board

dsmith115 — Fri, 04 Dec 2020 15:19:37 GMT

Thanks I have removed both C19 and L4 with no effect. I am still unable to program the device.

I have also triple checked the debug connector. I am using the same 5x2 header with a 10 pin debug cable, connecting P1 on my board to P19 on the DK. Power is applied via USB to my board.

I will submit a new case for a design review.

RE: Cannot program custom board

Kaja — Fri, 04 Dec 2020 14:26:24 GMT

Remover C19 as well, and check your set up:
https://devzone.nordicsemi.com/f/nordic-q-a/20536/programming-external-custom-nrf52832-board-using-nrf52-dk

You make a new case private or public, depends if you want your design to be public or not; Headline; "Design review nRF52840".

Best regards,
Kaja

RE: Cannot program custom board

dsmith115 — Fri, 04 Dec 2020 13:31:21 GMT

Hi Kaja,

Thanks, I did catch that and remove L4 - no effect, still cannot program the board.

How can I submit the rest of my design for review?

RE: Cannot program custom board

Kaja — Fri, 04 Dec 2020 12:35:35 GMT

Hi Daniel,

you have connected VDDH to VDD and should therefore use normal voltage mode, and therefore remove L4 from your board.

https://infocenter.nordicsemi.com/topic/ps_nrf52840/power.html?cp=4_0_0_4_2_0_0#unique_1782262349

We offer free design review of both schematic and layout's here on DevZone, if you want us to check your design.

Best regards,
Kaja

RE: Cannot program custom board

hmolesworth — Thu, 03 Dec 2020 23:56:34 GMT

Ah, so much for a quick fix. Maybe Nordic will spot something; I'm assuming you can program another nRF52 device from your DK, by the way ..

As an aside, I leave USB pin 4 - Id - disconnected. Does it matter? Maybe not ..

RE: Cannot program custom board

dsmith115 — Thu, 03 Dec 2020 23:38:44 GMT

Thanks for your reply.

I'm not using DK to supply power to the board - it is either powered by USB or coin cell when attempting to program.

And also thanks for the part recommendation on the MAX40200!

RE: Cannot program custom board

hmolesworth — Thu, 03 Dec 2020 23:33:49 GMT

The circuit looks fine; I compared it with one of mine and the only difference I see is that I backdrive VDDH from VDD with a schottky but only because I have an option to power via higher voltage on VDDH; if that is not required direct connect is fine.

If using P19 on the DK to program, note pin 1 is not a 3.3 v supply to your board, if I recall correctly, it is a voltage sense. A separate 3.3 volt supply is required from the DK, typically jumper DK VDD to DK J19 pin 1 or solder a bridge on SB47 near J19. P20 can also be used but P19 with separate VDD link is probably preferred.

For your next board spin I would recommend replacing the two series schottky diodes with MAX40200 to avoid squandering significant battery capacity over the product lifetime - see MAX40200