debugging while using external supply on NRF52840-DK

RE: debugging while using external supply on NRF52840-DK

Stian Røed Hafskjold — Wed, 29 Jun 2022 14:33:03 GMT

Hi Hossein,

I found a solution which might work for you. You can use the REG0 on the nRF52840 to output 3.3V. There is a voltage follower on the DK VDD that follows the nRF52 VDD when using high voltage mode. So by setting REGOUT0 to 3.3V, the VDD on the DK will also be 3.3V, and you can still use J2 for debugging.

Write 5 to the REGOUT0 register
- nrfjprog --memwr 0x10001304 --val 5
- power cycle
Plug in a USB cable to J3. (using two cables, both for J2 and J3)
Set nRF power source switch to USB
Check that the VDD voltage is now 3.3V
Leave the other switches in their default position
- SW10 to OFF
- SW6 to default
- Do not supply power to the external supply header
- Make sure that SB40 and SB41 are not cut, or put a header on P22 and P23

So what happens is that the nRF52 is powered from J3 at VDDH using the nRF power source switch. Then it outputs 3.3V to nRF_VDD. The VDD on the DK follows the voltage on nRF_VDD, so that the IO voltage is the same as on the nRF52 chip. The debugger is still powered from J2.

Also maybe check that your software is not overwriting REGOUT0. Remember that in order to change the value on REGOUT0. UICR will have to be erased first, since it's part of the flash (nrfjprog --eraseuicr).

Best regards,
Stian

RE: debugging while using external supply on NRF52840-DK

hossein_m — Mon, 20 Jun 2022 11:47:56 GMT

Hi Swathy,

Sorry for the late response.
- A photo of my setup:

- I use the J2 USB port to debug my project and connect the external power source to P21.

- To test whether the board works with an external supply, I wrote a simple code to toggle one of the pins on the board ( one that has no connection with any peripherals on the board). This code worked fine when SW10 was off but didn't work when it was on.

If there are any other switches or options related to this problem, please let me know to check them too so we can reach a solution.

Bests,

Hossein

RE: debugging while using external supply on NRF52840-DK

SwRa — Wed, 15 Jun 2022 13:27:12 GMT

Hi Hossein,

The device should not stop working when SW10 is ON.. Could you tell me how you made the connections ? Did you connect the external power supply to P21 or P22.? Take a look at the set up mentioned here: https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/dk/direct_supply.html?cp=4_0_4_7_2_4

Also, which USB port did you use to connect the USB (J2 or J3).? It would be better if you could share a photo of your set up..

Regards,

Swathy

RE: debugging while using external supply on NRF52840-DK

hossein_m — Mon, 13 Jun 2022 13:11:13 GMT

Hi,
The SW9 is on VDD. I mentioned in my first message that I didn't change any switch/jumper on the DK, and everything is on default mode.

Based on the DK's user guide I guess it should be solved using SW10, but I don't know why NRF stops working when SW10 is ON.

Bests,

Hossein

RE: debugging while using external supply on NRF52840-DK

SwRa — Mon, 13 Jun 2022 10:55:30 GMT

Hi Hussein,

In that case, you will see a switch for nRF power source on the DK

There are 3 options.. Li-Po, Vdd and theUSB.. Could you make sure that it is not set to USB?

Regards,

Swathy

RE: debugging while using external supply on NRF52-DK

hossein_m — Thu, 09 Jun 2022 13:54:35 GMT

Hi,
I am using the NRF52840-DK ( pca10056). I will change the title; sorry for the confusion.

I am using the MAX3421e USB host shield, although I've modified it to work in only 3.3v. The pins are based on Arduino Uno, and the shield worked fine with the Arduino board.

https://5.imimg.com/data5/XK/RR/MY-1833510/usb-host-shield-for-arduino.pdf

https://github.com/felis/USB_Host_Shield_2.0

Also, I tried to use the SW10 to only use the external supply for the NRF, but even though there is a voltage on NRF52840's supply pins, it doesn't turn on. Do I have to make any more changes to the board?

Bests,

Hossein

RE: debugging while using external supply on NRF52-DK

SwRa — Thu, 09 Jun 2022 10:58:53 GMT

Hi Hossein,

Are you using the nrf52 DK or the nrf52840DK.? The tag you added confused me a bit.. Also, could you provide the link to the Arduino shield that you are using just to double check the pins..?

Regards,

Swathy