Power Optimization

RE: Power Optimization

Edvin — Mon, 13 May 2024 11:35:50 GMT

Sorry. I don't think we have any use cases for our current chips. I believe it is more suited for larger chips that have different power domains that needs to be handled in order to turn on certain peripherals, but that is not something we currently have.

It will probably (but I am not sure) be more useful in the upcoming nRF54 series.

Best regards,

Edvin

RE: Power Optimization

ATla5 — Mon, 13 May 2024 08:29:02 GMT

Hello,

Sry for my late reply. No, what I mean are power domains. Note, that the links provided by Zephyr are not working and the sample folder does not contain any examples. That is why I wanted to know if you can share a use case, where power domains are applicable.

If not, then we can close this ticket.

RE: Power Optimization

Edvin — Mon, 29 Apr 2024 11:52:51 GMT

Hello ATla5,

[quote user="ATla5"]

What do you think causes the approximately 4µA difference between measuring with the

[/quote]

Without being able to say exactly where, I believe what you are seeing is that some parts of the DK (such as the debugger) is being backpowered from the nRF when the DK is not powered separately. It will not be operational, but you will see some leak current, possibly through the UART pins.

[quote user=""]

As far a I am aware, Zephyr uses the low frequency clock automatically when it is in a low power mode. Can you confirm this?

[/quote]

Yes. It uses the LFCLK for timekeeping when it is sleeping.

[quote user=""]

May you explain why the I2C-Twim driver uses PM_DEVICE_RUNTIME feature and the UART does not (PM_DEVICE)?
When implementing a driver when should someone use the runtime version of the power mangement feauture? Does it depend on device usage or any hardware restriction?

[/quote]

I don't know this. Perhaps because UART is the default backend for all printk() and logging (log module, such as LOG_INF()), which is why it is set up differently.

[quote user=""]Can you share a sample or a scenario (block diagram) where an application should make use of the power domain feature of Zephyr? Since the Thingy:53 offers additional peripheral circuits may you share how to make use of this feature with that hardware and why.[/quote]

I am not sure I understand this question. Are you asking when you should power down peripherals? It depends. Some peripherals draw more current than others. The UART is an example of a peripheral that draws more power, because it will keep the HFCLK running (because you don't know when the other device will transmit something, so it needs to be ready (it's asynchronous). This is not the case with most other serial protocols, such as SPI. In this case, the slave can wake on the CS pin, and the master will be in control of the events, so it doesn't need to keep the HFCLK when not in use.

Best regards,

Edvin

RE: Power Optimization

ATla5 — Fri, 26 Apr 2024 08:47:52 GMT

Hello Edvin,

I have performed the following measurements again

1. Measurement #01

nRF52840-DK
- SW6: DEFAULT
- J2 USB power supply
PPK2
- Ampere meter mode
SW
- suspends SPI and UART-0 (other peripherals disabled) and calls k_sleep(K_FOREVER)
Results:
- average current consumption is 3.52µA

2. Measurement #02

nRF52840-DK
- SW6: nRF_ONLY
- J2 USB power supply
PPK2
- Ampere meter mode
SW
- suspends SPI and UART-0 (other peripherals disabled) and calls k_sleep(K_FOREVER)
Results:
- average current consumption is 3.54 µA

What do you think causes the approximately 4µA difference between measuring with the

PPK2 (measured at P22)
N6705B (measured at P21)

Also, do you have an answer for points 4 to 6 of the original question?

Best regards,

ATla5

RE: Power Optimization

Edvin — Thu, 25 Apr 2024 13:00:17 GMT

I see that you edited the ticket after my reply, but I don't have access to a changelog. I'll await your reply before looking into this.

BR,

Edvin

RE: Power Optimization

Edvin — Thu, 25 Apr 2024 09:11:13 GMT

Hello Atla5,

Can you please try to power the DK like you would normally do (via the micro-USB port on J2), put the nRF_ONLY back to Default, and then try to measure the current on P22? Does the current consumption go down if you do that?

Best regards,

Edvin