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Topic: shield fitting & connection (Read 929 times) previous topic - next topic

magnethead794

This is probably a dumb question....

Do all arduino shields follow a universal fitment? I want to get the Mega 2650, but all of the shields look significantly smaller, to fit the Uno. Will the shields work on the Mega as well?

Also, what is the best way to connect wires to the Arduino in a semi-permanent installation, other than just shoving them in the holes and securing with electrical tape?
KF5RVR

MarkT

The shield footprint is the same for Arduino and Arduino Mega.  However the mega has many more pins available that most shields can't use.

There is an issue with the hardware SPI pins being different on the Mega, however some shields use the ICSP header to connect to SPI which is the same on Arduino and Mega.
(Actually that's not strictly true as the ICSP header lacks the SS line, but that usually doesn't matter for SPI in Arduino-as-master mode).

So if you are using SPI on the shield its worth looking out for this.

The best semi-permanent way is to use a prototyping shield which allows arbitrary connection to any of the pins and can just be plugged in a shield-stack - there are various prototyping shields, some have screw terminals for instance.
[ I won't respond to messages, use the forum please ]

magnethead794

I'm not quite positive what ICSP and SPI mean (newbie still obviously, since i dont have a board yet). But with a board like the Mega, I don't plan on doing master/slaving and the most I plan on for module-shields is bluetooth. A majority of what I intend to do starts with getting RC radio PPM's for inputs, and multi-scaling the 5 inputs to 10 outputs, using the landing gear switch as a "mode" switch.

IE, I'm wanting to make a tracked amphibious cargo vehicle, so landing gear off would be land mode, and on would be water mode, where helicopter throttle would be throttle in both modes, but in water, left/right would turn the water jet, whereas on land it will apply proportionation to the left/right track motors. since I'll be using a water jet, land mode will let the track motors turn backwards, but in water mode, it will lower the reversing flap and spin the motor at the positive magnitude of the stick position. That frees up the entire right side 2 axis' for auxilary operations. Light sensors will activate driving lights, starboard/port lighting will come on automatically in water mode, and that's all I can think of right now.
KF5RVR

MarkT

The ICSP 6-pin header is marked "ICSP" on the board.  It carries 3 SPI signals (SCK/MISO/MOSI) as well as the supply rails and RESET.  Both the Arduino and Mega have it in the same place and it connects to the correct pins on the microcontroller.

SPI - its a serial interface that many chips and sensors use, 2 data lines 1 clock form a bus and a chip-select pin is needed per device.  If a shield and its associated library uses hardware SPI then you will need to know about this, otherwise no issue.
[ I won't respond to messages, use the forum please ]

magnethead794

Like i said, the most I intend for shields is a bluetooth module, in the forseeable future. Who knows what I might come across later in time that I might want. I just wanted to make sure that all shields for the Uno will work for the Mega.
KF5RVR

CrossRoads

Looks like Bluetooth modules plug in to the serial pins, no SPI/I2C pins used.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

magnethead794

#6
Sep 16, 2011, 06:15 am Last Edit: Sep 16, 2011, 06:21 am by magnethead794 Reason: 1
All of the prototype boards I see are solder- Where would I be able to find these screw-terminal units that are spoken of? Thanks.

Especially any that will work with all the pins of the 2560.

Here is the Uno version... http://www.robotshop.com/dfrobot-proto-screw-shield-assembled.html
KF5RVR

CrossRoads

This might be what you had in mind.
Search digikey:
phoenix
wire to board
0.1" pitch

for example:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=277-1279-ND
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

magnethead794

I found the version for the Uno, posted above. But for the Mega's other pins, am I left to just shoving wire in and hoping it stays with tape?
KF5RVR

CrossRoads

This is another option:
http://www.pololu.com/catalog/category/74
These male terminated wires plug in pretty securely into the shields. You can get male-male, male-female, do what you need on the other end.
Slip them into housings
http://www.pololu.com/catalog/product/1907 1x1, 1x2, 1x3, 2x4, 2x8,  lot of sizes available.
Then you've a neat terminated bunch that is all aligned. Maybe a spot of hot glue across the housing/shield joint to hold it together of needed. Or a cable tie around the board. Whatever you need.
I bought several bag of 50-packs of wires & a couple bags of the 1x1 thru 1x6 housings, that stuff has been one of the handiest things I ever purchased for projects, I have gotten a lot of use out of them, and need to get some more housings now too as I am running low.
The female terminations will also go over 0.025" square posts, so I have cables that I slide onto wirewrap posts too use as male terminations on boards.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

Maybe this
http://www.robotshop.com/arduino-proto-shield-kit-mega-4.html
in combination with the phoenix connectors.
Square pins going down to plug in the shield, screw terminals in the next holes over.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

magnethead794

#11
Sep 16, 2011, 07:10 am Last Edit: Sep 16, 2011, 07:13 am by magnethead794 Reason: 1

This is another option:
http://www.pololu.com/catalog/category/74
These male terminated wires plug in pretty securely into the shields. You can get male-male, male-female, do what you need on the other end.
Slip them into housings
http://www.pololu.com/catalog/product/1907 1x1, 1x2, 1x3, 2x4, 2x8,  lot of sizes available.
Then you've a neat terminated bunch that is all aligned. Maybe a spot of hot glue across the housing/shield joint to hold it together of needed. Or a cable tie around the board. Whatever you need.
I bought several bag of 50-packs of wires & a couple bags of the 1x1 thru 1x6 housings, that stuff has been one of the handiest things I ever purchased for projects, I have gotten a lot of use out of them, and need to get some more housings now too as I am running low.
The female terminations will also go over 0.025" square posts, so I have cables that I slide onto wirewrap posts too use as male terminations on boards.



I like! For a Mega, I'd be needing a 2x16, 5x (1x8)'s, and a 1x6. Not bad!
KF5RVR

CrossRoads

Order some extras, then you can move your mega between projects too.
Pololu will also send free back issues of Elektor magazine,
enter the coupon codes when you order:
ELEKTOR0911
try older ones too:
ELEKTOR0811
ELEKTOR0711
ELEKTOR0611
ELEKTOR0511
ELEKTOR0411
ELEKTOR0311
ELEKTOR0111
ELEKTOR1210
ELEKTOR1110
ELEKTOR1010
ELEKTOR0910
ELEKTOR0810
ELEKTOR0710
ELEKTOR0610
ELEKTOR0510
ELEKTOR0410
ELEKTOR0410
ELEKTOR0210
ELEKTOR0110
ELEKTOR1209
etc.

You only pay for the shipping on them. Some great reading there.
I was able to get most of Jul/Aug 09 thru Nov 2010 with  past orders.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

Just ordered 2 servo's to play with, 10 more issues of Elektor magazines (2011's, and a couple of 2010's), packages of crimp housings in a bunch of sizes (including 2x3 for ISCP connectors), and 1x6 & 1x8 female headers for some other boards.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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