Zuzebox writes in about Raspberry Pi’s GPIO pins:
There seems to be some misunderstanding about how h/w hackable to RPi is?
It’s got 17 i/o lines which is only 3 less than an Arduino which has 20 i/o. It’s got GPIO, UART, SPI, I2C and a single PWM. The only thing it lacks is analog i/o. Check out the stuff I’ve built for the Rpi on my blog
Via the forum.