Hello everybody.
I suppose there a several way to use Arduino on Meccanoid:
-(1) Using Arduino in place of MeccaBrain: Arduino<->Smartmodule, in this case the link is serial, using the library provided by Meccano. In this case, you can use a smartmodule (servo or led) from Meccano, and to drive it with an Arduino board. You do not use your MeccaBrain.
-(2) Using a non-Meccano servo (standard servo) and Arduino: Arduino<->Servo. Use standard library, but no link with Meccano on anay side. I suppose it's not the goal

-(3) Using a non-Meccano servo to connect it to MeccaBrain. The Arduino is used to "translate" the link:
MeccaBrain <-- Meccano protocol -> Arduino <- standard serial or anything else -> Standard servo
In the last case, the Arduino has to "speak Meccano" to the MeccaBrain, and is connected to the servo as usual (using standard library). The main work to be done is to program the Arduino as an interface, so it has to receive the MeccaBrain frames (serial), and to answer to it (reading the protocol, it's still serial, but looks like Manchester Protocol: 1 or 0 s coded by the "High" time, the bit time is constant. For the received frame, it looks like standard serial: 1 is High level, 0 is Low level.
As conclusion, the Meccano library has to be "reversed", as the library is for case (1). in case (3) you have to receive Meccabrain frames and to send "servo" frames, it's just the opposite direction as the library. But I think it's not so hard to program.
But at the end, even if your Arduino is "concidered" as a smartmodule by the MeccaBrain (and it's what I want to do!), we still not have any way to program the MeccaBrain! When Meccano advertises on "open source", it's a trick: they do not yet give any way to program MeccaBrain! I hope they will produce a "programming tool" once a day. But I'm waiting for it!
Well, I hope to have been clear enough.
By the way, sorry for my "frenchglish"
