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Topic: How to use two shields that use the same pins (Read 735 times) previous topic - next topic

easycount

Hi, I'm trying to use these shields

http://shieldlist.org/dfrobot/lcd

http://shieldlist.org/sparkfun/rfid-eval

at the same Arduino Uno but both use the same pins. How could I make this possible?

MichaelMeissner

Generally you can't (there are shield converters that convert the pins to different pins, but you then need to do major mods to the software, and if the pins use special things like I2C, SPI, PWM, etc. you may still be out of luck).

However in this case, use a LCD shield that uses I2C instead of a lot of pins like this Adafruit shield: http://www.adafruit.com/products/772.  I2C is a shared bus using 2 pins (A4/A5 on the Uno), and you can hook multiple devices to the bus.  So, the RFID shield would use multiple pins, but this shield would only use A4/A5 and allow connection to other I2C devices. 

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