Tait TM8000 Series, Руководство по применению

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40 Programmable I/O Lines TM8000 3DK Hardware Developer’s Kit Application Manual
September 2003 © Tait Electronics Ltd
Compatibility and
Tolerance
Table 3.2 describes the compatibility of the input lines with common
industry logic standards:
Input Philosophy
The digital inputs are designed to simplify the interfacing to a wide range of
signal sources, broadly encompassing directly wired switches, open-collector
transistors, opto-isolators, digital logic and direct microprocessor drive.
In many cases, the amount of interfacing circuitry can be kept to a
minimum, thus reducing design effort and keeping down both cost and
circuit board area.
Input Circuitry
Figure 3.1 shows a simplified circuit diagram of the digital input lines
(ESD protection not shown). For full circuit diagrams, refer to the PCB
Information chapter of the TM8100 Mobile Radio Service Manual or the
technical support website.
The input lines of the auxiliary connector and the control-head connector
are protected against both over-voltage and under-voltage drive via the
clipping diodes and 47k
Ω
current-limiting resistor. The input lines of the
internal options connector are only protected against minor over-voltage
conditions (refer to
“Internal Options Connector” on page 28 ).
Table 3.2 Digital input lines - compatibility and tolerance
Input line
Logic standard input compatibility and tolerance
3.3V CMOS 5V CMOS 5V TTL RS-232
AUX_GPI1 Yes Yes Yes No
a
a. Level compatible but not tolerant. Inputs can be made RS-232-tolerant by using
3.3k
Ω
series resistance inserted at the radio end.
AUX_GPI2
b
b. Hardware link LK3 not fitted.
Yes Yes Yes No
a
AUX_GPI3
c
c. Hardware link LK2 not fitted.
Yes Yes Yes No
a
AUX_GPIO4…7 Yes Yes Yes No
a
AUX_RXD Yes Yes Yes Yes
IOP_GPIO1…7 Yes Yes Yes No
a
IOP_RXD Yes Yes Yes No
a
CH_RXD
MIC_RXD
PRG_RXD Yes Yes Yes Yes
CH_GPIO1
MIC_GPIO1 Yes Yes Yes No
a