Integrator's Manual GR47/GR48

5. SYSTEM CONNECTOR INTERFACE

LZT 123 7589 R1A

5.15.2 I#/O#

If pins labelled I# and O# are not being used for an alternative function

they may be used for general purpose inputs or outputs respectively. The

inputs have an on-board 100k pull-up resistor and the outputs are driven

rail-to-rail at 2.75V levels.

5.15.3 UART3/IO#

The UART3 pins have been given alternative functions as general purpose

I/O, both pins may be used for either input or output. However, the TX

pin has a 100kΩ pull-down resistor to ground and the RX pin has a 100kΩ

pull-up resistor to 2.75V. This must be taken into consideration when

designing the host circuit.

5.15.4 IO#/ADC#

To increase analog input capabilities, the radio device optimises the I/O by

multiplexing or sharing different features on single pins. There are two

digital I/O pins which now have an additional ADC input. When

configured as digital I/O, the software will not read the voltages at the two

new ADC inputs. When configured as ADC inputs the software will

configure the digital I/O pins as input or high impedance tri-state. In this

state any applied voltage between 0V and 2.75V can be read as an 8 bit

value.

Because the additional ADC inputs (ADC4 and ADC5) are common with

digital I/O, the input circuit of the ADC is not the same as for the original

circuits ADC1-3. It is important to understand the input structure of the

pin so that the correct analog voltage is read by the application.

5.16 General Purpose Analogue I/O Ports

The radio device is able to convert digital to analogue signals and vice

versa.

Pin Signal Dir Description

20 DAC O Digital to analogue conversion output

26 ADC1 I Analogue to digital conversion input 1

27 ADC2 I Analogue to digital conversion input 2

28 ADC3 I Analogue to digital conversion input 3

13 ADC4 (I/O5) I (I/O) Analogue to digital conversion input 4

22 ADC5 (I/O2) I (I/O) Analogue to digital conversion input 5