Input Voltage vs Servo/Motor Voltage for Romeo BLE (DFR0305)

mike.aboushanab 2018-02-09 07:23:33 2073 Views2 Replies
I found a $15 mountable 3D printed adapter on eBay to connect my Dewalt Max 20V batteries to anything. The print allows the batteries to clip in and out and has +/- power leads. I thought these would be great for the robot build because I already have many batteries and chargers, and they pack a punch.

Originally I was going to use an UNO R3 that I had and purchase a motor shield but instead opted for the Romeo BLE. I plan to run OSEPP tank treads with two 9V motors and some servos and sensors.

From the Romeo BLE (DFR0305) specs, I can see:
External Power Supply Range: 5-23V /* Dewalt 20V is < the 23V max here */
DC output: 5V/3.3V

I'm nervous to hook up ~20V to the board and blow 3.3v and 5v components.

Is the input voltage on the board regulated so sensors would still receive 3.3/5V?
Would the motor outputs just pass the full voltage?
(Will I be sending 20V to the motors or would I only output 5V max?)
Should I add a DC-DC Buck/Boost in between the 20V battery and the Romeo board to lower the voltage to say 9V which is what the motors are rated for?

THANKS!!

2018-02-11 06:36:34 I tried to google how to use the motor driver chips to decrease the voltage and could not find any examples of how to do this, can you help point mean the right direction? Most of what I read about PWM is that you can adjust the rate of the pulse to provide a different average voltage which drives the motor at a different speed. Are you implying that I can slow the pulse to get an average voltage <9V to operate in the motors range? It seems I would be sending a narrow pulse but at ~20V and I am not sure how that would affect components. I am hoping I am missing a variable somewhere the I could use to step it down. Also would this generate too much heat on the board? I just wonder why the board would be designed to accept 23V if it could not somehow be regulated.

Thanks for the help!! mike.aboushanab

2018-02-09 15:50:01 The external power is 5-23V and there are two motor driver chips which will decrease the voltage to fit for 9 V motor, but you need to attention the right socket for the external power. robert.chen