Issue programming custom nRF5340 board with nRF7002 development kit

[shay_siah]

Hello,

I am attempting to program a custom nRF5340-based board using the nRF7002 development kit, but the device won’t be recognized by nrfjprog, and the programming operation fails.

I followed the kit’s user guide to connect the custom board: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrf7002_dk%2FUG%2Fnrf7002_DK%2Fext_programming_support_P20.html

The custom board is based on the reference circuit configuration 1 with the external 32.678 kHz Crystal installed: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf5340%2Fchapters%2Fref_circuitry.html&cp=4_0_0_8_2

I also tried connecting VDD_HV on the custom board to VBAT (P20) and VTG (P20) on the kit, but still had the same issue. Is what I am attempting possible, or is this most likely to be an issue with the custom board?

Thank you,

Shayan

[Elfving]

Hello Shayan,

The nRF7002-DK also requires the external board to be 1.8V powered. Is that the case for your custom board as well? This would for instance make it hard to program the nRF5340DK using the nRF7002DK, since they have different power levels. It is typically either the voltage or the connections that are at fault.

You do not have any issues programming the main SoC on the nRF7002DK itself I assume?

Regards,

Elfving

[shay_siah]

Hello Elfving,

You are correct, there are no issues programming the main SoC on the nRF7002DK itself. The SoC on the external board is supplied by the VDDH pin, which can accept 2.5-5.5V. But I believe the GPIO pins operate at 1.8V because this is the voltage of VDD. To provide more context, the external board is using an nRF5340 SoC in high voltage mode with the nRF7002 Wi-Fi IC connected to it - the high level schematic is close to this one pulled from Nordic documentation:

 

So if VDDH on the external board is supplied with 3.6V from the VBAT pin on P20, would the NRF7002DK will be able to program the external board?

Thank you,

Shayan

[Elfving]

Hello Shayan, and sorry about the wait. 

Unless you've made changes in the VREGH register, then yeah I guess you should still be able to program the custom board like this. 

What is important is that the ground and voltage level (VDD) must be the same on the DK (used as programmer) and the target board (with the SoC to be programmed). For the nRF7002DK that is 1.8V. 

Can you make sure that the board is getting power? 

I'll have to get back to you on this next week.

Regards,

Elfving

[shay_siah]

Hello Elfving,

I can confirm that no changes have been made in the VREGH register, and that VDD measures 1.8V when powered by the DK (used as programmer).

At this point, I am fairly certain that the issue is a bad connection between the SoC and the PCB. What method would you recommend for checking the solder connection of the 5340? We are using an aQFN package for the first time, and could use some guidance on working with it.

Thank you,

Shayan

[Elfving]

shay_siah said:

At this point, I am fairly certain that the issue is a bad connection between the SoC and the PCB.

Yeah if the voltage is fine, then that might be. You could also try another programmer such as a JLink Commander, though those can be a bit pricey.

If you are uncertain about the soldering you can do a reflow. Here is a whitepaper describing how to do it with a QFN.

Regards,

Elfving