i2c_nrfx_twim power management in NCS 2.7.0

RE: i2c_nrfx_twim power management in NCS 2.7.0

Hung Bui — Fri, 28 Feb 2025 13:25:29 GMT

Hi,
The 110uW (30uA ?) is in System on or System OFF ? The current consumption in System ON depends on the peripheral and the activity. But I doubt that accessing the registers directly (nrfx) can save a few uA.
My suggestion is to use a PPK2 to check the actual idle current.

RE: i2c_nrfx_twim power management in NCS 2.7.0

Anthony Ambuehl — Thu, 27 Feb 2025 23:00:37 GMT

I tried PM_DEVICE_RUNTIME but it caused gpio-keys to break. I think it was disabling the gpiote module during sleep. For now I have replaced pm_device_runtime_get/put calls with nrfx_twim_enable/disable and appear to save around ~2uW of power.

Our standby power is currently around 110 uW which is acceptable but I'm always looking for ways to shave a bit more off.

RE: i2c_nrfx_twim power management in NCS 2.7.0

Hung Bui — Thu, 27 Feb 2025 12:43:49 GMT

Hi Anthony,

My understanding is that what depreciated is the PM module not PM_DEVICE.
You can find CONFIG_PM_DEVICE is still used in our nrf samples in NCS v2.9 (for example in \zephyr\samples\boards\nordic\system_off sample) and pm_device_* is used there.

Could you tell what's the current consumption you have when you enter System ON idle and System OFF in your test (with pm_device APIs) ?