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Topic: Arduino Uno Rev3 pinouts photo (Read 105320 times) previous topic - next topic

WizenedEE


I find that the pins on the ICSP header (on the right) are useful for grabbing an extra +5/Gnd combination if I need to power other devices (or for hooking up a multimeter or logic analyzer).


I generally use the giant USB socket for a gnd to connect my multimeter to.

opal_1970

#16
Feb 05, 2012, 10:11 pm Last Edit: Feb 06, 2012, 10:26 am by opal_1970 Reason: 1
Hey thanks alot for sharing, this is really useful.

(cool, and I am the 1970th person to view this)

pitusso

Have you already share this in the playground?
It's very useful!

sellonoid

Please pardon the somewhat off topic post....


I just bought an R3 Uno and it has the DIP processor.

Are the surface mount versions out yet, and are there any advantages to the surface mount types?

CrossRoads

Surface mount was used on Unos when DIPs where in short supply for a while.
Same die within each package.
Surface mount does allow access to two analog-input only pins, but they are not connected to any header pins on the Uno.
So really just a disadvantage when you smoke the chip by accident and need to replace it.
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.

Nick Gammon

I like the removable ones. After all, if you test new sketches every day (as I do) then you will wear it out eventually. Rather than buying a new board for $30 I can replace the processor for $5. Similarly if I do something silly and burn out an output pin.

When you are ready to go you can buy one of the surface-mounted "tiny" versions that will be physically smaller and do the same things.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

tuxduino

Thanks Nick, that photo is useful. A very good page on your site, too.

NI$HANT

"Real Men can Accomplish  Anything"

- skype : nishants5  

ਫ਼ਤੇਹ ਕਰੁਂ!

Nick Gammon

I wondered that when I was doing the picture. See this:

http://arduino.cc/forum/index.php?topic=83829.0
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

Thanks for the pictorial doc.

BTW, what is the scoop on why they the second access to A4 and A5 (SCL & SDA).  Why would they be needed twice?
Facts just don't care if you ignore them.

Nick Gammon

On the Mega SDA and SCL are in different spots. I am guessing they wanted to make it so shields could be compatible with both the Mega and the Uno if they use I2C.
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

CrossRoads

#26
Mar 27, 2012, 03:18 am Last Edit: Mar 27, 2012, 03:20 am by CrossRoads Reason: 1
paraphrasing Blazing Saddles:
"You said I2C twice."
"I like I2C."
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.

bperrybap

I actually prefer what Seeeduino and iTeeduino did for i2c on their boards by providing a separate 4 pin header.
That way everything you need is there with a simple 4 pin connector/cable and you can still
use it even when a shield is being used.

--- bill


Below is a modified photo of the Uno Rev3 board, with annotations about the extra meanings of some pins (not printed on the board):
Earlier boards are similar except that they don't have the ICSP header for programming the USB interface chip, and the extra SDA/SCL sockets for use with I2C.


Are the I2C pins on the D8-D13 header the same as the ones on A4 and A5? If so, are these in the same place as on a Mega because the A4 and A5 pins moved to D20 and D21 on the Mega and that's a pain for building a shield.

Thanks

CrossRoads

"Are the I2C pins on the D8-D13 header the same as the ones on A4 and A5?"
On Uno, Yes.

"are these in the same place as on a Mega because the A4 and A5 pins moved to D20 and D21"
No.
Mega has seperate functions pins for I2C, are not on A4/A5.
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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