[CFC] : Pypot WIFI Mini module

Technology
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For the “School of Moon” dance project, there is a need to control, via WIFI, 4 Bioloid humanoid robots. The bioloid are sold with software to control the robot via serial link or XBee or Bluetooth but no WIFI.
Moreover, the software is not very stable and it is not possible to control several bioloid with only one interface.
I submitted the subject to someone of the Toulouse Artilect Fablab which has the idea to control the robot via WIFI with small WIFI modules connected directly to the DXL bus (via openCM9 for the moment)

Do you think it is possible to remove the raspberry Pi to replace with a kind of “WIFI USB Hub” ?
Has anyone tested this ?

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Your Idea is to replace the actuals USB2AX with a kind of WIFI2AX?

This is probably possible with the openCM9 and a wifi serial interface… I don’t know exactly how to manage wify like that…

USB2AX use ATMEGA328P controler, exactly like Arduino uno. You could also use arduino wifi shield…

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hi @Thot, seems to be a great idea!
I would see a SAMW25-XPRO perfect for that because it could be seen as both Arduino Zero and Arduino Wifi101.
I thought it was available but unfortunately the stock is set to 0 at the moment: http://www.atmel.com/tools/ATSAMW25-XPRO.aspx

I think it could be very fast to obtain something working by integrating this board with Arduino Zero, Wifi library and some DXL library: http://www.pablogindel.com/informacion/the-arduinodynamixel-resource-page/

I remember having seen also some Serial to Wifi hardware modules but not sure how the needed RS-485 should be integrated in that case.

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Usb2ax does not use a 328p, it uses a 32u2, closer to the 32u4 of the Leonardo (without I2C or Analog inputs).

For a wifi controller, HUV robotics did one a long time ago. I don’t think any remain available though, but the whole source code is open - if a little bit lost among other things - and can be accessed on https://github.com/dhylands/projects

It would only work for an open loop controller (too much possible delays in any data that would come back to be useful for closed loop), and even then only when there aren’t too many signal interferences, but I guess in this case it would be ok.

Maybe you could have a look at using other parts of the spectrum that would not be affected by the ubiquitous 2.4gHz.
I’m thinking about something like this: http://freaklabs.org/index.php/blog/misc/wrecking-crew-orchestra-cosmic-beat-behind-the-scenes.html

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Thanks for your help, we are looking at it closely. It could be a good solution for light Poppy creatures.

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It could also lower the cost for a those lighter creatures if it can replace the Raspberry Pi.

I looked for a Serial over WIFI module and I found two good contenders :

  • ESP8266 in transparent bridge mode : they are really cheap (< 3€) and sold everywhere (here on Aliexpress), but the transparent bridge mode need a firmware flashing.
  • USR WIFI232 : a little more expensive but the transparent bridge mode is the default one.

Here’s a Gist explaining a similar setup (for a nodebot) using the USR WIFI232 module. He also explain how Socat can be used to create a virtual serial port that relay the commands to a TCP socket. That way pypot could be used as is.

We also need the additional circuitry to convert the UART to half duplex, but the components (74HC126 and 74HC04) are also really cheap.

What do you guys think ? I’m a total newbie in electronics, so correct me if something does not make sense.

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This is a good idea, that event chance to work… I think electronicaly it’s ok. If you plan to do it, please share your experiments with us.

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The solution with ESP8266 was the solution we wanted but we had a new requirement to play sound inside the robots. The raspberry Pi card has a better chance to be chosen.

But with the first tests, an ESP8266 + OpenCM9.04 to manage embedded trajectory generation could be a great solution (we did not have time to finish the prototype)