issues when flashing a custom board using nrf52833dk debug port P19

RE: issues when flashing a custom board using nrf52833dk debug port P19

Kaja — Wed, 07 Dec 2022 10:16:31 GMT

Okay,

no wo don't have any recommendations on this.

See our DF info and DF central ex , DF connection less locator and DF connectionless beacon,

our example is with a 12 patch antenna matrix.

Best regards,
Kaja

RE: issues when flashing a custom board using nrf52833dk debug port P19

George Shaker — Tue, 06 Dec 2022 16:38:38 GMT

Hello,

Thank you for reviewing the design and providing feedback. We have done the suggested changes.

Yes, this design will be used for AoA application and we will be using custom 4-Antenna Array with this board. The Antenna feed points are 30.6 mm apart and all four antenna are having the same structure.

Do you have any guidelines or any recommendations for the Antenna Array for AoA application?

Thanks.

RE: issues when flashing a custom board using nrf52833dk debug port P19

Kaja — Mon, 05 Dec 2022 13:41:23 GMT

Hi,

I will cover for Jared on this case today.

This looks better but some feedback:
1. Can you route the connection between the DEC4 and DEC6 so that it does not go under the 32 MHz crystal routing, and not spilt up the center pad of the nRF?
2. What types of antennas will you use? Is this meant to be used for AoA? What will be the spacing between the antennas?

[quote user="GShaker"]1) To access reset signal we have connected it to pin AD12 and fanned it(reset) out through that pad. Is that OK to do or will it cause any issue while programming the boards? The other thing we can do it cover that pad with solder mask or remove it entirely from the footprint. Do you have any previous knowledge of such implementation in any designs?[/quote]

- See pin reset in the ps

[quote user="GShaker"]2) We are planning to operate the design in high voltage mode, i.e. VDDH powered, what should be the supply connected to cJTAG programming header in that case? VDDH or VDD? My understanding is that VDD will be disabled in high-voltage mode. Is that correct or VDD will be regulated internally through nRF52833?[/quote]

- If your planning to use high voltage mode, when you need to change the configuration on the VDD/VDDH set up and use Circuit configuration no. 4 schematic for QIAA aQFN™73 as reference.
- VDD should be connected to the JTAG

Best regards,
Kaja

RE: issues when flashing a custom board using nrf52833dk debug port P19

George Shaker — Sun, 04 Dec 2022 23:00:08 GMT

Hello Jared,

We are done making the changes for the design. Can you please do a review of the new design for all nRF52833 related aspects for both schematic and layout? Schematic PDF and PCB layout file are located at: drive.google.com/.../1r2U6VuMSvopTMpycXYjjW5caeOkVX0NH

Also, we have two questions on the design:

1) To access reset signal we have connected it to pin AD12 and fanned it(reset) out through that pad. Is that OK to do or will it cause any issue while programming the boards? The other thing we can do it cover that pad with solder mask or remove it entirely from the footprint. Do you have any previous knowledge of such implementation in any designs?

2) We are planning to operate the design in high voltage mode, i.e. VDDH powered, what should be the supply connected to cJTAG programming header in that case? VDDH or VDD? My understanding is that VDD will be disabled in high-voltage mode. Is that correct or VDD will be regulated internally through nRF52833?

Thanks.

RE: issues when flashing a custom board using nrf52833dk debug port P19

George Shaker — Fri, 02 Dec 2022 15:58:18 GMT

Hello, thank you for the review and providing feedback. We are going to make some changes in our custom design and will share the updated files again for review when they are ready.

RE: issues when flashing a custom board using nrf52833dk debug port P19

Jared — Tue, 29 Nov 2022 08:59:42 GMT

Hi George,

I looked at your design and you really need much more vias both around the ant path and also in the GND layer on the top layer in general. Also, instead of having a power player in the inner layer, you could route the power in the inner layer and fill the remaining layer with GND. We also recommend having a keep-out area on the inner layers directly under the antenna matching circuitry to reduce the stray capacitance.

For example, here is the nRF52833 DK:

regards

Jared

RE: issues when flashing a custom board using nrf52833dk debug port P19

Jared — Mon, 28 Nov 2022 15:33:54 GMT

Hi,

I'll return with a review of your design either tomorrow Tuesday or Wednesday.

regards

Jared

RE: issues when flashing a custom board using nrf52833dk debug port P19

George Shaker — Sat, 26 Nov 2022 19:20:47 GMT

Hello Jared, we are going to replace nRF chipset with new components just to make sure that it is not damaged or does not have any assembly issues.

Also, can you please review the PCB layout and give your inputs/comments on GND via stitching near nRF52833 and review routing/impedance matching of the overall RF path from nRF source till each of the SMA connectors?

Our custom design files are located at http://surl.li/duitk.

Thanks,

Nimesh

RE: issues when flashing a custom board using nrf52833dk debug port P19

George Shaker — Fri, 25 Nov 2022 18:57:19 GMT

For clarity, we removed the J5 connector and probed with coax probe at the conductor signal trace (directly at ANT pin) and we are getting simlar results. See setup and results below:

RE: issues when flashing a custom board using nrf52833dk debug port P19

George Shaker — Fri, 25 Nov 2022 15:07:20 GMT

As mentioned in a previous reply, the J5 connector is in the correct orientation (as specified in the datasheet) to measure the point after the matching network on the ant path when the probe is conencted.

RE: issues when flashing a custom board using nrf52833dk debug port P19

Jared — Fri, 25 Nov 2022 09:53:57 GMT

Hi,

It seems that you're actually measuring something with the radiated test on the custom board. I therefore find it strange that it's such a difference between the conducted measurements when comparing the DK and the custom board. This might be a longshot, but could you try to rotate the J5 connector? I've seen some cases where the connector has been accidently placed the wrong way resulting in similar conducted measurements.

best regards

Jared

RE: issues when flashing a custom board using nrf52833dk debug port P19

George Shaker — Thu, 24 Nov 2022 16:05:39 GMT

We measured the radiated signal using a spectrum analyzer as shown in the setup, and a single antenna tuned for 2.45 GHz (confirmed using VNA).

After a few measurements, the DK was advertising at a power around -47 dBm. See setup and results below. We added a connector to J5, as shown, to disconnect the trace antenna and consider only the radio output. Even with this setup, DK is still beaconing and is visible on the nRF connect mobile application (which shows around -90 dBm).

The custom PCB has a transmit power of around -50 dBm at the BLE advertising channels. See setup and results below; results are similar in terms of signal power on the spectrum analyzer. Note, there is no antenna attached to the custom PCB, this is purely the signal from the radio, not the ant path.

Yesterday, when we measured the power from the ant path, the custom PCB showed a magnitude of around -70dB.

RE: issues when flashing a custom board using nrf52833dk debug port P19

Jared — Thu, 24 Nov 2022 14:48:13 GMT

Hi,

Some of the signal will be radiated directly out from the radio (not through the ant path), can you connect an antenna to the signal analyzer and put it close to the radio, and see if you can measure the radiated signal from the radio?

regards

Jared

RE: issues when flashing a custom board using nrf52833dk debug port P19

George Shaker — Wed, 23 Nov 2022 22:26:25 GMT

[quote userid="73165" url="~/f/nordic-q-a/94115/issues-when-flashing-a-custom-board-using-nrf52833dk-debug-port-p19/397196"]Could you add CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y to the prj.config file? [/quote]

Adding CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y to the config file does not seem to fix the issue. The board is still not beaconing, and is not viewable on the nRF Connect mobile application.

[quote userid="73165" url="~/f/nordic-q-a/94115/issues-when-flashing-a-custom-board-using-nrf52833dk-debug-port-p19/397196"]Have you tuned the device? It might be that the device is advertising, but that it's difficult to see the advertising because the antenna hasn't been tuned. [/quote]

The custom board was flashed and powered up at the DC input at J8 with a 5V-3.3V power adapter. We tested the transmit power at the SWF connector J5 on the board (oriented as shown to measure at the point closest to the nordic chip) to bypass potential issues with antenna tuning. The following results below are seen at the BLE advertising channels. Despite these results, we cannot see the device beaconing on the nRF Connect mobile application.

When measuring the DK at the SWF connector J1, we got the following result below at the BLE advertising channels. After removing the measurement probe, we can also see the DK advertising

[quote userid="73165" url="~/f/nordic-q-a/94115/issues-when-flashing-a-custom-board-using-nrf52833dk-debug-port-p19/397196"]Could you share the full part number and datasheet of your HFXO crystal?[/quote]

To answer your question about the crystal, we are using ECS-320-8-37B-7KM-TR.

Additional details:

- RF matching network for custom PCB and DK after nordic chip are identical.

- Stackup for custom PCB and DK are identical.

RE: issues when flashing a custom board using nrf52833dk debug port P19

Jared — Wed, 23 Nov 2022 14:10:39 GMT

Hi,

EDIT:

I just remembered that you didn't have the LFXO crystal. Have you remembered to configure the nRF52833 to use the internal RC oscillator instead?

Could you add CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y to the prj.config file?

Could you also address my question in my last reply:

[quote user="Jared"]Have you tuned the device? It might be that the device is advertising, but that it's difficult to see the advertising because the antenna hasn't been tuned. [/quote]

Could you share the full part number and datasheet of your HFXO crystal?

regards

jared

RE: issues when flashing a custom board using nrf52833dk debug port P19

George Shaker — Wed, 23 Nov 2022 02:16:28 GMT

Hi Jared,
Thank you for your response. Please see the full schematic and layout: http://surl.li/duitk

Thanks

RE: issues when flashing a custom board using nrf52833dk debug port P19

Jared — Tue, 22 Nov 2022 12:44:20 GMT

Hi,

[quote user=""]Following these results, capacitor C24 in our custom board was removed. No difference in measure Voltage was observed. Custom board is still not functional.[/quote]

I don't understand, why would you remove the decoupling capacitor on VBUS. Can you elaborate?

We always recommend following our reference design, especially in regards to the decoupling capacitors.

[quote user=""]Result: DK does not beacon, setup programs custom board only. Successfully program the custom board with no errors in VSCode when connecting or flashing. However, board is till not beaconing at all.[/quote]

Have you tuned the device? It might be that the device is advertising, but that it's difficult to see the advertising because the antenna hasn't been tuned.

Can you share the full schematic and layout of your custom board?

regards

Jared