nRF52833 development

[deknoob]

Hello all,

I am working on low power sensor development with nRF52833 as target. I have some questions but I'm not sure it this was addressed in some other posts.

1. I don't have nRF52833 DK but instead I use nRF52840DK for development under SES environment. What in particular should I be aware of when generating target code for nRF52833?

2. I wan't to place sensor in sleep state for longer period of time. From product spec I understand that I should use wake on RTC and no RAM retention for lowest possible power. Because of no RAM retention, I need CPU to restart after timeout, not to go to application timer timeout handler but to top of main. How can I set this up?

Thanks

[Simonr]

Hi

I'm sorry, but setting the rtc_handler to 0 in the nrf_drv_rtc_init() bricks the device on my end. Have you made any other changes to your application to allow for this setting to 0? What current consumption is the best you're able to achieve? I've tested myself on an nRF52832 DK (the only DK I had at hand this morning, which according to the spec. should draw ~1.9µA in this mode) and got it down to ~2.3µA with very small adjustments to the RTC handler.

As for the 1.5µA that is stated in the spec. this is the absolute lowest possible current consumption you can achieve with the RTC running. This is a combination that's not really usable in and of itself as you will always need to have some RAM enabled if you'd want to execute interrupts, etc. The SDK examples are made to be generic and suit most use cases, and are likely in need of modifications in order to suit specific use cases. With the RTC module in the SDK with a usable application wrapped around it, getting the current consumption down to ~2.0µA should be feasible during sleep mode, depending on the application of course.

My apologies for any confusion and misunderstandings throughout this thread.

Best regards,

Simon

[deknoob]

Hi Simon,

I did not make any other changes to the app I included in last post, Just setting RTC callback to zero. 

I am using nrf52840 DK for development and my application is drawing 2.8uA @3V while sleeping. There is absolutely no activity happening during sleep, except maybe for RTC ticks. I am quite happy with this, but trying to improve as much as I can because this product will have soldered battery which should last for 10 years. I will eventually disable some RAM and my target device is nRF52833 which has only half of RAM compared to 52840, so I will be able to reduce consumption. 
Thank you for your support

[deknoob]

My application is using around 32KB of RAM. Hence I should be able to turn off power to some RAM sections. How can I find out which RAM sections I am able to power off in system ON mode, without application crashing?