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Motor Shield Choice


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6 replies to this topic

#1 pxl357

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Posted 20 August 2011 - 02:08 AM

Hello Netduino Folks ! I'm starting a netduino project and need some advices in term of shield choice. I'm working on a 2wheels robot based on this chassis http://www.bizoner.c...letdsoa8onj5hm0 The chassis is driven by 2 motors so i bough a ardumoto shield in order to drive them but it seems not ideal as i have to actually tweak the shield ( and disable 2 pins i will need ) to make it work. I was wondering if anyone know which is the best motor shield choice for the netduino plus wich work directly out of the box. Thanks ! Pxl

#2 pxl357

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Posted 21 August 2011 - 04:39 AM

Ok after a few investigation on the forum and website , i think this one should work without any "tricks" : http://www.dfrobot.c...9&product_id=59 It's it's use the PWM which match with the netduino. Anybody have experience with it and can eventually be gentle enough to confirm it's actually works ? Thanks ! PXl

#3 Stefan

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Posted 21 August 2011 - 07:15 AM

Ok after a few investigation on the forum and website , i think this one should work without any "tricks" : http://www.dfrobot.c...9&product_id=59

Yep, works great! I got it and wrote some code for it as well:
https://stefan.co/ne...rshield-driver/
"Fact that I'm a moderator doesn't make me an expert in things." Stefan, the eternal newb!
My .NETMF projects: .NETMF Toolbox / Gadgeteer Light / Some PCB designs

#4 netdontknow

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Posted 11 September 2011 - 02:37 AM

Hello I am not an electronic guy by any mean, so sorry in advance for dump question. I have a DRrobot Motor shield that uses L293B chip, Looks like this one: http://www.dfrobot.c...9&product_id=59 I have shield sits on top of my Netduino Plus. I powered netduino plus with 4.5V battery pack. I could not get the motor running at all. do you know what specific about this driver that makes it not compatible with an L293B? -Thanks!

#5 Paul Newton

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Posted 14 November 2011 - 01:23 PM

I've just checked that this board does have compatible PWM inputs (digital 5 and 6) so looks like it should be plug and play. I am assuming that you have powered the netduino before using this 4.5V power pack and it worked without the motor driver shield. My gut feeling is that you have not got enough voltage to power the netduino, and motor driver board with motors. The netduino normally uses 5V on the USB connector or 7.5V to 12V on the Vin connector. Also the data sheet for the L293B chip (http://www.datasheet...ics/mXurruu.pdf) shows 4.5V is the minimum voltage for its logic supply. I think it is likely that when the motors are turned on the 4.5V battery voltage dips and it is just not enough to keep everything running. I see that the board has LEDs on the motor outputs, if they work when the motors are not connected - then I think I am probably correct. If so try 9V on Vin. Don't give up. I had great "fun" getting a different motor shield to work - it also needed a higher voltage. Paul

#6 seeker

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Posted 12 January 2012 - 02:04 AM

I'm trying to do something similar to the OP, I'm trying to drive 3 stepper motors (~3A each). And most of these netduino/arduino shields say they can drive 1-2A. Ardumoto (http://www.sparkfun.com/products/9815) can drive 2 motors of 2A each, does that mean I could somehow join the channels and run one 3A? I? know if this works, I would need 3 such shields, but at least the circuits will be pluggable, as opposed to buying a separate driver circuit, which would need ugly connections Also does anyone have experience with driving bipolar (4-wires) motors with any of these shields? TIA

#7 Paul Newton

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Posted 12 January 2012 - 05:53 PM

I'm trying to do something similar to the OP, I'm trying to drive 3 stepper motors (~3A each). And most of these netduino/arduino shields say they can drive 1-2A. Ardumoto (http://www.sparkfun.com/products/9815) can drive 2 motors of 2A each, does that mean I could somehow join the channels and run one 3A? I? know if this works, I would need 3 such shields, but at least the circuits will be pluggable, as opposed to buying a separate driver circuit, which would need ugly connections

Also does anyone have experience with driving bipolar (4-wires) motors with any of these shields?

TIA


Hi seeker,

I have used the Ardumoto shield to drive normal motors.

The biggest issues I had were the PWM pins being in the wrong place and getting the voltage supply to the shield high enough and separate from the Netduino supply.

Couple of questions:
  • When you say the stepper motors have four wires, do you mean they have two coils, each coil having a pair of wires, or are there four coils with a common ground (fifth wire)?
  • When you say the stepper motors are 3Amp, is that 3Amps per coil, or 3Amps total (1.5Amps per coil)?
If the motors do have two coils,

then that matches the bipolar stepper motor example in Figure 10 page 7 of the L293B datasheet.
Each coil is like a normal motor.
In this case each "PWM" input to the Ardumoto could be driven by a normal output line (output does not have to be PWM) to energise a coil, and each direction line (another normal output) would determine which polarity the coil is. Using one Ardumoto would allow a single two coil stepper motor to be driven.

If each coil is less than 2 Amps

It would be OK for each channel of the Ardumoto could be used to drive one coil of the stepper motor.


The data sheet does show combining the outputs of the L293 to give higher currents. So you could do this if you needed to, but that would mean one Ardumoto shield per coil. Also if you make a mistake wiring it up - there will be smoke!.

Think about how you are going to route the outputs from the Netduino to the shields, the Ardumoto has no way to remap the pins when stacked.

Paul




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