RTC and sleep mode

[Daniel]

Hi everyone,

I am developing a quick evaluation demo for a low-power sensor node which consists of the following steps:

- read a couple of GPIOs

- set advertising name based on their status and advertise for X amount of seconds

- Once advertising is done, setup RTC/ other timer to generate an interrupt after Y time

- Go to lowest sleep state while keeping the timer on

- Wake up and start the process again

Does anyone know how to do the last three steps? Note that this module may be put to sleep for weeks for the application.

I am using the S140 device.

Thank you all

[Daniel]

Hi, to answer your questions:

I am using the dongle. I am measuring current between a battery and the nRF supply. I have changed the USB jumpers to do this. No other hardware connected.

I do not think I am disabling any RAM. Not sure on how to do this. How can I check my LFCLK. 

My code is all up there ^^

Thanks

[ovrebekk]

Hi Daniel

Do you also have an nRF52840 DK to test on, or do you only have the dongle?

Most likely the dongle is less power optimized, but I would have to do some digging internally. 

By default all the RAM is on in system ON idle mode, so most likely you are not disabling anything. 

RAM can be disabled by using the sd_power_ram_power_set(..) function, as documented here and in chapter 5.3.7.22 on page 79 of the nRF52840_PS_v1.1

According to the comments in your code internal LF clock is used, which is fine power wise. 

Best regards
Torbjørn

[Daniel]

Hi there,

I am working on disabling the RAM and have found the following:

for (int i = 0; i < 8; i++) {
sd_power_ram_power_set(i,
(POWER_RAM_POWER_S0POWER_Off << POWER_RAM_POWER_S0POWER_Pos)
| (POWER_RAM_POWER_S1POWER_Off << POWER_RAM_POWER_S1POWER_Pos)
| (POWER_RAM_POWER_S0RETENTION_Off << POWER_RAM_POWER_S0RETENTION_Pos)
| (POWER_RAM_POWER_S1RETENTION_Off << POWER_RAM_POWER_S1RETENTION_Pos));
}

However, I tried this and see no difference when it comes to the power consumption. Still around 5.5uA.

Am I doing something wrong?

[ovrebekk]

Hi Daniel

Do you have an nRF52840 DK you can test on for reference?

If not, can you send me the code so I can test it on my end?

Best regards
Torbjørn