Pages: [1]   Go Down
Author Topic: Design considerations for shields etc.  (Read 971 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 26
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi,
Yesterday I purchased some additional shields for use with my Arduino Uno and Mega 2560. Even in this very short time playing with them unpowered I've made some observations about general sheild design. I'm hoping this has already been discussed and someone can refer me to it. My  own selection of search words generate too many hits.
First, why do the basic microprossessor boards from all vendors that I've seen not utilize headers that have pins sticking out the bottom so that additional shields can be plugged in under the microprocessor board? I presume this would be easy for individuals to fix by just desoldering the existing headers and replace them with ones that look more like daughter shieds. Has anyone done this to microcontroller shields? You can use the old desoldered headers with these pins now sticking out to protect (physical and electronically) by just puching them over the pins. This brings up another need. Where can I get a breadboard with pin spacing specifically designed for an Arduino shield? The breadboard shold then mate with more standard spacing of regular breadboars. You may only need one of these, but it would be handy.
More about spacing. It would be very convenient if there were a row of holes outside of the vertical headers that were elecricly connected to the header pin beside it. This would give access to all these pins for test equipment whithout the need of a breadboard. It would definately make things easier to test once the electronics are deployed.
Finally, and this is my biggest gripe, Why are the headers often shorter (less tall) than the some of the components on the shields? This prevens the shields from sitting parallel to one another when stacked together. Along with that it then shows where components, being too tall, bump against each other and the stack of PCBs starts to tilt. Such shields should also never be too large, thereby preventing access to header pins below. Why not use taller headers or provide additional headers to plug into one another to prevent the tilt?
Lastly, has anyone come up with a way to accommodate what I like to call human input and output shields i.e. joystick shield and output shields LCD shields etc. A stack of shields can only have one "top", say for an output shield that humans want to see in real time, and at least one input sheld for use with hands. Perhaps some sort of three dimensional cube arrangement where shields can be plugged into all six sides of a cube and be electronically connected to each other. This wouuld avoid the tangle of wires currently necessary.
Sorry for the long post, but I had to ask. :-) 
Logged

0
Offline Offline
Edison Member
*
Karma: 7
Posts: 1411
Arduino rocks
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
why do the basic microprossessor boards from all vendors that I've seen not utilize headers that have pins sticking out the bottom so that additional shields can be plugged in under the microprocessor board?
You don't want to plug an LCD or a LED matrix shield "under the microprocessor board", do you?

Quote
Why are the headers often shorter (less tall) than the some of the components on the shields?
That's rarely the case. The highest component I saw was the Ethernet connector. You would need to adapt your shield to fit those boards (or pick one that fits).
Logged

nr Bundaberg, Australia
Offline Offline
Tesla Member
***
Karma: 121
Posts: 8439
Scattered showers my arse -- Noah, 2348BC.
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
why do the basic microprossessor boards from all vendors that I've seen not utilize headers that have pins sticking out the bottom
Mostly I suspect because they would be vulnerable to mechanical damage and subject to shorting out on everything you place the board on. That said a board I've designed has the headers "upside down" with the socket part under the board. That allows stacking in both directions and also allows for different stacking heights to clear tall components, something you can't do with the socket strips in the normal orientation.

Quote
easy for individuals to fix by just desoldering the existing headers
Ever tried desoldering a large header, not easy unless you destroy it.

Quote
Where can I get a breadboard with pin spacing specifically designed for an Arduino shield?
You won't, mostly because they stuffed up the design and the headers are not on a .1" pitch.

Quote
It would be very convenient if there were a row of holes outside of the vertical headers that were elecricly connected to the header pin beside it.
Very true, and I think I have see a board or two with that feature.

Quote
A stack of shields can only have one "top",
True, the only practical way I can see is that the top shield has to do all the HMI stuff.

Quote
Perhaps some sort of three dimensional cube arrangement
Not quite that but the Tower system

http://www.freescale.com/webapp/sps/site/homepage.jsp?code=TOWER_HOME&fsrch=1&sr=3

has a display module that plugs onto the side

http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=TWR-LCD&fsrch=1&sr=17

______
Rob

« Last Edit: May 13, 2012, 09:39:58 am by Graynomad » Logged

Rob Gray aka the GRAYnomad www.robgray.com

Offline Offline
Newbie
*
Karma: 0
Posts: 26
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
why do the basic microprossessor boards from all vendors that I've seen not utilize headers that have pins sticking out the bottom so that additional shields can be plugged in under the microprocessor board?
You don't want to plug an LCD or a LED matrix shield "under the microprocessor board", do you?

Quote
Why are the headers often shorter (less tall) than the some of the components on the shields?
That's rarely the case. The highest component I saw was the Ethernet connector. You would need to adapt your shield to fit those boards (or pick one that fits).
I've overcome the problem of component height exceeding the header height by simply by stacking a second set of headers into the board with the "too tall" componets. Then use some hot glue to make it semi permanent. The pins still all line up, there is no permanent HW mod required and can be undone at any time; and the next shield to be plugged in (above) the modded one will sit parallel to it, no tilting. I still have to try my idea of desoldering the existing headers from the Arduing micro- controller board and replace it with headers that have pins that could plug into shields below that card. The original headers will be used to protect the protruding pins when not i use. I just have to seal (insulate) the pins from protruding onto any surface and cause problems. Some more hot glue may be in order to accomplish that. Sometimes the problem is asking the question in just the right way. Then the answer then becomes obvious. Thanks for the replies I've gotten on this so far. It's been gratifying to realize that others have encountered the same issues.   
Logged

0
Offline Offline
Edison Member
*
Karma: 7
Posts: 1411
Arduino rocks
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

There are Arduino clones like this one
http://www.sparkfun.com/products/10915
that come with no headers soldered. They may suit your needs better.
Also, you can buy an Arduino clone as a kit (e.g. Freeduino, Wiseduino etc) and install the headers as you wish.
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 26
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
Where can I get a breadboard with pin spacing specifically designed for an Arduino shield?
You won't, mostly because they stuffed up the design and the headers are not on a .1" pitch.
[/quote]
Quote
It would be very convenient if there were a row of holes outside of the vertical headers that were elecricly connected to the header pin beside it.
Very true, and I think I have see a board or two with that feature.
[/quote]
I think I just found the answer to my question with regard to pin spacing to allow use with standard breadboards. Have a look at this product, seems to just what I was wishing for...
http://www.sparkfun.com/products/9374
You would only need a few of these offset hearders provided you did not use them permanently. At the price, It's not a problem either way.
Things are looking up!
Logged

Global Moderator
Netherlands
Offline Offline
Shannon Member
*****
Karma: 168
Posts: 12430
In theory there is no difference between theory and practice, however in practice there are many...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
Where can I get a breadboard with pin spacing specifically designed for an Arduino shield?

IIRC I have seen a shield for just that ... but where ..???

here - http://www.instructables.com/id/Large-Arduino-Prototyping-Shield/ -

or were it specialized headerpins
Logged

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 437
Posts: 23718
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Gravitech has a nice shield - with uSd card slot built in as well.
http://www.gravitech.us/microsdshield.html
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Dubuque, Iowa, USA
Offline Offline
Edison Member
*
Karma: 29
Posts: 2244
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Terry sells them at the cheapest price I've seen: http://arduino-direct.com/sunshop/index.php?l=product_detail&p=96 ($2.50)

Hi Terry! Send me free stuff!


If you're obsessive compulsive and want a layout that meets your personal criteria then you can use a service like iteadstudio/seeedstudio and design your own boards. The price is $25/10 boards if you squeeze the pins to the edges of the board on a 10cm x 10cm board.
Logged

Pages: [1]   Go Up
Jump to: