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Arduino Motor Shield for Tetrix motors
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Arduino Motor Shield for Tetrix motors

by weiliu on Fri Jun 29, 2018 2:12 pm

Hi,

I am new to Adafruit Arduino Motor Shield V2, and I have two quick questions:

(1) Can I use it to control these Tetrix motors shown here:

https://www.tetrixrobotics.com/Motors/T ... Gear-Motor
https://www.tetrixrobotics.com/Motors/T ... th-Encoder

We use TETRIX® MAX 12-Volt Rechargeable 3,000 mAh NiMH Battery Pack, like this one:

https://www.pitsco.com/TETRIX-12-Volt-R ... ttery-Pack

(2) Can you provide any links (websites or youtube) to show that the shield has been used for Tetrix motors?
(3) Do we have to do some soldering work to use it with our Arduino Uno? If yes, why? I noticed that there are some other Motor shields which do not need soldering...

weiliu
 
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Re: Arduino Motor Shield for Tetrix motors

by adafruit_support_bill on Fri Jun 29, 2018 2:21 pm

The Tetrix motors will overload the shield. You need a motor driver with more current capacity. The DRV8871 would be a good choice:
https://www.adafruit.com/product/3190

(3) Do we have to do some soldering work to use it with our Arduino Uno? If yes, why? I noticed that there are some other Motor shields which do not need soldering.

Our shield does require soldering of the headers. That gives you the option to build it with regular or stacking headers - or to use it un-stacked and connected via jumpers.

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Re: Arduino Motor Shield for Tetrix motors

by weiliu on Fri Jun 29, 2018 3:21 pm

Is the DRV8871 an addition to your motor shield V2, or it is a totally different product? Does it work with Arduino?

weiliu
 
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Re: Arduino Motor Shield for Tetrix motors

by adafruit_support_bill on Fri Jun 29, 2018 3:28 pm

The DRV8871 is a separate product. Instructions for use with an Arduino can be found in the guide: https://learn.adafruit.com/adafruit-drv ... =all#usage

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Re: Arduino Motor Shield for Tetrix motors

by weiliu on Fri Jun 29, 2018 3:43 pm

Thank you so much for the quick response.

I just found this video (Motor shield to control two Tetrix motors, seems no break-out is used) : https://www.youtube.com/watch?v=7WKmLOIdSnQ

Do no know if it is your motor shield or not. Is there an overload issue here? Pls. make a comment about its use.

weiliu
 
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Re: Arduino Motor Shield for Tetrix motors

by adafruit_support_bill on Fri Jun 29, 2018 4:09 pm

The motors in the video are not running under load.

The no-load current for those motors is about 0.7 which is well within the 1.2A continuous capability of the shield.
The manufacturer lists the 'load current' as 1.37A - which would overload the shield.
There is no stall current listed , but I have measured these motor before and the stall current can reach 6A or more. That is consistent with the chart on the spec sheet -and would be a serous overload condition for the shield.

The DRV8871 has current limiting which can be set as high as 3A. This will protect both the motor and the driver from stall current overloads.

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Re: Arduino Motor Shield for Tetrix motors

by weiliu on Fri Jun 29, 2018 4:25 pm

Thank you so much for the detailed information.
One more question, how many DC motors can one DRV8871 control?

weiliu
 
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Re: Arduino Motor Shield for Tetrix motors

by adafruit_support_bill on Fri Jun 29, 2018 4:54 pm

The DRV8871 can control just one DC motor.

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Re: Arduino Motor Shield for Tetrix motors

by weiliu on Sat Jun 30, 2018 10:49 pm

Thanks. Two more questions:

(a) What if we want to control a robot, which usaully has at least two wheels/motors? Can we use multiple DRV8871 to control motors? if not, do you have any other options to use Arduino to control Tetrix motors?

(b) Back to the Tetrix motor overload issue we discussed in the previous emails, how can we know if our robot will run into overload or not overload situations? Any way to predict and how? For example, if our Tetrix robot only has a PC (laptop and small type) on it, and runs only on a flat surace, will we run into overload issue?

weiliu
 
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Re: Arduino Motor Shield for Tetrix motors

by adafruit_support_bill on Sun Jul 01, 2018 6:19 am

(a) You can use multiple DRB8871's. You will need 2 GPIO pins with PWM capability to control each one. (On an Arduino UNO, the PWM pins are 3, 5, 6, 9, 10, and 11)
(b) Overloads are hard to predict.
When starting a motor, it is basically equivalent to a stall condition - So the current will be very high until the motor starts turning. With a light load, that might be only a couple milliseconds. With a heavy load, it could take long enough to cause an overload.
Running on a smooth surface is generally an easy load. Unless you happen to run into a wall or other obstacle. On a slippery surface with hard plastic wheels, they will just spin. But if you have wheels with good traction, they may stall.

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Re: Arduino Motor Shield for Tetrix motors

by weiliu on Sun Jul 01, 2018 7:13 am

*********************************************************************************
(a) You can use multiple DRB8871's. You will need 2 GPIO pins with PWM capability to control each one. (On an Arduino UNO, the PWM pins are 3, 5, 6, 9, 10, and 11)
(b) Overloads are hard to predict.
*********************************************************************************

Very good to know . But can you provide any guide or example on how to do this, whatever from adfruit or any other resources?

weiliu
 
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Re: Arduino Motor Shield for Tetrix motors

by adafruit_support_bill on Sun Jul 01, 2018 7:35 am


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Re: Arduino Motor Shield for Tetrix motors

by weiliu on Tue Jul 03, 2018 8:27 am

*********************************************************************************
(a) You can use multiple DRB8871's. You will need 2 GPIO pins with PWM capability to control each one. (On an Arduino UNO, the PWM pins are 3, 5, 6, 9, 10, and 11)
(b) Overloads are hard to predict.
*********************************************************************************

(1) What does the GPIO stand for? is it pin on Arduino or DRB8871?

(2) Also we might use new Tetrix motor (https://www.tetrixrobotics.com/TETRIX-M ... th-Encoder), which has higher torque and higher stall currernt ( close to 9A according to tech spec.), Since you said DRB8871 has limiting of only 3A, does that mean we can not use it for this new motor? If that is the case, what else would you recommend (so we can use Arduino to control the motors) ?

weiliu
 
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Re: Arduino Motor Shield for Tetrix motors

by adafruit_support_bill on Tue Jul 03, 2018 8:36 am

1) "GPIO" means General Purpose I/O. The digital and analog i/o pins on the Arduino are all GPIO pins.

2) You can use the new motors with the DRV8871. Stall current is the 'worst case' current draw. It is not a normal operating condition.

The normal operating current for DC motors is much lower than the stall current. Current limiting by the driver helps to protect both the motor and the driver from overheating if the motor does stall.

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Re: Arduino Motor Shield for Tetrix motors

by weiliu on Tue Jul 03, 2018 11:15 am

Thanks for quick response.

Forgot to ask. In your tutorial for DRV8871 ( https://learn.adafruit.com/adafruit-drv ... kout/usage), it shows that DRV8871 is used with Adafruit METRO 328/ATmega328.

I do not know anything about the METRO 328. Is it the same as Arduino UNo? In order to use the DRV8871, do we have to buy a METRO 328 or we can simply use a regular Arduino UNO?

weiliu
 
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Please be positive and constructive with your questions and comments.