NRF52811 help regarding power saving/sleep mode

RE: NRF52811 help regarding power saving/sleep mode

Sigurd — Thu, 17 Dec 2020 21:22:50 GMT

[quote user="zazas321"]I guess that would mean that the System OFF mode is not possible here?[/quote]

Correct.

[quote user="zazas321"]The most viable choice would be System ON working in low power sub system mode? [/quote]

Correct.

[quote user="zazas321"]I would see the device appearing and dissapearing or 5 seconds? [/quote]

Correct.

[quote user="zazas321"]If so, how will I be able to reliably connect to it?[/quote]

You will be able to connect to it, but it will take longer time to discover and connect to it, since it only advertises every 5 seconds. It's a trade-off .You can easily test this yourself, take for example the ble_app_blinky example in the nRF5 SDK, set the advertising interval to 5 seconds, and try connecting to it using your phone with the nRF Connect for mobile app.

RE: NRF52811 help regarding power saving/sleep mode

zazas321 — Thu, 17 Dec 2020 05:52:56 GMT

Thanks a lot for the response. That was very helpful understanding more about the funcionality of your device. Also, I would like to ask one more question if possible:

1. For my application, I have mentioned that I need to be able to connect to the bluetooth at any time and also monitor some other sensors. I guess that would mean that the System OFF mode is not possible here? The most viable choice would be System ON working in low power sub system mode?

Also, could you explain me a little bit about long advertising. If I select long adveretising such as 5 seconds intervals, would that mean that if I check on my mobile phone nearby bluetooth devices, I would see the device appearing and dissapearing or 5 seconds? If so, how will I be able to reliably connect to it? Im not fully understanding it yet.

Thanks in advance

RE: NRF52811 help regarding power saving/sleep mode

Sigurd — Wed, 16 Dec 2020 20:02:31 GMT

Hi,

[quote user=""]The GSM module uses USART to talk between CPU and the GSM module.[/quote]

When you say CPU, I assume you mean the nRF52 device ?

Also, if you are looking for a low-power LTE-M/NB-IoT modem, then I recommend checking out our nRF9160.

[quote user=""]Since the BLE chip has one USART port available, I believe that should not be a problem right?[/quote]

Correct, that should not be an issue. The nRF52811 has 1 UART(E). If you need more, then you can upgrade to the nRF52833 or the nRF52840, that have 2 UART(E).

[quote user=""]The usart is probably used to flash the device but I can connect some external USART device to it?[/quote]

With a debugger(e.g. Segger Jlink) you can flash the device using the SWD interface. If you need to do a DFU(device firmware update), then our SDK provides you with a bootloader that supports multiple transport layers, e.g. Bluetooth or serial(UART, or USB CDC ACM if you select a nRF5 device with built-in USB). And yes, you can connect the UART(E) to an external device/UART.

You can read about the different system power modes at this link.

[quote user=""]I am slightly concerned whether when in power saving mode, any of the peripherals will be enabled such as SPI / I2C? [/quote]

In System OFF mode, they will be disabled (since the system’s core functionality is powered down in this mode).In System ON mode, you turn these serial peripherals ON or OFF as you want.

It's a ultra low-power radio, depending on how your configuration is, you can do connectable adverting and still get average power consumption well below 10µA. With a long advertising interval, and low tx power configuration, you can even get it down to ~3 µA. Please have a look at our Online Power Profiler for BLE at this link.