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5.15 Extended I/O capabilities
Using Embedded Applications
5.15.1 LED/IO6 Capabilities
LZT 123 7589 R1A
5. SYSTEM CONNECTOR INTERFACE
The operational modes of multiplexed signals are controlled by AT
commands and also by intrinsic functions available to an embedded
The following table gives you the input impedance. These values only
apply when the ports are configured as input signals.
Parameter
Input impedance (pull-up)
I/O6 (LED) doesn't have an internal pull up. If this pin is configured as an
input, it should not be left floating.
I/O7 (TD3) has a pull down instead of a pull up.
To increase flexibility and variety of radio device peripherals, the RS232
hardware flow control shares its physical interface with the keypad
scanning interface and the extended general purpose I/O capability. This
sharing means that it is not feasible to operate all these features
concurrently, however, with care, dynamic switching from one feature to
another is possible.
When a particular I/O feature is required, the user sets the state of the
relevant I/O blocks by disabling one set before enabling others.
The radio device checks the state of the I/O when the user requests a new
function. The new function is rejected if the current function is not released
first.
Only the states of I/O1 - I/O5 are retained for the next power up. For
example, inputs remain as inputs and outputs remain as outputs. The
voltage of a defined output pin will still drop to 0 Volts in the radio device
power down state.
The LED function pin can be used as a general purpose digital I/O when
the flashing LED function is not required. However, this pin does not have
an on-board pull-up resistor. It is required that an external pull-up or pull-
down resistor be provided by the host circuitry when either not used or
when used as a digital input.
Min.
Typ.
Max.
50
100
120
Units
k
44
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