Like a lot of folks we got excited when the Raspberry Pi was first announced. We couldn't wait to get our hands on our first board. When our chance came to get a Pi we also bought a prototyping board so we could connect up our own devices to the Pi. We anxiously awaited the arrival of our card. It felt like our card would never arrive.
While we were waiting, we dug deeper and found out that Raspberry is limited to 3.3V I/O and we realized that the GVS devices we already have for our Arduinos are 5V parts that would not work with our Raspberry Pi. Sure we could adapt one of the 3.3V to 5V converters out there but that sounded like a lot of work. What we really wanted was a way to allow our 5V parts to connect to the Raspberry Pi without a lot of hand wiring but we couldn't find a card out there that does the 3.3V to 5V voltage conversion that our 5V parts need.
So we designed a card to meet our needs, the Raspberry Pi-GVS..
3.3V to 5V bidirectional voltage translators on Raspberry Pi GPIO lines
(7) 5V GPIO lines on GVS connectors(2) 5V SPI interfaces (can be used as 5 GPIO lines)
(1) 5V UART interface
(1) 5V I2C interface (can be used as 2 GPIO lines)
GPIO_4 enables/disables the voltage translators
Power Supply which can power the Raspberry Pi and/or the GVS connectors