Preprogramming nRF54Lxx with socket

[WoutWG]

Hi,

We're trying to preprogram our nRF54L05 SoCs before SMT as this is more efficient in our production process. In the past, we did this successfully with an nRF52810, but now it seems that we're running into issues:

When we enable logs during programming, we get advice to check the power lines.

For the moment, the setup is just a socket wherein the SoC is placed and the relevant pins of the socket connected to a JTAG cable, which is connected to the programmer. This worked with the nRF52810, but I'm wondering if we need more peripheral components for this to work with the nRF54Lxx? Do we need, for example, the capacitors on pins 33 and 45 (DECA and DECD)? Or should it just be possible to program the SoC when it's mounted in just a socket with the correct connections made?

Best,

Wout

[Håkon Alseth]

Hi,

For the moment, the setup is just a socket wherein the SoC is placed and the relevant pins of the socket connected to a JTAG cable, which is connected to the programmer. This worked with the nRF52810, but I'm wondering if we need more peripheral components for this to work with the nRF54Lxx? Do we need, for example, the capacitors on pins 33 and 45 (DECA and DECD)? Or should it just be possible to program the SoC when it's mounted in just a socket with the correct connections made?

We do not test our devices without any external components, so answering your question here is quite hard, as the recommendation is to always have the minimum recommended setup wrt. the decoupling caps that we recommend:

https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/chapters/ref_circuitry.html

 

What type of programmer are you using specifically?

Are you able to successfully identify and program, lets say an external nRF54L-series DK, with this programmer setup?

 

Kind regards,

Håkon

[WoutWG]

Hi Håkon,

Thank you for the feedback. We eventually were able to program the SoC in the socket, but we had to do some workaround to get everything powered correctly.

From this thread, we knew that powering the SoC without any peripherals would fall back on the LDO operation. But Fig 1 of the power regulators indicates that the LDO only powers DECA, so we shorted DECA with DECRF and DECD on our socket, which got it working. I don't know if this is very stable, so I probably don't recommend this for production without the caps (which may help stabilize), but still documenting our experience in case someone else is in this situation.

Just for completeness, currently we're using an nRF54L15DK as programmer (through the Debug Out connector), making sure that we don't program the nRF54L15 that's on there. But we're also using a Jlink Base unit.

Best,

Wout

[Håkon Alseth]

Hi Wout,

 

I am glad to hear that you got it working.

As you also mentionl; I would recommend that you mount the minimum required circuitry, even on a socket board, to ensure stable operation while programming the chip placed in the socket.

You can ofcourse omit the radio-part and the xtal(s).

 

Kind regards,

Håkon