Cirrus Logic CRD42L52 - Manual (Page 4)

4 DS680RD1
CRD42L52
1. SYSTEM OVERVIEW
The CRD42L52 provides a quick and general overview of the features in the CS42L52 CODEC in addition to pro-
viding a reference for an ultra-small layout design.
Line, headphone and PWM terminals are accommodated on the board for part evaluation and measurement pur-
poses. The control port and serial audio interfaces are accessible via the I/O stake header used to attach the
CRD42L52 to the CDB42LDB1. The driver board consists of a S/PDIF receiver, a S/PDIF transmitter and a USB
microcontroller and is used to provide data to the CRD42L52. Therefore, in order to operate the CRD42L52 and use
the Cirrus FlexGUI software to configure it, it must be connected to the CDB42LDB1 reference design board. This
section serves to give a general overview of the hardware components used on the CRD42L52 reference design
board and the CDB42LDB1 peripheral driver board.
1.1 Power (U2)
Power can be supplied to the boards by using one of the two power supply options on the CDB42LDB1 driv-
er board. Power is supplied to the driver board either from 3 AAA +1.5 V batteries (placed on the battery
clips behind the driver board) or from an external power supply (J1). The desired power supply must be se-
lected using the appropriate setting on switch S1. The power supply on the driver board is regulated down
to 3.3 V and 1.8 V as shown in the schematic (
Figure 23 on page 22 ) to provide power to the various com-
ponents on the driver board. The I/O header (J3) also contains power supply lines to route a 1.8 V supply
line to power the analog and digital cores of the CS42L52 on the CRD42L52 board.
1.2 Microcontroller (U3)
The USB microcontroller on the CDB42LDB1 driver board drives the I²C
®
control port interface lines to the
CRD42L52 via an I/O stake header and is used to configure the CS42L52. The microcontroller is also used
to enable the CDB42LDB1 to drive the digital audio data and clock lines.
On-board functionality can be controlled by selecting appropriate configuration settings in the provided Win-
dows-compatible FlexGUI software. For a detailed description of the Cirrus FlexGUI software, refer to
Sec-
tion 4. "Software Mode Control" .
1.3 CS8416 Digital Audio Receiver (U7)
The CS8416 is a S/PDIF receiver that converts the S/PDIF data stream received by the board via either the
optical or RCA phono connector into PCM data. This PCM data is routed to the I/O stake header which
routes it to the CS42L52 on the CRD42L52 board.
The CS8416 is configured to operate in hardware master mode and provides the system master clock when
a S/PDIF input source is connected to the board. Should the S/PDIF source become unavailable, causing
a Receiver Error, the system clock is automatically switched to the one provided by the on-board oscillator
for uninterrupted operation of other on-board components receiving the master clock.
A complete description of the CS8416 receiver and a discussion on the digital audio interface are included
in the CS8416 data sheet.
1.4 CS8406 Digital Audio Transmitter (U8)
The CS8406 is a S/PDIF transmitter that converts the PCM data it receives from the I/O stake header into
a S/PDIF data stream. The S/PDIF data can be monitored either via the optical (J7) or RCA phono connector
(J9) on the CDB42LDB1 driver board. The CS8406 is configured to operate in hardware slave mode. It re-
ceives its clocks from the CS8416. In the case of a receiver error, the clock source for the CS8406 is auto-
matically switched to the on-board oscillator for uninterrupted operation of the CS8406.
A complete description of the CS8406 transmitter and a discussion on the digital audio interface are includ-
ed in the CS8406 data sheet.