Hi,
I am just trying to understand the purpose of a motor shield.
Can't you do everything you want without a motor shield?
Do you still have access to all the Arduino pins if a MS is installed?
Thanks!
J
I used an RS stepper motor 191-8299 driven from four FETs connected directly to the outputs of the Arduino. Speed and direction control has to be done by the Arduino.
Apparently the motor shield does all of the control for you like forward and reverse and speed. Also it controls the current (by chopping) to the low impedance windings of a stepper motor.
The above stepper (191-8299) does not have low impedance windings and is 12volts per phase.
High Torque permanent magnet types have low impedance windings and run off something like 2.8 volts per phase
Hope this helps
Dead_Ard
jesse68:
Hi,
I am just trying to understand the purpose of a motor shield.Can't you do everything you want without a motor shield?
Do you still have access to all the Arduino pins if a MS is installed?
Thanks!
J
A motor shield amplifies the weedy little Arduino's 0.02 Amp output up to 1.00 or 10.00 or 20.00 Amps. Most motors won't even get warm if they are connected only to the Arduino output. They certainly won't move.
Shields pass all signals through the stack. Yes you can access the pins. But a pin in use for a motor shield won't be useful to read a thermometer or anything else. The Adafruit shields are very good at controlling many motors with minimum usage of pins.
I have two motors with my Arduino Motor Shield. One of them is a normal DC motor that operates with PWM and the second one is a Stepper motor. Can I run both of them with same motor shield ?
If NO, how can I run with a DC and stepper motor from Arduino?
Don't attempt to use the Arduino motor shield for a stepper. Yes, it does work for some steppers but it doesn't work well.
Add a Pololu DRV8825 stepper driver to your stack. Unfortunately it's not a shield but a separate (small) board.
It seems that it works for others!
I have a Bipolar stepper motor, what is the limitation if I use the stepper motor with Arduino motor shield?
I need a solution now or today, the driver from Polou will take me many days to revived since I'm in DK and they delver from US. Is there other alternative solutions ?
What is the resistance of the stepper? Low, like 3-5 Ohms is not going to work well. High, like 20-50 Ohms will work with that driver.
Pretty much everything on Instructables is entertaining but the actual engineering is worthless. I sometimes get ideas from there but 60% of the stuff I see is going to explode in flames a few minutes after the camera is turned off.
It is 12 VDC and 7,5 Ohm..! So if the resistance is high the more stable is the system in this case ?
Hmm it is true also from some of my experiences, but I'll try and see.
MorganS:
Most motors won't even get warm if they are connected only to the Arduino output
You forgot to mention that the Arduino is very likely to be damaged because the motor will overload the I/O pins.
...R
Mobile_robot:
It seems that it works for others!http://www.instructables.com/id/Arduino-Motor-Shield-Tutorial/step6/Stepper-Motor/
https://www.youtube.com/watch?v=6KLXMbRm-l0I have a Bipolar stepper motor, what is the limitation if I use the stepper motor with Arduino motor shield?
I need a solution now or today, the driver from Polou will take me many days to revived since I'm in DK and they delver from US. Is there other alternative solutions ?
Listen to what we are saying - don't use a motor shield to drive a stepper motor, its frankly rather crap
at best. These days stepper drivers are cheaper than motor shields, and way way more performant
for modern bipolar motors. If you have a NEMA17 stepper in the 1 to 3 ohm range a DRV8825 stepper
module is spot-on, costs a few peanuts on eBay (yes, more reliable sources are available, at a cost).
If you must drive with a motor shield you must get a high impedance (30 to 50 ohm) stepper motor, and you
must run from 12V, and you won't get more than about 200rpm at best, probably 100rpm in practice.
Normal stepper motors these days are low impedance and you'd run from a DRV8825, A4988 or other chopper
driver from 12, 24 or even 36V supply (more volts = faster top speed).
Thanks for your advice MarkT and MorganS
I think that I had success by using a Motor Shield with a stepper motor from: https://www.amazon.com/42X42mm-Degree-Stepping-Stepper-Motor/dp/B018HLHN8A
and the code from:
"Here is code to make the stepper spin in one direction:"
But the movement isn't smooth, and when I turn on the 12 v external power then it makes noise which I think it should not flash the LED on power supply (that means short circuit). It runs OK only with power from USB. Maybe it is because of the low internal resistance in motor as you mentioned!
My next step is to compare Motor Shield performance with DRV8825.
These links may be of interest
Stepper Motor Basics
Simple Stepper Code
...R