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Obstacle Avoidance Robot with SeeedStudio Motor Shield V2

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#1 bradygaster

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Posted 06 December 2014 - 06:30 PM

I've completed preliminary work on the first stage of a robot I've been building. It is my first, a basic autonomous bot using a Parallax Ping sensor and a SeeedStudio Motor Shield V2. I'd not seen any articles on using the motor shield, so I hand-crafted a driver for it. I'll be posting the code into this forum once I get it completed and have some good pictures and video, and I'm planning on adding a few ideas to this as I go. 

 

There's one problem, and for all you robot experts out there this should be basic. So please, help. :) I'm so close!

 

I'm blocked, however, by one very basic thing. The configuration is pretty simple. 

  1. Netduino 2 atop robot chassis
  2. Seeed shield atop Netduino
  3. Connections to breadboard, into which Ping sensor is plugged

Here's the problem, with which I'd love some guidance. When I put batteries into the battery pack and it powers up, the wheels spin, but the Ping doesn't turn on. When I plug in to USB, the Ping turns on. It seems like the power isn't getting transmitted to the breadboard from the 5V jumper on the shield. There's probably a dirt-simple fix for this, any help would be much appreciated. 

 

There's a few pictures of the bot in the attachment, as well as the motor driver code. Once the whole thing is complete I'll definitely share more the whole project (probably via GitHub) and blog about it. 

 

Disclaimer: I asked my 6-year-old son what the name should be and he chose the name, which matches the name of a big hero character. I'll change it before it goes out, wouldn't want to violate copyrights!

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#2 Mike L

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Posted 06 December 2014 - 09:46 PM

Hi Brady,

The bot looks cool. Do you have a Fritzing drawing of your wiring?

http://wiki.netduino...ng-diagram.ashx



#3 Paul Newton

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Posted 07 December 2014 - 09:14 AM

Great project so far!

 

Mike is on the right track - we will need a wiring diagram to help understand what is wrong with the power.

The photos don't quite allow us to see the wiring well enough to understand what is connected where.

 

I use a mixture of fritzing and paint - both are free. Which one I select for a particular job depends on whether I think I will change the diagram a lot (in which case fritzing is better).

 

Have Fun - Paul



#4 Mike L

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Posted 07 December 2014 - 01:03 PM

It is possible that the combination of running the motors and the ping sensor on the same supply is causing the issue.  Typically I try to have a separate power source for the motors because they have a tendency to generate a lot of noise that can interfere with other logic or sensors.

 

Here is a couple troubleshooting things you can do:

  1. Double check your power source for your design.  Typically hbridge motor drivers allow for a dual source so that you can separate the motor power from the logic power.  Maybe you only have the motor power being supplied and the logic power is being supplied when you plug in the USB.
  2. Comment out the code that turns on the motors.  On power up does the ping sensor seem to be working while the motors are no longer running?
  3. If the ping sensor still doesn't work make sure you delay some on your start up code before you start doing the ping.
  4. If you still don't have ping on power up then try removing the Motor Shield.


#5 bradygaster

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Posted 08 December 2014 - 09:05 AM

I couldn't find a fritznig model for the Seeed motor driver, so that's implied as atop this one. In this you'll see the Netduino and how it drives the ping. The Netduino does get power from the motor driver, but it doesn't drive the ping sensor at all. Seems like re-routing some additional channels (VIN, maybe?) to the breadboard and back again might make things work better for the Netduino?

 

I also attached the best photo I could find of the shield for your review. The Netduino runs from 5V/GND/Digital to the Ping. Works just fine so long as the Netduino is plugged into USB. 

 

Thanks for your review and assistance!

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