64
Programmable I/O Lines
TM8000 3DK Hardware Developer’s Kit
Application Manual
September 2003
© Tait Electronics Ltd
3.2
Digital Output Lines
This section describes the general design principles for use of the
programmable I/O lines configured as outputs, and the output signals which
can be set for them.
Available Output
Lines
The following lines are available to be used as outputs:
For details on the connector pin-outs and electrical characteristics of these
lines refer to
“Description of the Radio Interfaces” on page 15
Compatibility
describes the compatibility of the output lines with common
industry logic standards:
Table 3.4
Digital output lines
Signals
Connector
Direction
AUX_GPIO4…7
auxiliary connector
input or output
IOP_GPIO1…7
internal options connector input or output
CH_GPIO1
MIC_GPIO1
a
(TM8115)
PRG_GPIO1
(TM8105)
a. CH_GPIO1 of the control-head connector is the same signal as MIC_GPIO1 of the
microphone connector (TM8115) and PRG_GPIO1 of the programming connector
(TM8105).
control-head connector
microphone connector
programming connector
input or output
Table 3.5
Digital output lines - compatibility
Output line
Logic standard output compatibility
3.3V CMOS
5V CMOS
5V TTL
RS-232
a
a. While the output levels do not comply with the RS-232 standard, almost all modern
RS-232 level conversion devices are 3.3V/5V CMOS or TTL level-compatible. There-
fore, it usually possible to drive modern external RS-232 devices directly without level
conversion if the length of the connection cable is <3m.
AUX_GPIO4…7
Yes
Yes
b
b. Yes, provided internal pullups to 5V are selected.
Yes
No
AUX_TXD
Yes
No
Yes
No
IOP_GPIO1…7
Yes
No
c
c. These outputs can be made 5V CMOS-compatible using a 3.3k
Ω
pullup resistor to
5V that is provided by the device being driven.
Yes
No
IOP_TXD
Yes
No
Yes
No
CH_TXD
MIC_TXD
PRG_TXD
Yes
No
Yes
No
CH_GPIO1
MIC_GPIO1
Yes
No
Yes
No