Sony Ericsson GR47/GR48 - Manual (Page 45)

5. SYSTEM CONNECTOR INTERFACE
45
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 100k
Ω pull-down resistor to ground and the RX pin has a 100k Ω
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