Help with High Torque Metal Gear Servo and nRF24L01

Projects Discussion and Showcase Robotics
#1

I am trying to control a servo motor wirelessly with a nRF24L01 module with a joystick, however, the servos don't seem to move. Problem: The servo motors are not moving in response to the data received from the controller.

Equipment: 1 Arduino Uno 2 Duracell 9v alkaline batteries (one to power the servo motors, one to power the joystick shield) 2 DS3218 Metal Servos (High Torque (20kg-cm), rated 4.8v-6.8v)

Troubleshooting results: All wiring is good (I checked) The servo motors work with the Sweep example (It works but not great. It's not as powerful as it should be) (Wireless connection seems to be the problem) Other servos work, but I need to use these metal servos because they are high torque. The metal servos do work (I've tried it using a standard RC system and it functions as normal) I made a voltage divider for it, yet no movement (So not a problem with the power source) Trying to servo.write(some position) doesn't do anything (So maybe the problem lies here?) Also one strange thing, I can hand rotate the servo arm, but when I get to a certain position (I assume it is the position I set it to) it locks as if it knows where the position is, but just can't move there.

Question: What function do I need to use to rotate the servo when I move joystick one direction and rotate it back the other way when I move the joystick in the opposite direction?

If you need any more clarification, feel free to ask. I've just spent too much time on this so I'm not being as specific right now.

#2

9V batteries are totally unsuitable for motors or servos, and the voltage is too high for that servo (6.8V max).

For one servo, a 4xAA battery pack is fine, and might work for two if they are not moving at the same time.

Otherwise, you will need a 5 to 6V regulated power supply capable of supplying at least 2 Amps.

Connect the servo power supply negative lead to the Arduino ground (as well as the servo).

#3

Power is definitely a problem. If you need maximum power from those servos 2 x LiFe batteries or 5 x AA NiMH rechargeables will work better than alkaline AAs because those will servos need a lot of current to get moving.

You also need some code. If you post the code you are using we can check if there are any problems there. It may be best first to write a simple program without the nRF24L01s which just moves the servo(s) to a few specific positions which will check that power and wiring are o.k. Then you can add in the wireless part and check that you are sending and receiving the data that you think you are.

Steve

#4

Hi,

Can you please post a copy of both of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Please include your power supplies.

Thanks.. Tom... :)

#5