I’ve used other robot kits with arduino boards (like the actobitty 2wd robot) that have separate power sources for the motors and the arduino board (9v for board, 4xAA for motors). Since the Rover powers everything from a single source, what is the best way for me to power a servo motor without the possibility of a returning voltage from the servo and possibly damaging the board? For example, when I wired a servo motor’s power pin directly to my arduino Uno on another robot, whenever it met any resistance, it returned voltage and triggered other electronics, so I attached the power pin to the wheel motor batteries and it fixed my problem. I was advised on the Arduino forums that you should never have a servo powered directly from the 5v/3.3v arduino pins for this reason. Or are the 5v solder points protected from this?
If the servo is relatively small and won’t consume much power (for example being used to pan a sensor), you can power it from one of the digital pins. Note that micro servos actually consume more current than many standard sized servos such as the Hitec HS-422. If you plan to use the servo to lift an object, or any other application where the servo will consume more than around 50mA, we’d suggest a second power supply; be sure to connect common ground. The IO shield is quite helpful for this.
Sorry to hi-jack this thread but my question is related. Like the OP I am wanting to connect the Sharp IR sensor (Sharp GP2Y0A21YK0F) to the Rover V2 Bluetooth variant kit. The autonomous variant of the Rover V2 doesn’t sport the sensor package I want. Too much actually. I just want simple forward range detection. I was going to pick one of the micro servos but then I saw you comment that they draw more current than a standard, larger servo. I hadn’t paid attention to that but I am now! I’ve used the HS-422 standard servo, in fact I probably have a few extra ones from my RC projects. But it appears the Rover V2 doesn’t supply a nice ready-to-connect connector like it does for other components such as the motor encoders (which I also plan to get) So we we need to strip the HS-422 servo wires and manually connect to the available pins on the Arduino board (pwr, gnd, signal)? I know you mentioned the I/O expansion board but I wanted to keep this first revision simple (and cheaper).
Also is there PWM code already written to drive the servos? I assume that nut has been cracked too so thought I’d ask up front.
EDIT: Whaaat! There’s a servo library for the Arduino. Nice. Just found a reference to it in another thread. Be easy on me, I just started researching this stuff yesterday. My background is PIC but even that was years ago. Couldn’t even spell Arduino before yesterday (literally)! Tons of info out there on this popular platform.
-Steve
So long as the servo is really under minimal load (like the sensor and bracket) you can connect all three pins to digital pins on the Arduino, set the one connected to GND to low, the one for power to HIGH.
This takes up extra digital pins, but should work.
You should not need to cut the wires, at most, use cables between the servo’s connector and the appropriate pins on the board.
Good call. That makes more sense then destroying the servo cable anyway. But we’ll definitely do what you suggest and connect up to 3 Digital outs.
-Steve