Hello, I’m starting to learn Arduino for a school project. I’m building a shooter but I’m not sure if the shield and power supply I have will be enough. I work with an Arduino Uno which is powered by a 9V battery. For shooting the ball, I must power 2x 6V MOT2N dc motors. There are 2 current given for the motor, one is 250 mA, and one is 1.34 A. For aiming I have a MG996R servo and a S3003 servo. The MG996R must rotate a load of 2-3kg. The S3003 must rotate a load of 600mg-1kg. I saw online that using a shield is good for powering motors, so I got a L293D motor driver shield. I power the shield with 4x AA batteries. When I look at the currents of the motors and servos, I think that the shield cannot handle the current. For the dc motors and servo’s, there are more than 1 current given online so I don’t know which current to use. Is this shield sufficient to handle the current or do I need a different shield?
Check the current rating of your specific shield.
If you must use the old and rather obsolete L293D driver, remember to add 2-3V to your power supply to compensate for the losses. Or get a modern, MOSFET based motor driver.
To see whether your shield can handle the current: check both stall and running current of the motors; the shield has to be able to provide at least the stall current as peak and the running current continuously. If those motors are loaded the actual running current will be somewhere in between the rated current (always unloaded) and stall current depending on the load.
Adafruit has an interesting new module that will do what you want: Overview | Adafruit Motor Shield V2 | Adafruit Learning System. an excerpt from the first page.
Instead of a L293D darlington driver, we now have the TB6612 MOSFET drivers with 1.2A per channel current capability (you can draw up to 3A peak for approx 20ms at a time). It also has much lower voltage drops across the motor so you get more torque out of your batteries, and there are built-in flyback diodes as well.
Instead of using a latch and the Arduino's PWM pins, we have a fully-dedicated PWM driver chip onboard. This chip handles all the motor and speed controls over I2C. Only two GPIO pins (SDA & SCL) plus 5v and GND. are required to drive the multiple motors, and since it's I2C you can also connect any other I2C devices or shields to the same pins. This also makes it drop-in compatible with any Arduino, such as the Uno, Leonardo, Due and Mega R3.
jorre_foets:
I work with an Arduino Uno which is powered by a 9V battery.
Very bad idea!
gilshultz:
Adafruit has an interesting new module that will do what you want: Overview | Adafruit Motor Shield V2 | Adafruit Learning System. an excerpt from the first page.
There's a period too much in your link. Corrected link here.
Pretty clever, they're basically using that PWM IC as pin extender for most of the control pins, and then on a few the actual PWM ability. Two motor drivers for total four motors on that board.
Note the lack of a huge heat sink that normally accompanies the L298N, that's just because the TB6621FNG is that much more efficient!
Instead of a L293D darlington driver, we now have the TB6612 MOSFET drivers with 1.2A per channel current capability (you can draw up to 3A peak for approx 20ms at a time). It also has much lower voltage drops across the motor so you get more torque out of your batteries, and there are built-in flyback diodes as well.
What does 1.2A per channel mean? Can is handel 1.2A in total or are there more than 1 channel so like 2.4 or 3.6A?
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One chip can control two motors; one motor is one channel. That shield would be able to handle 4.8A continuous, and 12A peak. Make sure your power supply is up to the job.
Do read the datasheet of parts you are not familiar with!
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