The continuous rotation (CR) servo trigger is a small robotics board that simplifies the control of hobby RC servo motors. When an external switch or logic signal changes state, the CR Servo Trigger is able to tell an attached servo motor to move from position A to position B. To use the CR Servo Trigger, you simply connect a hobby servo and a switch, then use the on-board potentiometers to adjust the start/stop positions and the transition time.
You can use a hobby servo in your projects without having to do any programming!
This is a servo trigger preprogrammed with the continuous rotation logic. With this little board you will be provided an easy way to deploy continuous rotation servos into your projects!
The heart of the CR servo trigger is an Atmel ATtiny84 microcontroller, running a small program that implements the servo control features designed for continuous rotation servos. On board each of these CR Servo Triggers you will find three potentiometers: A,B and T.
The default mode implements toggling control. The trigger initializes driving the servo as instructed by trimmer A. When the switch closes, it transitions to the speed indicated by B. When the switch closes again, it returns to A. The time taken to get between A and B is selected using trimmer T, which ranges from nearly instantaneous to 10 seconds, allowing the motor to gradually slow, stop, and reverse. This behavior can be changed by flowing solder between the pads of the mode jumper. With the solder jumper closed, the mode changes to bistable control – the servo will drive at speed A while the switch is open, and speed B while the switch is closed. While the switch input stays in a state, the servo drives at the corresponding speed – it is stable in two different states.
Compared with a servo motor, the CR servo trigger board draws very little current, roughly 5mA at 5V. Be sure to note that if you’re using the CR servo trigger to control your motor, the absolute maximum supply voltage that should be applied is 5.5 VDC. Additionally, it is designed to make it easy to daisy chain boards – you can simply connect the VCC and GND pads on adjacent boards to each other.