Does nrf51822 have a clock?

[benevbright]

Hi,

I wonder if nrf51822 has a clock inside it. It doesn't need to be real clock

but It's important to me. I store datas on flash and send it to the phone when it's ready to send.

But there is no guarantee that device is alive. so I store its time together when they are stored. so that I could send it with time difference from now.

but I have to need a clock for the case that battery is gone.

So is there a clock like?

[Michael Dietz]

The nRF51 has an internal 16 MHz RC oscillator.

However, if you want to use the RADIO peripheral (you want to use BLE or ANT etc...) then you MUST include an external high frequency clock (see nordic's reference designs).

Also an external low frequency 32.768 kHz crystal is optional (reduces current when using BLE and other timers) but the interal RC oscillator can generate this signal. See this post: devzone.nordicsemi.com/.../

But if you are talking about a real time clock - a clock that stores the time in hours and minutes (i.e. 12:48) then you will need to implement this yourself using the TIMER peripheral.

-Mike

[benevbright]

@Michael. Thanks for your help. but as you said little, there is no guarantee that device sends something to phone before it turns off. The phone could be at the outside or could be not connected with device. So I need to make device to figure out itself.