1
\$\begingroup\$

I bought an R3 Ethernet shield for my R2 Arduino Uno, but I noticed that it has a few more pins than my R2 Uno has sockets. Do I need to buy a different shield?

Arduino UNO

Arduino Ethernet Shield

\$\endgroup\$
  • 5
    \$\begingroup\$ Post links to devices and we'll be able to comment. \$\endgroup\$ – AndrejaKo Jul 20 '12 at 22:17
  • 1
    \$\begingroup\$ It's probably cheaper to buy a new r 3 arduino. The shields I've seen are more expensive than the arduino itself. \$\endgroup\$ – Chris Laplante Jul 20 '12 at 23:45
  • \$\begingroup\$ Hi, sorry for the delay. The links are link and link. Unfortunately, I think that @SimpleCoder might be right. Thank you guys for your time! \$\endgroup\$ – cjohnson318 Jul 21 '12 at 3:15
  • \$\begingroup\$ @jippie, that is terrific explanation. Thanks so much! \$\endgroup\$ – cjohnson318 Jul 23 '12 at 13:36
6
\$\begingroup\$

When I take a look at the schematic for R3,

Partial shematic Uno R3

it appears that the extra pins at the top left:

Arduino UNO R3 Arduino Ethernet Shield

carry the same signal as pin A4 (AD4/SDA) and pin A5 (AD5/SCL).

The extra two pins at the bottom left are respectively unused and attached to +5V according to the same schematic diagram. Unsure why the printing IOREF on the PCB gives other impression.

Power connector UNO R3

As a solution, you should be able to simply wire the top left two connections to the bottom right ones (A4 and A5).

A multimeter should be able to confirm my theory. The new connections on R3 have probably been introduced to allow for smaller shields still using power supply and I2C bus.

As a reference the R2 looks like this:

Arduino Uno R2

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.