
Philips
Semiconductors, Inc.
USB-CODEC UDA1325PS
Technical Report
DML98022
2.1.1 No Digital I/O configurations
9
This port configuration can be chosen via the configuration map at start-up of the UDA1325PS. The following
table gives an overview of the different functions assigned to the respective pins for the “No Digital I/O”
communication mode:
Table 2-1
No Digital I/O communication
Pin
GP5 Connect / Disconnect
(2)
GP4 HID input 2
(1) (5)
GP3 HID input 1
(1) (5)
GP I/O
Pin
I/O Expander
(6)
P0
HID input 3
(1) (5)
HID input 4
(1) (5)
HID input 5
(1) (5)
HID input 6
(1) (5)
P1
P2
GP2 Selector output
GP1 Mute or standby output
(3) (4)
P3
P4
Output pin 1
GP0 Interrupt input
P5
Output pin 2
P6
Output pin 3
Mute or standby output
(3) (4)
P7
Notes:
(1) All input pins must be defined at a certain voltage level by means of pull-up resistors or pull-down resistors.
(2) Connect / Disconnect: Holds the USB disconnected as long as the initialization is not finished.
(3) Standby is toggled if the mute is active for 2 minutes programmable time and no ISO data on USB bus.
(4) Mute is toggled if the isochronous (ISO) data flow is interrupted.
(5) For selection of HID application see HID report descriptors in
UniCoDes
.
(6) For the I2C expander, the PCF8574P Remote 8 bit I/O expander for I2C-bus can be used.
2.1.1.1
Functions within the “No Digital I/O configurations” - mode
* Disconnect/Connect (GP5) functionality:
Pin GP5 is used to avoid malfunction during initialization phase. It is
very important
to use this functionality
within your application. While initializing, the Universal Serial Bus remains disconnected and the configuration
selection diodes or the contents of the I2C EEPROM are read in. As soon as the
μ
Controller is ready for regular
operation, the Universal Serial Bus gets connected and the configuration selection diodes are switched off. In the
time-scale we will see the following happening:
3.3V
0 t (ms)
CODEC initialization, USB-bus disconnected.
Figure 2-3
Connect/ Disconnect phase after power-up.
IMPORTANT:
Recently, we have introduced a new Disconnect/Connect circuit to improve the enumeration behavior of the
USB-CODEC’s. Please contact your local FAE or check the USB-AUDIO website to download the report
REP0021.PDF
which explains why and how to implement the newly introduced circuit.