Name
DDR -- set a I/O port's data direction register
Synopsis
#include <port.h>
void DDR(port, value);
Description
This function determines the data direction of a port: whether the port pins are outputs or inputs. The ports are
defined in the device header. Use one of the Input/Output definitions, described below, to specify the
value parameter.
Input and output direction symbols
port.h includes definitions for each possible state of a data direction register. In these
definitions, I stands for input and O stands for output. These definitions
conveniently resolve the question of which state (zero or one) stands for input or output.