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Can I transmit and receive at the same time? Does this vary by silicon vendors?

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  • \$\begingroup\$ According to bluetooth.com/Pages/Fast-Facts.aspx yes, it's full-duplex. \$\endgroup\$ – KyranF Oct 4 '14 at 22:06
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    \$\begingroup\$ No, you cannot receive while transmitting. However the protocol stack will take care of managing the timing of the actual transmissions in each direction, so for a usage perspective you can have bidirectional data flows in some modes. \$\endgroup\$ – Chris Stratton Jul 25 at 18:39
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This questions requires a bit more knowledge of Bluetooth than just its existence, I am not entirely confident a simple and straightforward answer here will clarify enough.

Simply put: Yes, physically (that is, in the 'physical layer'), all BlueTooth standards are created as full-duplex. At least as is apparent to the layers above. (some details/caveats left out, because I am not writing a full white-paper here)

However...

When using the low energy system, single mode devices may not be able to, especially when they implement a service that only receives or transmits. So, maybe, in your case, the answer is no.

But it still might be yes, if you are talking about a BlueTooth 4.0 / BLE enabled phone or PC, they most usually implement dual mode and full service stacks, allowing them to use full-duplex services, half-duplex services either in or out, etc etc (whether the software designer thought it was useful to allow your PC to act as the device in the heart-monitor service can be doubted of course - or in fact they thought to allow your PC to be a slave at all).

If you want to really understand how BlueTooth works and specifically BLE, you should really read up on a good source. I don't know any on-line "For Dummies"-like resource, so I can only point you to the BlueTooth organisation itself (no happy stories about bunnies and ponies, but all the raw info you need):

the Bluetooth Smart Universal Page

More specifically:

the Bluetooth Smart Developer getting started Page

Even more specifically:

the Bluetooth Smart Developer Page about overview of operations

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  • \$\begingroup\$ Actually, it is not full duplex; it only appears to be at higher levels. The radio itself can only be in transmit or receive mode at any given time. Fine grained time-slicing makes communication bi-directional, but the actual transport is in no way full duplex. Actual full duplex radios are very hard to engineer given the drastic difference between transmit and receive levels, making something essentially "just not done" unless there is a very strong need. Typically it's better to just use a wider band signal to move the data in one direction at a time. \$\endgroup\$ – Chris Stratton Jul 25 at 18:35
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Each Bluetooth module has one name and can only do one. Tx or RX that is it. I use 2 modules 2 different manufacturers because of the name or same mac address.

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  • \$\begingroup\$ This seems to be a confused to attempt to generalize from some particular fixed function module with unusual limitations, in a way that does not address the question which was actually asked. \$\endgroup\$ – Chris Stratton Jul 25 at 18:40

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