HUV Full Speed Wifi Interface

[JonHylands]

Well, after a lot of delays, its finally here!

http://www.huvrobotics.com/shop/index.php?_a=viewProd&productId=8

Feature List:

- full speed (1.0 mbps) bidirectional wireless access to to the bus
- onboard power terminal, power switch, fuse
- SYNC_READ command implemented onboard to reduce latency
- can handle most common wifi network security protocols (WEP, WPA)

You can read the manual here:

http://www.huvrobotics.com/BioloidWifi-UserManual-rev01.pdf

The price is $200 USD.

- Jon

[limor]

as always, We Stand in Awe Before your creative ingenuity


can you share some timing info ?
whats the latency, packet drop, continuous message (broadcast) vs. short message etc. etc. ?

[JonHylands]

I don't really have anything to measure the latency accurately. The socket code in Squeak Smalltalk is not great in terms of performance.

I hooked up my logic analyzer to the Tx and Rx lines on the wifi module, and doing a READ_DATA on a servo, asking for 2 bytes back, the time difference between the start of the request and the end of the response was about 1.6 ms, and that is with the default return delay time.

Of course the wifi module introduces its own latency. Pinging it generally gets responses in 2-3 ms.

My brother is buying one from me, so hopefully he'll update his command line utility to work with it, and then we can get a better indication of what the total latency is.

- Jon

[JonHylands]

I did some more playing around, using Wireshark (a network traffic analyzer). Over the span of 100 tests, doing a READ_DATA with 8 bytes of command, and 8 bytes response (2 bytes of data), I'm getting an average response time of 25.5 ms, with the minimum at 6 ms, and the max at 45 ms.

- Jon