The Wixel looks like a great product. One question I have about it (and other wireless like Xbee, bluetooth) is if it is capable of true simultaneous full-duplex communication, i.e. can two independent comm streams be active at the same time on the uart tx and rec pins, or must outgoing and incoming packets wait on each other?
The radio of the CC2511 microcontroller on the Wixel is not full duplex. It can not transmit and receive at the same time. Also, radio packets will sometimes be lost, so the packet will need to be retransmitted if you want a lossless communication pipe. We have Wixel apps that take care of those details for you, and if you are writing your own Wixel app then you can use the radio_link library.
However, the UART of the Wixel is full duplex which means the Wixel can send and receive serial bytes at the same time. In our apps, there is a 256 byte buffer for receiving bytes on the RX line and a 256 byte buffer for sending bytes on the TX line.
As long as your data rate is not too high, you shouldn’t have to worry about outgoing and incoming packets waiting for eachother and you can treat a pair of Wixels running the Wireless Serial App as a full-duplex serial link.
I’m not sure about XBee or Bluetooth but I think the technology they use is probably pretty similar to the Wixel so I would be surprised if the radio protocol is full duplex. I think that would require the radio to operate on two different frequencies at the same time. FYI, USB isn’t full duplex either.
Thank you David for the clear explaination. I can see where on the RF side, full duplex would get to be more complex, expensive, etc.