E0C6001 TECHNICAL HARDWARE
I-32
Input or output mode can be set for the four bits of I/O port
P00–P03 by writing data into I/O control register IOC.
To set the input mode, 0 is written to the I/O control regis-
ter. When an I/O port is set to input mode, its impedance
becomes high and it works as an input port. However, the
input line is pulled down when input data is read.
The output mode is set when 1 is written to the I/O control
register (IOC). When an I/O port set to output mode works
as an output port, it outputs a high signal (V
DD
) when the
port output data is 1, and a low signal (V
SS
) when the port
output data is 0.
After an initial reset, the I/O control register is set to 0, and
the I/O port enters the input mode.
The output specification during output mode (IOC = 1) of the
I/O port can be set with the mask option for either comple-
mentary output or Pch open drain output. This setting can
be performed for each bit of the I/O port. However, when
Pch open drain output has been selected, voltage in excess
of the supply voltage must not be applied to the port.
Mask option
I/O control register
and I/O mode
Содержание E0C6001
Страница 4: ...Hardware E0C6001 I Technical Hardware ...
Страница 79: ...Software E0C6001 II Technical Software ...