Android connect to 51822 issue when in low advertising

RE: Android connect to 51822 issue when in low advertising

kfcube — Tue, 07 Apr 2020 13:25:06 GMT

Got it. thanks.

RE: Android connect to 51822 issue when in low advertising

ovrebekk — Tue, 07 Apr 2020 08:30:40 GMT

Did you also test this with a development kit?
If the current consumption is higher with the nRF52810 it points to an issue with the hardware design or the software configuration.

Regarding powerdown examples for the nRF51, one of my colleagues in support made such an example several years back, and you can find it on our Github account:
https://github.com/NordicPlayground/nrf51-powerdown-examples

It has separate examples for system OFF and system ON, with either GPIO or RTC wakeup.

Best regards
Torbjørn

RE: Android connect to 51822 issue when in low advertising

kfcube — Sat, 04 Apr 2020 00:42:50 GMT

Torbjørn, thanks for those information - very helpful! Actually I do have board with 52810 but unfortunately it has much higher current consumption than 51822. I used SDK16 and s112 for 52810.The mems is lis3dh. All code logic are the same. The schematic is exactly followed the spec. The current with different chips in our case are attached below (unit is MA). We use CR2032 battery. I am still trying to figure out how to deduce the current of 52810 board anyway but at this moment we have to stay with nRF 51 to meet the product timeline.

For the interrupt pin to wake up nRF device, can you please share more details about that part, such as how to do, what the code look like, or any sample references? The mems is lis3dh.

RE: Android connect to 51822 issue when in low advertising

ovrebekk — Wed, 01 Apr 2020 11:27:15 GMT

With an advertising interval as high as 10 seconds I think this is to be expected. Connection time will be very slow, and if you are developing an app on the phone side you would have to set it to retry connecting to your device until it succeeds.

Do you have a target for how low the average current should be in advertise mode, based on your expected battery life time and the size of your battery?

If low current consumption is a requirement I would strongly recommend switching to an nRF52 series part rather than the nRF51822. Typically you are looking at down to 50% of the current consumption when running Bluetooth (not to mention the improved performance, feature set and more of the nRF52 devices). Is there any particular reason you are sticking to the nRF51 series?

1. The connection interval makes no difference in advertise mode. These settings are only relevant once a connection is established, but once you do this they will impact current consumption. The only reason to use a small connection interval is if you need to transmit a lot of data, or if you need low latency.

2. No. Unless the nRF device advertises there is no way for the phone to connect to it.

3. I don't know what capabilities your mems sensor has, but if it has an interrupt pin of sorts you might be able to configure this to wakeup the nRF device when some data is acquired. The nRF device can go into a lower sleep mode when waiting for pin wakeup than when running a timer.

For the nRF52 series we have an online power profile that allows you to check the average current consumption in various advertising and connected states. This allows you to calculate which intervals you should use to get below a certain current consumption target. We don't have a similar one for the nRF51822 unfortunately, but as mentioned it will be up to twice as high depending on configuration and supply voltage:
https://devzone.nordicsemi.com/nordic/power/

Best regards
Torbjørn