This an Open-Source multiplexor that will allow you switch between manual or auto mode using only one channel of your remote control, also include a "build-in" picoswitch with three states (down, middle and up) + reset mode, and all through one channel.

This MUX is intended to be use in low power and simple autopilot systems. In case your uController do not have enough timers to control servos, you should try the pololu servo controller and interface it with the DIY MUX.

The attiny firmware is also Open-Source and you can modify it as you wish, you will need winavr+avrstudio4 and of course an ISCP programmer, like this one.

To buy a PCB click here.

Part list from DigiKey:

3 x 1k SMD(0805) resistor P1.00KCCT-ND
1 x 10k SMD resistor P10.0KCCT-ND
1 x .1uf capacitor PCC1828CT-ND
2 x LEDs SMD(0603), the color is optional:
Red: 160-1181-1-ND
Green: 160-1183-1-ND
Blue: 160-1646-1-ND
1 x Attiny 85, ATTINY85V-10SU-ND
1 x Mux 74LS157 296-14884-1-ND

There is also an optional component (D1), (in the top of PSEL label on the schematics), this is just a protection diode, if you are not planning to use it you should make a solder bridge between the pads..

Eagle files:

Attiny firmware:

Just to remember, when i used to have no idea of basic PCB design rules:

Now i try to fallow some rules, for example NEVER use the autorouter. 100% by hand..

Views: 955

3D Robotics
Comment by Chris Anderson on December 6, 2008 at 8:12am
Sweet! Just to remind everyone, a "MUX" is a multiplexer, otherwise known as a "failsafe". It's a stand-alone board that switches control from RC to autopilot and back again on command, so you can regain manual control of your plane even if your autopilot goes on the blink.

3D Robotics
Comment by Chris Anderson on December 6, 2008 at 8:29am
Also, if it's not clear, this is an update of Jordi's earlier failsafe here.
Comment by Marty on December 7, 2008 at 6:30am
Excellent work Jordi. Are you guys planning on making this available for purchase or are you going to leave to us to DIY ?

Comment by Jordi Muñoz on December 7, 2008 at 7:11am
Hello Marty, well let see what Chris Anderson think about it. Would be nice to make a small, fully assembled stock and sell it like limited edition...


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