I am using the Mini Maestro 18-Channel USB Servo Controller to build a small humanoid robot.
The space to include batteries and boards is VERY limited, so I would like use a Raspberry Pi Model 3A+ but may need to use an Arduino Nano since the Raspberry Pi will not fit without modifications to the plastic body. I’d rather use the Raspberry Pi so I can code directly in Python without additional effort, but either way, if I can power with one power source (battery) that would be ideal.
So the question is, how do you split the power and control both the Pololu Maestro 18 Servo Controller board AND the Raspberry Pi (or Arduino) from the same battery?
I am using 16 servos as below:
- EMAX Original 12g Mini Metal Gear Analog Servo
- Operating voltage: 4.8V~6.0V
- Connector type: Futaba/JR compatible
- Operating speed: 0.12sec/60º at 4.8V; 0.10sec/60º at 6V
- Operating current: 200mA/60º
Is it as simple as having a single battery and splicing wires? (which is not simple for me since I have no idea yet how to do that…and links or instructions will be welcomed!)
Any recommendations on battery specs? Is 6 Volts too much? I think the Pi runs off of USB and is 5v, but perhaps you can power it from the GPIO pins? (which have a 3.3v or 5v pin) The servos are 4.8 - 6v.
For amps, how many will be needed? I believe the Raspberry Pi needs 1 amp and the servos may not all be working simultaneously. I found this on the Raspberry Pi 3A+ - Input power: 5V/2.5A DC via microUSB connector, 5V DC via GPIO header, (but I also read that it is ‘dangerous’ to power it via GPIO)
Will any of this be an issue for the Pololu board? Does the power pass through one device and into the other device, or just “fork” from a split point from the battery?
My battery options / ideas are:
#1. 4 AA rechargeable batteries in a custom case (appox 4.8 volts i would guess since rechargable batteries are 1.2v i believe?)
#2. somehow splice the current from a power bank (5v) power source (like you use for a phone, but not sure if this is enough amps? …this works for just a Raspberry Pi alone)
#3. use a 6v battery with JR (futaba) connectors, and somehow figure out how to add a USB out to the Raspberry Pi from that battery in parallel.
Other (and better) ideas are welcomed.
I apologize if I am not making sense, I do not know a lot about this…and I am sure there is a better way to do this.
If all else fails, I’ll try to use the 2 power sources, but this will be difficult for the robot due to the weight and balance issues.
Your help is appreciated!