Table of Contents
Advertisement
5.15.2 I#/O#
5.15.3 UART3/IO#
5.15.4 IO#/ADC#
5.16 General Purpose Analogue I/O Ports
LZT 123 7589 R1A
5. SYSTEM CONNECTOR INTERFACE
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.
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 pull-down resistor to ground and the RX pin has a 100k
pull-up resistor to 2.75V. This must be taken into consideration when
designing the host circuit.
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.
Pin
Signal
20
DAC
26
ADC1
27
ADC2
28
ADC3
13
ADC4 (I/O5)
22
ADC5 (I/O2)
The radio device is able to convert digital to analogue signals and vice
versa.
Dir
Description
O
Digital to analogue conversion output
I
Analogue to digital conversion input 1
I
Analogue to digital conversion input 2
I
Analogue to digital conversion input 3
I (I/O)
Analogue to digital conversion input 4
I (I/O)
Analogue to digital conversion input 5
45
Advertisement
Table of Contents
