32 TA2922 Universal Line Interface Service Manual
© Tait Electronics Limited March 2010
connection to a open collector output from third-party equipment. The maximum
voltage on this line should not exceed 5V to prevent damage to the input transistor.
QEXT GPIO3
■ Signal direction: bidirectional
■ Signal level: 3.3VDC max
■ Signal impedance: 470 ohms
General purpose programmable digital input/output line. The action of this line is
defined by the radio programmable digital I/O section of the radio programming
application. See “Programmable I/O form, Digital tab” on page 39.
The radio programming defines if the signal is an input or an output while the
TA2922 options board transparently passes the digital signal between the radio
internal options port and the external connector.
The digital signal travels through the microcontroller on the TA2922 board which
scans and updates I/O lines once every 10ms, so this latency time should be
allowed for in timing calculations. The maximum voltage applied to this line
should not exceed 3.3VDC.
REXT GPIO4
■ Signal direction: bidirectional
■ Signal level: 3.3VDC max
■ Signal impedance: 470 ohms
Option board disable and general purpose programmable digital input/output line.
Note When the radio IOP_GPIO4 line is set as an output from the radio and
the output becomes active (low), all audio and keying functions of the
TA2922 board are disabled.
In the disabled state, the state of IOP_GPIO4 is still passed through to the external
output section. All other GPIO operations are not affected when the TA2922 is in
disabled state. The action of this line is defined by the radio programmable digital
I/O section of the radio programming application. See “Programmable I/O form,
Digital tab” on page 39.
The radio programming defines if the signal is an input or an output while the
TA2922 options board transparently passes the digital signal between the radio
internal options port and the external connector. The digital signal travels through
the microcontroller on the TA2922 board which scans and updates I/O lines once
every 10ms, so this latency time should be allowed for in timing calculations. The
maximum voltage applied to this line should not exceed 3.3VDC.
SEXT GPIO5
■ Signal direction: bidirectional
■ Signal level: 3.3VDC max
■ Signal impedance: 470 ohms
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