ESB power consumption

Question

Hi,

I am developing a sensor that uses the ESB protocol. "System On mode", sleeps most of the time. Problem is, that the PTX device uses 430uA current all the time while sleeping (measured with PPK2). I've tried with the ESB example, my own code (started from "System_Off" example),disabled all peripherials one by one, but current is still more than 420uA. With some other examples (not ESB), sleeping in System On state is 2.6uA, System Off state is 0.9uA. I have tested with my custom board with nRF52840, nRF52840DK, nRF52840 dongle, same result. I'm using VSC, tried nRFConnect versions 2.2.0, 2.3.0, 2.4.0, 2.4.1. Same result.

Added to sample:

#include <zephyr/pm/pm.h>

#include <zephyr/pm/device.h>

#include <zephyr/pm/policy.h>

and

CONFIG_PM=y

CONFIG_PM_DEVICE=y

disabled all peripherials one by one, tested every time.

Br,
Urmas

Einar Thorsrud · Answer

Hi Urmas, 
 The ESB PTX sample starts the HF crystal clock (HFXO) at the start of the application (in clocks_start()), and let it run forever. This causes a high idle current consumption. To reduce this, you can modify your application so that you start the HFXO (and wait for it to start) to before you want to send anything. Then, in the event handler you can call esb_is_idle(), and stop the HFXO if it is idle. 
 Einar