CDB4923 Datasheet, PDF (8/50 Pages) Cirrus Logic – Evaluation Board

CDB4923 CDB49300
PSEL==1 when configuring for I²C mode because
PSEL and SCDIO are multiplexed onto the same
pin.
Two of the DSP jumpers are designed to act as cur-
rent measurement points for the CS492x/CS493xx.
Jumper J59 is the analog current measurement
point, and it must be installed for the PLL to func-
tion. Jumper J60 is the digital current measurement
point, and it must be installed in order to supply
power to the digital logic of the CS492x/CS493xx.
Jumper J1 is the clock selection jumper. When J1 is
in the ’CLKIN’position, the clock present on pin 30
of the DSP (CLKIN) will drive the internal DSP
clocks directly. When J1 is in the ’PLL’ position,
the clock present at pin 30 is used as the reference
clock for the CS492x/CS493xx internal PLL. The
frequency required for the reference clock when
using the internal PLL is application code depen-
dent, so the relevant application code user’s guide
should be consulted to determine which frequency
to provide.
RD WR PSEL
J3
J2
J62
0
1
1
1
0
X
1
1
0
1
1
1
Host Interface Mode
Serial I²C (PSEL==SCDIO)
Serial SPI
8-bit Intel
8-bit Motorola
Table 1. CS492x/CS493xx Host Interface Mode Selection
3.2 External Memory
Some CDB4923/300 boards may be shipped with
an external memory board. There two different ex-
ternal memory boards available:
• CRD4923-MEM - external ROM for CS492x
• CDB49300-MEM - external ROM and RAM
for CS493xx
The CS492x requires an external ROM for auto-
boot, and the CS4926 requires an external ROM
when processing DTS audio streams. The
CRD4923-MEM external memory board is tailored
for the CDB4923. The schematic for CRD4923-
MEM can be found in Figure 20.
The CS493xx family has integrated DTS tables, so
a ROM is required only for autoboot. The
CS493xx also has a static RAM interface. The
CDB49300-MEM external memory board is tai-
lored for the CDB49300. The CDB49300-MEM
schematic can be found in Figure 21.
The CDB4923/300 has been designed to interface
to both the CRD4923-MEM and CDB49300-MEM
daughter boards. The card plugs directly on to J11
oriented such that the CS492x/CS493xx is not cov-
ered, as shown in Figure 1.
Please consult the memory map associated with the
revision of ROM installed in the memory card to
determine which code loads are available. The
memory map can be found in the ‘.fmt’ file found
on the included floppy.
4. CONTROL
Control of the CS492x/CS493xx can be accom-
plished in two ways. The CDB4923/300 is shipped
with a parallel computer cable which can be at-
tached to the parallel port (LPT1, LPT2, or LPT3)
of any computer which has a Windows or DOS
based operating system. The parallel port (J29) in-
terface circuitry is illustrated in Figure 6. The soft-
ware shipped with the CDB4923/300 is based on
command-line programs which must be executed
from a DOS prompt. The CDB4923/300 software
provides the means to reset the CS492x/CS493xx,
write control data to the DSP, read control data
from the DSP, and deliver compressed audio. A de-
tailed description of the software can be found in
Appendix F: Board Control Software.
Alternatively, the board can be put into a mode
which tri-states all connections between the PLD
and the DSP (full external mode), or a mode that
tri-states the control lines (external control mode)
of the CS492x/CS493xx while still driving the data
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