NRf52840 custom board does not work when powered by VBUS and not found by J-link

RE: NRf52840 custom board does not work when powered by VBUS and not found by J-link

Kazi Afroza Sultana — Wed, 27 Apr 2022 13:47:59 GMT

Hello,

You can just try to power VDD with 3V while programming instead of VDDH. You should be able to program the device then. With new firmware that you are programming , you can set the REG0 output to 3V. You should be able to flash with the DK later, even when VDDH is powered.

Thanks.

Best Regards,

Kazi Afroza Sultana

RE: NRf52840 custom board does not work when powered by VBUS and not found by J-link

Vahidreza — Sat, 23 Apr 2022 12:38:14 GMT

Hello Kazi

Thanks for your reply

It looks like the problem is what you mentioned, as the voltage on SWDIO pin is less that 1V when connecting the dongle to the DK. The voltage on SWDIO pin is about 2.7V for the other dongles when connecting to the DK.

So I need an external debug probe. But I'm confused which version is good to buy. According to the link you shared I need a programmer that adapts the logic levels to the target device. J-link Pro is offered in there. Does that mean that I can't use a J-Link Base for adapting the logic levels to the target device? I can't afford buying a J-Link Pro now, that's why I'm asking. I tried to find the differences in Segger official website but I couldn't find anything about "Adapting logic levels to the target device".

There are also some other devices with a very low price. They are called Emulators. What about them?

And please tell me if I'm right about the need of external debugger as the voltage on SDWIO pin is less that 1V when connecting to the DK. The voltage on this pin is 2.7V when not connected to the DK but it is not fixed. It sometimes drops down to 1V and sometimes to 0 also. IT IS NOT BEHAVING NORMALLY BY THE WAY.

In conclusion: according to what I explained about the voltage on SWDIO pin, would using an external debugger help? if yes, do I have to buy a J-link Pro or the J-link Base or those cheap Emulators will solve the issue?

RE: NRf52840 custom board does not work when powered by VBUS and not found by J-link

Kazi Afroza Sultana — Wed, 20 Apr 2022 12:16:03 GMT

Hello Vahidreza,

The nRF52840 chip on the dongle hardware is configured in high voltage mode. This uses REG0 to lower the chip supply voltage (VDD) and the default value is 1.8 V, configured by the REGOUT0 register in UICR. This value is too low to be used with the onboard programmer on the nRF52840 DK, so erasing or programming with a firmware that does not configure the regulator for a higher VDD will leave it in a state where it can not be reprogrammed from a DK.

I think that's why you are having these issues. You can check this dongle programing tutorial (+) nRF52840 Dongle Programming Tutorial - Getting Started - nRF5 SDK guides - Nordic DevZone (nordicsemi.com) to have the idea.

Thanks.

Best Regards,

Kazi Afroza Sultana

RE: NRf52840 custom board does not work when powered by VBUS and not found by J-link

Vahidreza — Tue, 19 Apr 2022 05:35:53 GMT

DCDC is disabled and there is no configuration for the VDD voltage. So the values are as defaults.

I wish I knew what exactly happens after that pulse? Why the pulse is needed? I thought the internal regulator is damaged, but if it is that way, how does it work after the pulse?

As I mentioned, I'm not able to program the dongles as no J-Link can find them. What should I do about that?

Can the voltage cause the issue? if YES so how the other dongles are working without a problem?

RE: NRf52840 custom board does not work when powered by VBUS and not found by J-link

mytzyiay — Mon, 18 Apr 2022 18:21:24 GMT

Not sure, but I would check:

If you're using high voltage mode and you don't have the LC circuit on DCCH, make sure the regulator (DCDCEN0) is configured to use LDO mode rather than DC/DC mode
In high voltage mode, VDDH needs to be at least 0.3V higher than VDD. What voltage is your VDD configured for, anyway? It looks like that voltage is not correct even after applying the pulse?
Some more hints in https://devzone.nordicsemi.com/f/nordic-q-a/76855/nrf52840-high-voltage-mode-specs

RE: NRf52840 custom board does not work when powered by VBUS and not found by J-link

Vahidreza — Mon, 18 Apr 2022 05:55:57 GMT

Thanks for your reply

I did not make any change on UICR in my code personally. But the company sent me HEX file which can erase the whole chip by itself when you program the chip by that. I did that. And I thing what that I did wrong was that I didn't give the chip enough time to be erased completely and interrupted it by removing the power.

In my circuit VBUS and VDDH are short-circuited so that here it looks like that the problem is that the dongle does not work in High Voltage mode until it is powered up in low voltage mode. VDD and DCCH are short-circuited as well and the voltage measured on these pins on one of the malfunctioning boards are as below:

when putting 2.94V on VDDH the voltage on VDD (and DCCH) is 0.44V and when I give a very short pulse of 2.98V to VDD, the voltage on this pin is remained on 2.7V and the dongle works.
when putting 5v on VDDH the voltage on VDD (and DCCH) is 0.45V and by giving a pulse as explained above the dongle starts working.
when putting 2.98V on DVV the voltage on VDDH is 2.71V and the dongle works.

In one of the good boards that I measured, when putting 2.97V on VDDH the voltage on VDD is 2.94V and the dongle works without the need of that pulse.

RE: NRf52840 custom board does not work when powered by VBUS and not found by J-link

mytzyiay — Sun, 17 Apr 2022 16:59:31 GMT

Are you using Normal Voltage mode or High Voltage mode? Did you erase UICR during programming? https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52840%2Fpower.html

In order to better assess what the chip is doing, it might be helpful to measure + post the voltages on VDD, VDDH, DCCH, VBUS from 1) the good boards; and 2) the malfunctioning boards