CS4239 Datasheet, PDF (27/98 Pages) Cirrus Logic – CrystalClear™ Portable ISA Audio System

CS4239
CrystalClear^TM Portable ISA Audio System
face is disabled. The DIN/EEN bit is also the
Data In (DIN) signal to read back data from the
E²PROM. The SDA pin is a bi-directional open-
drain data line supporting DIN and DOUT;
therefore, to read the correct data, the DOUT bit
must be set to a one prior to performing a read
of the register. Otherwise, the data read back
from DIN/EEN will be all zeros. The E²PROM
data can then be read from the DIN/EEN bit.
The CLK bit timing is controlled by the host
software. This is the serial clock for the
E²PROM output on the SCL pin. The DOUT bit
is used to write/program the data out to the
E²PROM. An external pull-up resistor is re-
quired on SDA because it is an open-drain
output. Use the guidelines in the specific
E²PROM data sheet to select the value of the
pull-up resistor (a typical value would be
3.3 kΩ).
Programming the E²PROM:
1. Configure Control I/O base address by one
of two methods: regular PnP cycle or Crystal
Key method.
a. The host can use the regular PnP cycle to
program the logical device 2 I/O base ad-
dress, and then place the chip in the
wait_for_key_state
b. If the Crystal Key method is used:
First, write to the AP, send the 32-byte
Crystal key.
Second, configure the Control I/O base
address by writing 15h, 02h, 47h, 01h,
20h, 33h, 01h, 79h to the AP.
2. Refer to the specific data sheet for the
E²PROM you are using for timing require-
ments and data format. Also, refer to the
Loading Resource Data section of this data
sheet for the E²PROM resource data format.
3. Send the E²PROM data in successive bits to
CTRLbase+1 (Hardware Control Register)
while following the E²PROM data sheet for-
mat.
The E²PROM now contains the PnP resource
data. For this new data to take effect, the part
must be reset, causing the part to read the
E²PROM during initialization. Cirrus can pro-
vide a utility, RESOURCE.EXE, to program
E²PROMs through the Control logical device in-
terface.
WINDOWS SOUND SYSTEM CODEC
The WSS Codec software interface consists of
4 I/O locations starting at the Plug and Play ad-
dress ’WSSbase’, and supports 12-bit address
decoding. If the upper address bits, SA12-SA15
are used, they must be 0 to decode a valid ad-
dress. The WSS Codec also requires one
interrupt and one or preferably two DMA chan-
nels, one for playback and one for capture. Since
the WSS Codec and Sound Blaster device are
mutually exclusive, the two devices share the
same interrupt and DMA playback channel.
Part
Bank
Crystal IC Start _Address ^Write _Address
Start
Part
Address
Read
S1 0 1 0 0 0 0 0A0 0 0 0 0 0 0 0 AS1 0 1 0 0 0 0 1A
No
Acknowledge Acknowledge
Stop
Data A
Data 1 P
EEPROM
Acknowledge
Data
Figure 3. EEPROM Format
DS253PP2
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