A better way?
Moderators: adafruit_support_bill, adafruit

A better way?

by simon99 on Fri Sep 20, 2013 4:01 pm

Hi,

I am redesigning a second prototype of my Aduino / Android device, with the view to making it more robust by the use of a shield and some soldering, instead of the current wires, glue, gravity and prayer approach.

The device has several components. At the heart it is a remote Android phone with a server app I wrote. The app receives remote commands from another Android phone that has the client side app. With the app, I can tell the remote phone to pan, tilt, zoom, take photos and email them to me. I use it on my farm to check on things when I am overseas. I have several of these systems mounted around the farm. The remote phone is connected to an Arduino ADK board. The board powers the phone through USB accessory mode and the phone commands the board. The board is also connected to servos, which control a pan/tilt system that holds the remote phone. The entire unit is housed in a weatherproof dome, hooked up to a sealed led acid battery and a solar panel. It sits up atop a hill on a power pole I sank, to keep it from blowing away when exposed to the howling elements coming off the Southern Ocean.

The power from the lead acid battery comes in a 12V via a charge controller, but the 5V from the board which could power the servos has insufficient current, so I also use a 12V -> 5V DC/DC converter. In addition, to eliminate power consumption of the servos when idle (Which is 99.99% of the time), I drop a pin low on the Arduino after the servos have repositioned, which tells the DC/DC converter to cut power to the servos. As Android phones are very low consumers of power, the whole system uses a trickle of power when not in use.

I have attached some photos.

1.jpg
1.jpg (75.06 KiB) Viewed 192 times
2.jpg
2.jpg (65.54 KiB) Viewed 192 times
3.jpg
3.jpg (95.66 KiB) Viewed 192 times


What I would like to do to improve the design is add a shield to the ADK board which provides stable, strong 5V to the servos yet with which I have the ability to totally disconnect power to the servos. Can the servo shield do this? My current setup uses a breadboard and a second board just held in with tape and I am not happy with the quality.
simon99
 
Posts: 4
Joined: Fri Sep 20, 2013 3:26 pm

Re: A better way?

by simon99 on Fri Sep 20, 2013 4:03 pm

6.jpg
6.jpg (53.21 KiB) Viewed 189 times
4.png
4.png (56.62 KiB) Viewed 189 times
4.png
4.png (56.62 KiB) Viewed 189 times
More photos:
Attachments
5.png
5.png (48.43 KiB) Viewed 189 times
Last edited by simon99 on Fri Sep 20, 2013 4:09 pm, edited 1 time in total.
simon99
 
Posts: 4
Joined: Fri Sep 20, 2013 3:26 pm

Re: A better way?

by simon99 on Fri Sep 20, 2013 4:04 pm

Ok, the important one at the bottom now:

7.jpg
7.jpg (52 KiB) Viewed 191 times
8.jpg
8.jpg (105.23 KiB) Viewed 191 times
simon99
 
Posts: 4
Joined: Fri Sep 20, 2013 3:26 pm

Re: A better way?

by adafruit_support_bill on Fri Sep 20, 2013 4:29 pm

provides stable, strong 5V to the servos yet with which I have the ability to totally disconnect power to the servos. Can the servo shield do this?

Yes. The servo power is supplied via a separate terminal block. You can connect a dedicated servo supply to that. If you want to disconnect via program control, there are a couple of options. A powerswitch tail can be used to cut power to your servo power supply. Or you could use an N-channel power MOSFET to cut power at the board. It is a fairly simple circuit and could be soldered to the prototyping area of the shield.

http://www.adafruit.com/products/268
http://www.adafruit.com/products/355
User avatar
adafruit_support_bill
 
Posts: 31071
Joined: Sat Feb 07, 2009 10:11 am

Re: A better way?

by simon99 on Fri Sep 20, 2013 6:58 pm

Thanks.

Hmm. If the servo power is connected by a separate terminal block and I still need to add some kind of circuit, than I don't see the point of the servo shield for my purpose.

I already have the 12V -> 5V converter board separately now to both step down the power to the two servos and give me the power cut off functionality with one wire that I bring low. I don't need any more functionality. I was hoping the servo shield could do that. If not and I have to add power and the cut off anyway, I don't see how it helps.

I might just try fitting a generic shield and attaching the converter to it. It was the way the converter was attached to the breadboard that bugged me. Not very professional.
simon99
 
Posts: 4
Joined: Fri Sep 20, 2013 3:26 pm

Re: A better way?

by adafruit_support_bill on Fri Sep 20, 2013 9:49 pm

If your current circuit meets your needs functionally, then moving it to a proto-shield or wing shield would be a reasonable way to make it more robust:

http://www.adafruit.com/products/51
http://www.adafruit.com/products/196
User avatar
adafruit_support_bill
 
Posts: 31071
Joined: Sat Feb 07, 2009 10:11 am