nRF52833-QDAA-B SoC chipset not detected during testing

[Jhakan]

Hello team,
We are currently working on a project that used nRF52833-QDAA-B as the MCU chipset. We have  followed the circuit configuration 5 for our test case. Our SoC is not getting detected when we have used this configuration. Whereas, when tried the same with nRF52833-QDAA-R/ nRF52833-QDAA-R7( same number of pins, package)  the chipset is being detected and we are able to build & flash the code. Kindly specify why this occurs and how to rectify this.

Also specify is we can work with  nRF52833-QDAA-R and build our entire project. If not what are the complications if used.

[Simonr]

Hi

Can you explain what you mean by "not getting detected" exactly? The QDAA-B chipsets have readback protection enabled by default, so it might be this that's making you not be able to detect the board. Try running an nrfjprog --recover command to recover and recover the board where the readback protection is disabled.

Best regards,

Simon

[Jhakan]

Hi Simon,
We use a JTag device to flash the SoC. When we tried with nRF52833-QDAA we were able to flash properly. But wheras in the case of nRF52833-QDAA-B the Soc was not visible under the connected devices drop down in Visual studio. Hence we weren't able to flash or debug with this chipset 

[Gaurav Kapoor]

Simon is it because of the design variation required for -B , Document AN149 , C8 capacitor thing ?

[Simonr]

Hi

Thanks for the pointer Gaurav. Can you specify in this ticket what exactly is printed on the SoC that doesn't work correctly. N52833 should be the top line, but what are the other three? I think this SoC should be newer, and not require the C8 capacitor, but for clarity, do you have this capacitor included in your HW design Jhakan?

Best regards,

Simon

[Jhakan]

Hello Simon,
Based on my understanding the only difference in hardware Configuration between nRF52833-QDAA & nRF52833-QDAA-B seems to be the C8 820 pF capacitor not to be installed. In our HW design we have a pad allocated for this capacitor however we haven't placed it in our pcb board.

In addition to this, we also observed some other things that we wanted to clarify with you guys. Currently we have started working with nRF52833-QDAA  and flashed firmware build over JTag. The voltage input for the chipset and the other components installed is 1.8 V and it is constantly provided using a LDO . The Jtag used has voltage of 3.3 V and for debugging UART we use FTDI that also supplies 3.3 V. When debugging using FTDI our device undergoes continuous reset and the BLE advertising also stops. We want to know if this is because of the voltage difference between our board input voltage and the UART debugger.