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When I read the book about the Data Transactions,

It mentions that once the connection is made, both devices can go into deep sleep between transactions.

I dont quite understand how this could happen during the transaction. Can anyone explain this?

Thanks

Youssif Saeed
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Sam
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  • stackoverflow isn't the best place to answer such types of questions. A better place would be http://electronics.stackexchange.com/ – Youssif Saeed Apr 14 '14 at 16:25

1 Answers1

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A primary difference between Bluetooth and Bluetooth Low Energy is that the latter was not optimised for sending long data streams. In other words, Bluetooth Low Energy was optimised for sending blocks of data every "once in a while". The frequency of sending the data is application-dependent and can be modified by the user. For example, a BLE device can send a block of data (e.g. current temperature reading) once every five minutes, and then go to sleep (where there is very minimum power consumption) before waking up to send data again, and so on. This duty cycle is one of the main reasons of the Low Energy factor of BLE as opposed to traditional Bluetooth.

enter image description here

As you can see in the image above, BLE data transfer is in the form of data chucks, and the BLE device can go to sleep between the transmission of those chunks.

There are a couple of useful resources out there on the theoretical aspect of BLE, and I particularly found the following two useful:

I hope that this helps.

Youssif Saeed
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  • Thanks for your feedback. Would you mind to explain "duty cycle" in detail here? – Sam Apr 15 '14 at 09:22
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    Duty cycle is the ratio of time in which the signal is active (in percentage). The formula is (duty cycle = (time signal is active/total period of signal)X100). For example, if a BLE device sends data for 1ms then sleeps for 999ms, then the (duty cycle=(1/1000)*100) = 0.1%. This is much much lower relative to classic Bluetooth, especially when there is a continuous stream of data! Hence the ultra low duty cycle of BLE is one of the main factors for its low energy consumption. – Youssif Saeed Apr 15 '14 at 09:48
  • Both links are broken. – rrrrrrrrrrrrrrrr Aug 25 '23 at 12:26