Calibre UK UCA93 - Manual (Page 17)

CALIBRE
Issue 1.0 Page 14
01/07/03
3.3.21. Write_IO_Pin
Function specification int Write_IO_Pin (int IONumber, int IOState)
Parameters are:int IONumber
The number of the IO pin (0 or 1) to be driven
int IOState
The required state (0 or 1) of the selected IO pin
Parameters returned int
Returns a 0 if function successful.
Returns 0x800D if the transfer timed out.
Prerequisites None
Functional description Two spare IO pins are available to drive external logic. IO0 is on PL1 pin 2 and
is an open drain driver. When driven low it can sink up to 10mA, when high it is
high impedance and cannot source current. A pullup resistor should be fitted to
the desired rail which should not exceed +5V. IO1 is on PL1 pin 3 and is a
complementary driver which can source or sink up to 10mA. Its logic levels are
fixed at 0V and +5V nominal.
3.3.22. Read_IO_Pin
Function specification int Read_IO_Pin (int IONumber)
Parameters are:int IONumber
The number of the IO pin (0 or 1) to be read
Parameters returned int
Returns the state (0 or 1) of the chosen IO pin if function successful.
Returns 0x800D if the transfer timed out.
Prerequisites None
Functional description Two spare IO pins are available which can be driven by external logic. IO0 is
on PL1 pin 2 and IO1 is on PL1 pin 3. These pins are normally high impedance
input unless specifically driven by the Write_IO_Pin function. They can be
driven high or low by external logic then read by the Read_IO_Pin function.
Normal 5V CMOS logic levels (0 < 1.5V, 1 > 3.5V) should be applied for reliable
reading.