# Accurate clock synchronisation using bluetooth low energy

Is it possible to get accurate clock synchronisation between two arduino 101 boards using bluetooth low energy?

Which clocks are you talking of? I don't know the 101 boards personally but the description doesn't mention any RTC.

And what do you mean by "accurate"?

Thanks for the reply...I need the time of both the boards perfectly synchronised using any communication protocol between the boards. Since bluetoth low energy cannot be used for communication between two boards i think i have to go for RF or Zigbee. BTW 101 board comes with onboard bluetooth low energy

I need the time of both the boards perfectly synchronised

You haven't answered my question. What time??? Describe the notion of "time" that you are talking about.

"Perfectly synchronized" is not a meaningful answer to the question "how accurate?" That is a question that needs a numeric answer.

ashhark91: .I need the time of both the boards perfectly synchronised ...

You are out of luck then, Einstein says you can't get perfect synchronization if they are accelerating in respect to each other.

The best way is to use GPS which is about as "perfect" as it gets. Now, if "good enough" is OK, we can talk.

Even if you could perfectly synchronise your clocks ( and what does that mean? - check special relativity... even for devices which are stationary with respect to each other... )

• the normal frequency reference on an arduino is a ceramic resonator which has an accuracy of +/- 3% or so.

so they wouldn't stay in sync for long!

A RTC shield would be a help...

regards

Allan.

Hi sorry for not specifying the time. I need an accuracy of 30 microseconds. Can I give a master clock from an android application if communication between two arduino 101 is not possible?

BLE latencies are on the order of milliseconds and are not determinant. Getting synchronization on the order of tenths of a second should be straightforward, but synchronization on the order of tens of microseconds is going to be non-trivial at best.

A GPS receiver with a 1 pulse per second output at each node is probably the most straightforward way to get to microsecond level synchronization without a physical connection between nodes. This presupposes an outdoor application.

No it doesnâ€™t. It presupposes an external antenna. We have dozens of GPS antennas here where I work.

ashhark91: Hi sorry for not specifying the time. I need an accuracy of 30 microseconds. Can I give a master clock from an android application if communication between two arduino 101 is not possible?

You think an android app can define a signal to an accuracy of 30us???

Again I'm forced to ask "which clock?"