CPM-QE/ RCM
HARMAN BECKER AUTOMOTIVE SYSTEMS GMBH
2018-06-15 12:30:00
CONFIDENTIAL / ALL RIGHTS RESERVED
Regulatory Compliance Management
Manual Hermes
page 9 of 18
3.1.3 Audio
The block diagram below shows the audio path:
The HERMES provides the following audio connections:
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Microphone in (Connection for up to two external microphones (single ended )
-
ECall Speaker output (Connection for an external eCall speaker 10W (differential))
It is possible to configure the microphone inputs as single ended or differential. For converting the
analogue microphone lines and to feed the analogue power-amplifier it is necessary to have an AD-
DA converter. The Hermes uses for this purpose the stereo Audio CODEC from TI
The following requirements have to be fulfilled and adjusted by the CODEC.
Digital Audio Interface:
-
Bit Clock: 2.048MHz
-
Sync: 8kHz
-
Frame: Short frame
-
Data format: 16Bit MSB first
-
Mode: Slave
Line out:
-
Type: differential
-
Output level: 0,707Veff max
Microphone in:
-
Type: single ended
-
Input level: 0,707Veff max.
-
Mic1R: Left channel, max. Gain
-
Mic1L: Right channel, max. Gain
eCall speaker:
-
10W class D power amplifier. The amplifier is only used in case of an eCall.
-
The audio downlink path from the NAD is directly connected to the power amplifier.
All settings have to be done via the I2C control interface. The TLV320AIC3104 supports the I2C
control protocol using 7-bit addressing and is capable of both standard and fast modes.
