Integrator's Manual GR47/GR48

5. SYSTEM CONNECTOR INTERFACE

LZT 123 7589 R1A

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.

1RWHV 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.

5.15 Extended I/O capabilities

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.

Using Embedded Applications

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.

1RWH 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.

5.15.1 LED/IO6 Capabilities

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.

Parameter Min. Typ. Max. Units

Input impedance (pull-up) 50 100 120 kΩ