nRF52840 application won't completely run without power applied to VBUS

RE: nRF52840 application won't completely run without power applied to VBUS

Dan Halbert — Wed, 02 Mar 2022 14:19:30 GMT

amaul, did you ever figure out a fix for this? It appears someone else may be having the same problem.

https://devzone.nordicsemi.com/f/nordic-q-a/83266/spim3-not-work-standalone

Sigurd, see that as well. This seems like some kind of peripheral hw issue. Has Nordic looked at this further?

RE: nRF52840 application won't completely run without power applied to VBUS

Dan Halbert — Sat, 04 Sep 2021 19:31:16 GMT

Are you using SPIM3? We are seeing what appears to be the same problem in CircuitPython, which allocates SPIM3 first. On USB power it works; on battery power there is no SPI clock present. See github.com/.../5233.

RE: nRF52840 application won't completely run without power applied to VBUS

amaul — Mon, 24 May 2021 16:16:49 GMT

Unfortunately no, working through the firmware still.

RE: nRF52840 application won't completely run without power applied to VBUS

Sigurd — Fri, 21 May 2021 10:28:23 GMT

[quote userid="104055" url="~/f/nordic-q-a/74754/nrf52840-application-won-t-completely-run-without-power-applied-to-vbus/309081#309081"]I'll need to check with the BSP on APP_USBD_EVT_POWER_READY or APP_USBD_EVT_POWER_DETECTED. I don't specifically call those.[/quote]

Did you make any progress on this?

Is the issue resolved?

RE: nRF52840 application won't completely run without power applied to VBUS

amaul — Mon, 10 May 2021 20:24:19 GMT

SPI signals are obviously coming through with VBUS powered. With VBUS disconnected the only signal that I have a heartbeat on is Chip Select. MISO, MOSI and CLK are low and do not even trip a trigger acquisition. Signal frequency doesn't really match the working configuration, but I supposed that would be expected. Logic level and voltage level looks correct. I'll need to check with the BSP on APP_USBD_EVT_POWER_READY or APP_USBD_EVT_POWER_DETECTED. I don't specifically call those.

RE: nRF52840 application won't completely run without power applied to VBUS

Sigurd — Mon, 10 May 2021 17:51:53 GMT

[quote user="amaul"] I need to probe the lines to confirm, but I presume that would tell me there is an issue in the software, correct?[/quote]

Yes, most likely, i.e. SPI commands are not sent/received, but it could also indicate HW issues if there is a change in voltage level used for "logical 1"/"high level". You might want to check you firmware code as well, to see that you are not waiting for USBD events like APP_USBD_EVT_POWER_READY or APP_USBD_EVT_POWER_DETECTED before starting the display.

RE: nRF52840 application won't completely run without power applied to VBUS

amaul — Mon, 10 May 2021 15:11:11 GMT

Yeah that's where I'm at. I have confirmed 3.3V using our onboard and external power supply.

Yes, the display is controller over SPI. I need to probe the lines to confirm, but I presume that would tell me there is an issue in the software, correct? I have placed a delay in the code to reset the display driver well after the nordic chip boots but that did not fix the issue.

RE: nRF52840 application won't completely run without power applied to VBUS

Sigurd — Mon, 10 May 2021 14:55:28 GMT

[quote user="amaul"]Both are powered by the same 3.3V supply,[/quote]

Ok, so VBUS should not affect this ? Have you checked that it's 3.3V when VBUS is both connected and not connected?

You control the display from the nRF52840 using SPI? Have you probed the lines, and checked if there is any difference when VBUS is both connected and not connected? e.g. what data is sent over SPI, and the voltage on the SPI lines

RE: nRF52840 application won't completely run without power applied to VBUS

amaul — Mon, 10 May 2021 13:46:29 GMT

Thanks for getting back to me. Below should be the requested information. For the most part the design is straight out of reference designs.

Display Driver Circuit:

Microcontroller:

Both are powered by the same 3.3V supply, the micro having power through a ferrite bead. No sequencing of power.

RE: nRF52840 application won't completely run without power applied to VBUS

Sigurd — Thu, 06 May 2021 16:49:14 GMT

Hi,

[quote user=""]Our first circuit configuration was this, which matched one of the modes (or so we thought)[/quote]

Yes, this seems to be similar to reference circuitry configuration no. 3 : https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52840%2Fref_circuitry.html&anchor=unique_655538765

[quote user=""]Our application uses an external display driver with touch screen controller to interact with the user.[/quote]

Could you upload the schematic that shows how this display driver/touch screen is powered, and connected to the nRF52840?