Hello there, I'm using Arduino YUN to control the motor speed and I could connect to the network of Arduino YUN. At first time, I could control it successfully but when I tried to control the motor again, the motor didn't work but I could hear the sound of motor. The problem is that the motor didn't run but I think the Arduino YUN is working because I could connect to the YUN network. BTW, the motor is in good condition and the circuit is correct.
Is there any problem of Arduino YUN? Or it only can work for a while because when I run the motor at first time, the Arduino YUN was a little bit hot?
Thanks for your reply!
Think your drawing too much current and browning out?
What the circuit look like?
I just used sparkfun SIK Guide circuit 12 to control the motor and the circuit is attached below. BTW, I didn't use the diode in the circuit diagram because when I connected the diode the circuit can't work so I didn't connect the diode and the circuit is working.
circuit diagram.docx (380 KB)
Like to disclaim that I'm no expert, so others can correct me if I'm wrong about this.
In that circuit... Yes, I guess it is protecting the pin, but still drawing power from the Arduino power supply. It might be helpfull to note that the UNO might draw 20-30mAh when idle with little else attached and the Yun I have noticed might draw about 200-300mAh in the same situation.
This is a significant 10X difference, particularly when at 500mAh the polyfuse will be tripped on the YUN. The doc you attached says the motor could draw about 200mAh, this is cutting it close to tripping. To reset a tripped poly, you need to unplug for a minute to let it reset. After doing this check if you can wifi upload the the bridge sketch, see if you can blink the LED. Then try the motor again and pay attention to whether the motor is causing the problem. The other question that comes up is, what is your power supply rated for? Some cell phone chargers deliver less then 500mAh. This is just a strong nagging suspicion on my part, could be something else.
Ironically someone came to me with the same problem today. Ultimately, I found your answer!
Look at the example code that you are using. It requires you to open the serial monitor and type in a speed value.
Also, at the lower amperage the Yun will supply, you will need to hand start the motor to overcome inertial resistance. A more powerful power supply would eliminate this step. If you are hearing the motor, this is likely the issue you are having.
And leave the diode in, i'm sure its there for a reason. Kickback I think.
Thanks for your help! 
Glad you solved it! Can you please change topic to "[solved]" ?