GPIO and Serial IO

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Dear all,

A very basic question, i guess ...

what are the differences between serial IO and GPIO (General Purposes) IO ?




Re: GPIO and Serial IO
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GPIO generally means individually toggled I/O lines. The classic is a 8-bit I/O
port where you can control the 8 bits of the port.

Serial I/O implies that only 1 bit is controlled. The classic is an 8-bit I/O
port where  the bits loaded into the port and put into a shift register which
then shifts the data out on one I/O line. Data coming in on the line (or
another) does the opposite - the data on the I/O line is clocked into the shift
register which can then be read from the 8-bit I/O port.

You can implement serial I/O using GPIO by toggling the bits via a program.

Re: GPIO and Serial IO

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The other normal difference is the signal levels on the pins. A GPIO
port will usually be TTL or CMOS levels, while a serial port has
RS-232 or 422 drivers. But, I have seen a full serial I/O port
implemented in software on a GPIO port. Two pins for data, the rest
for modem control lines. There were multiple drivers and receivers on
each line, so it could be used either way.

Bob McConnell

Re: GPIO and Serial IO

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Serial I/O is not just RS232  it is all formats that send 1 bit at a time.
I2C, USB, SMBus,  DQ, MSIO, 1 wire, ect.
They fall into 2 groups synchronous (clk and data) and  asynchronous (data line

GPIO on a cpu are usually  the non special purpose pins.  The are can be used to
read from or write to the out side word (outside the CPU anyway).  The can be
for parallel, bit banged serial, or individual control pins.

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