What can you connect to GPIO?

[Edward78]

Not wanting specifics just wanting to know if you can connect things like Sata controllers???

[Theguywhobea]

GPIO on what? Like a Raspberry Pi? The pinout for the GPIO on those is pretty well documented, just google it.

[An angry badger]

Know you didn't want specifics but it is my understanding that SATA is not supported over GPIO

[HarryNyquist]

It's in the name: General Purpose Input/Output. By default they're used for nothing, and the user can program them to do almost anything, limited by the hardware by which they are backed. In the case of a raspberry pi, for instance, there's no SATA controller or access to PCI Express in order to make SATA work properly. You'd be better off with a SATA-to-USB drive dock for that purpose.

[Mira Yurizaki]

GPIO, as the name implies, is an input or output line. It can only have two states: on or off (for the electrically inclined, it's usually 0V to 3.3V or 5V). If configured as an output, the software running on the CPU has to tell it when to toggle it on or off. If configured as an input line, the software running on the CPU has to check it. In other words, it's a software controlled I/O line.

 

This is opposed to say a hardware UART, or a serial data interface. The most software does with it is configure the parameters and feed it data. The hardware in the UART will take care of transmitting the data or receiving the data (the software still has to read the data though).

 

You can connect anything to a GPIO line as long as you're aware of the following:

• You have enough GPIO lines the interface needs (SATA needs at least 5 lines)
• The GPIO lines can output or receive the correct voltage level.
• You understand the protocol of the interface
• The software can run fast enough to "bit bang" the signal. For more info on bit banging, see https://en.wikipedia.org/wiki/Bit_banging

But really, you should only use GPIO lines for simple I/O devices like LED lights or switches. You might be able to use them as a low speed UART/SPI/I2C bus, but if your CPU is too slow, then it won't work.

Edited January 15, 2018 by M.Yurizaki