I got my self a Sparkfun RTC breakeout board, contrary to their wiring example it only seem to work with SDA wired to A4 and SCL to A5, is it possible to wire it opposit? With A1 and A2 set for power and ground it would make it possible to plug the RTC breakeout straight into the pins.
I understand i2c is a form of bus and that components have and addresse on it, but i dont understand the phyisical wiring to this bus.
For now I moved it in on the board and crossed the wires.
-- Regards Andreas
Sorry, I2C is a hardware feature bound to those pins. A5 = SCL, A4 = SDA.
Rob
Thank you for the conclusive answer I needed to move on in my mind 
A bound hardware feature in the arduino i guess? Just curious for future reference, example being expanding the bus to more than one component or using other I2C components.
-- Regards Andreas
A bound hardware feature in the arduino i guess?
You can blame Atmel for this, the ATmega328 chip used by most Arduinos has certain function hard wired to certain pins, most notably SPI, I2C, UART, Timers and ADC.
This is normal for microcontrollers.
expanding the bus to more than one component or using other I2C components.
??
Rob
The later was just meant as examples of why a little deeper knowledge would be appreciated.
for expanding the bus to two or more components or using other I2C components its important to know if the setup is dictated by the board (MC) or the component, soo i know how to do the wiring.
Again thanks for you reply it was very helpful.
-- Regards Andreas