Cinterion
®
Java Terminals Hardware Interface Overview
3.6 GPIO Interface
39
EHSxT_BGS5T_HIO_v03
2016-05-26
Confidential / Released
Page 28 of 50
3.6.2
Digital Audio Interface
Four pins at the Java Terminals‘ GPIO connector can be configured as digital audio interface
(DAI). The DAI can be used to connect audio devices capable of pulse code modulation (PCM).
The PCM functionality allows for the use of an external codec like the W681360.
The DAI interface supports a 256kHz, long frame synchronization master mode with the follow-
ing features:
•
16 Bit linear
•
8kHz sample rate / 125µs frame duration
•
The most significant bit MSB is transferred first
•
Data write at rising edge / data read at falling edge
•
Common frame sync signal for transmit and receive
The following pins at the GPIO connector can be configured as DAI/PCM interface signals:
TXDDAI, RXDDAI, TFSDAI and SCLK (see also
). The configuration is done by
. It is non-volatile and becomes active after a module restart. DAI/
PCM and GPIO functionalities for these lines are mutually exclusive.
describes the
available DAI/PCM lines at the digital audio interface
1
.
shows the PCM timing for the master mode available with Java Terminals.
Figure 8:
Long frame PCM timing, 256kHz
1.
Note:
For the DAI interface to operate, the directions of the Java Terminals‘ GPIO level shifters must
be set according to the defined directions of the DAI signals.
Table 14:
Overview of DAI/PCM signals
Signal name
Input/Output
Description
TXDDAI (GPIO20)
O
PCM data from
Java Terminals
to external codec.
RXDDAI (GPIO21)
I
PCM data from external codec to
Java Terminals
.
TFSDAI (GPIO22)
O
Frame synchronization signal to external codec:
Long frame (8kHz)
SCLK (GPIO23)
O
Bit clock to external codec: 256kHz
SCLK
TXDDAI
RXDDAI
TFSDAI
MSB
MSB
LSB
LSB
14
13
14
13
1
1
12
12
2
2
MSB
MSB
125
µs
