Hi everyone - I'm a retired mechanical engineer and I have had a stroke that has left me with greatly reduced mental capacity. About a year I started an Arduino project and I'm just now trying to get back into it. I'm really struggling with my thought process and it appears to be a very steep up-hill battle. But it's wintertime and I'm stuck indoors so I'll try again.
There are many motor control shields on eBay and most of them are from China and may be very slow in shipping. I have found one http://www.ebay.com/itm/official-arduino-motor-shield-v3-/150991643509?pt=LH_DefaultDomain_0&hash=item2327cda375
that may possibly be shipped from the USA.
I can see by my records that I have made purchases from Adafruit Industries in the past but I don't remember. I have made purchases from other vendors but I don't remember any of them.
So here are my questions . . .
Would you buy that motor shield on eBay? Would you go to Adafruit for one? Can you make recommendations?
P.S. Please read this post very slowly as it took me FOREVER to type it.
Hi, I'm a Mechanical Engineer as well. I've just selected a motor shield: DFRobot 1Amp Motor Shield from dfrobot.com (or on robotshop.com). My recent research is based on using low power DC gear motors. Here are a few things to consider:
-For low power motors: Is the shield based off of L293 or L298 driver chip? L293 has a 600mA sustained or 1.2 Amp Max current per channel. L298 has a 2Amp sustained per channel. Both of these chips are capable of driving 2 DC motors. Also look at the voltage min/max range that is supported. The L298 has CurrentSense pins to give the microcontroller feedback on the current draw of the motor. These are sometimes wired up by the shield (like in the Arduino Motor Shield) and thus take up additional pins. Some L298 shields, like DFRobot 2 Amp, don't utilize the CurrentSense pins.
-Is the shield pre-built/soldered? The adafruit shield mentioned is great, but you must build it yourself. It's not overly difficult, but if soldering is not your friend, consider a pre-built shield. The Arduino Motor Shield and the DFRobot motor shields appear to be pre-built.
-Is the shield stackable and/or have female header already installed? The Arduino Motor Shield and DFRobot shields appear to have female headers to easily use unused pins or allow a differnt shield to stack on top of it (assuming no pin use overlap).
-Functionality: Do you need the motor to operate in both directions? Do you need speed control? Check for these things, altough I believe most of them can control speed with PWM.
-Price. The Arduino motor shield is expensive but has good support and existing examples.
-If you're driving higher powered motors, the game changes and the above advice doesn't fit with that scenario.
For me, my motors were DC 6V gear motors with a stall current of 470 mA, so a 1 Amp DFRobot shield made sense for me. I also liked having the extra pins available for my other sensors. Figure out your motors, then report back with a link or specs and we can further guide you. Good luck.