Trying to wrap my around what the motor shield gives you. From reading other posts it seems like the Arduino can run 8 servos at default. If you add the motor shield you can run 2 servos from it. Does that mean with the motor shield attached you can still only run 8 servos? If so is there any point to the shield if your mainly running servos?
The motor shield has:
2 connections for 5V 'hobby' servos
All 6 analog input pins are available. They can also be used as digital pins (pins #14 thru 19), assuming these can run servos with the shield attached.
Thanks in advance.
Motor Shield
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- adafruit_support_bill
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Re: Motor Shield
The motor shield provides convenient connection headers for two servos. If you need to run more than that, the motor shield is not the best choice. You can run up to 12 servos directly from the Arduino using the servo library. Each servo will require one pin. To control more servos with fewer pins, there is the Adafruit Servo Shield. This will control 16 servos using 2 pins. You can stack these shields to control as many as 992 servos using just 2 pins. http://www.adafruit.com/products/1411
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Re: Motor Shield
Thanks, that clears up a lot.
So if I wanted to power/control:
18x servos
4x motors
Thinking I would want 2 servo shields and the motor shield.
Is that realistic with 1 arduino/battery? If so, which shields/battery would you use?
Again, appreciate the help!
So if I wanted to power/control:
18x servos
4x motors
Thinking I would want 2 servo shields and the motor shield.
Is that realistic with 1 arduino/battery? If so, which shields/battery would you use?
Again, appreciate the help!
- adafruit_support_bill
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Re: Motor Shield
For that many motors/servos, you will probably want to have a separate power supply. Motors and servos are both power-hungry and electrically noisy and can cause erratic operation of the processor.
To decide on a power source, you need to answer a few questions:
What are the specs of the motors will you be using (voltage, stall current)?
How many motors will be running simultaneously?
What size servos will you be using?
How many servos will be moving simultaneously?
To decide on a power source, you need to answer a few questions:
What are the specs of the motors will you be using (voltage, stall current)?
How many motors will be running simultaneously?
What size servos will you be using?
How many servos will be moving simultaneously?
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Re: Motor Shield
2 motors at a time with these specs:
Voltage: 3 - 12 Volts
Gear Ratio: 10:1
Stall Torque: 16.8 oz-in. (@ 12V)
Speed: 303 RPM (@ 12V)
No Load Current: 95 mA (@ 12V)
Stall Current: 0.5A (@ 12V)
Insulation Resistance: 10 MOhm
Dielectric Strength: 300VDC
DC Reversible
At any given moment about 3-8 servos at a time, nearly all the servos are standard size.
The motors and servos may be active at the same time as well.
Voltage: 3 - 12 Volts
Gear Ratio: 10:1
Stall Torque: 16.8 oz-in. (@ 12V)
Speed: 303 RPM (@ 12V)
No Load Current: 95 mA (@ 12V)
Stall Current: 0.5A (@ 12V)
Insulation Resistance: 10 MOhm
Dielectric Strength: 300VDC
DC Reversible
At any given moment about 3-8 servos at a time, nearly all the servos are standard size.
The motors and servos may be active at the same time as well.
- adafruit_support_bill
- Posts: 88145
- Joined: Sat Feb 07, 2009 10:11 am
Re: Motor Shield
You can run all of them from a 5-6v power supply - although you will not get full torque from your DC motors at that voltage.
Standard size servos can draw 1A or more when starting, but typically less than 0.5A when moving under moderate load. Based on the combined load of <=8 servos and 2 motors, I would suggest either:
one 5v @ 5A supply.
-or- (for maximum DC motor torque)
one 5v @3A supply for the servos plus one 12v 1A supply for the DC motors
Standard size servos can draw 1A or more when starting, but typically less than 0.5A when moving under moderate load. Based on the combined load of <=8 servos and 2 motors, I would suggest either:
one 5v @ 5A supply.
-or- (for maximum DC motor torque)
one 5v @3A supply for the servos plus one 12v 1A supply for the DC motors
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Re: Motor Shield
Do you know where I can find batteries for arduino similar to what you recommended? The closest I've found is:
http://www.dfrobot.com/index.php?route= ... wh4BvldWSo
http://www.dfrobot.com/index.php?route= ... wh4BvldWSo
- adafruit_support_bill
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Re: Motor Shield
If you want to run on batteries, you have to work in mutiples of single-cell voltage. LiPo cells are 3.7v, so the combinations are limited. NiMH cells are 1.2v, so packs are available in a wider variety of voltages.
Most servos will run on either a 4.8v or a 6v pack. Some will handle 7.2v or 7.4v, but not all of them will.
4.8v battery packs: http://www.all-battery.com/48vnimhbatte ... eries.aspx
6v battery packs: http://www.all-battery.com/6vnimhbatterypackseries.aspx
And for the steppers, 12v packs are pretty common too:
12v battery packs: http://www.all-battery.com/12vnimhnicdb ... eries.aspx
(I don't have any experience with all-battery.com, but there are many other on-line battery vendors with similar selections.)
Most servos will run on either a 4.8v or a 6v pack. Some will handle 7.2v or 7.4v, but not all of them will.
4.8v battery packs: http://www.all-battery.com/48vnimhbatte ... eries.aspx
6v battery packs: http://www.all-battery.com/6vnimhbatterypackseries.aspx
And for the steppers, 12v packs are pretty common too:
12v battery packs: http://www.all-battery.com/12vnimhnicdb ... eries.aspx
(I don't have any experience with all-battery.com, but there are many other on-line battery vendors with similar selections.)
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Re: Motor Shield
Great thank you for the help.
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- Joined: Mon Apr 15, 2013 3:18 pm
Re: Motor Shield
Are there any good non-battery options for variable voltage/amps in this range? To make this robot hand work I used a voltage regulator device, however those type cost several thousand, so wondering if there are less expensive options?
- adafruit_support_bill
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- Joined: Sat Feb 07, 2009 10:11 am
Re: Motor Shield
Computer ATX power supplies are fairly common and inexpensive. If you look around you can probably salvage one from an old computer for free. These typically supply 3.3v, 5v and 12v.
Please be positive and constructive with your questions and comments.