CS4235 Datasheet, PDF (19/94 Pages) Cirrus Logic – CrystalClear Low Cost ISA Audio System

CS4235
CrystalClear ^TM Low Cost ISA Audio System
Bypassing Plug and Play
The SLAM method allows the user to bypass the
Plug and Play features and, as an option, allows
the part to act like a non-Plug and Play or legacy
device; however, the SLAM method only sup-
ports one Cirrus Audio IC per system. The user
directly programs the resources into the part, and
then optionally disables the PnP and/or the Crys-
tal Key, which forces the part to disregard any
future PnP or Crystal initiation key sequences
(All activated logical devices appear as legacy
devices to PnP). The Crystal and PnP keys can
also be disabled through the E²PROM. The
SLAM method uses the Address Port (AP) simi-
larly to Plug-and-Play. Although the standard AP
is 279h, two other selections are available for
non-standard implementations. See the Address
Port Configuration section for more details.
To use the SLAM method, the following se-
quence must be followed:
1. Host sends 32-byte Crystal key to the AP,
chip enters configuration mode.
2. Host programs CSN (Card Select Number)
by writing a 06h and 00h to the AP.
3. Host programs the configuration registers of
each logical device by writing to the AP. The
following data is the maximum amount of in-
formation per device. All current devices only
need a subset of this data:
Logical Device ID (15h, xxh)
xxh is logical device number: 0-5
I/O Port Base Address 0 (47h, xxh, xxh)
high byte , low byte
I/O Port Base Address 1 (48h, xxh, xxh)
high byte , low byte
I/O Port Base Address 2 (42h, xxh, xxh)
high byte , low byte
Interrupt Select 0 (22h, xxh)
Interrupt Select 1 (27h, xxh)
DMA Select 0 (2Ah, xxh)
DMA Select 1 (25h, xxh)
Activate Device (33h, 01h)
(33h, 00h deactivates a device)
4. Repeat #3 for each logical device to be en-
abled. (Not all devices need be enabled.)
5. Host activates chip by writing a 79h to AP.
6. (Optional) Host disables PnP Key by writing
a 55h to CTRLbase+5. The part will not par-
ticipate in any future PnP cycles. The Crystal
Key can also be disabled by writing a 56h to
CTRLbase+5.
NOTE: To enable the PnP/Crystal Keys after
they have been disabled by the SLAM
method, bring the RESDRV pin to a logic
high or remove power from the device.
The following illustrates typical data sent using
the SLAM method.
006h, 001h
; CSN=1
015h, 000h
; LOGICAL DEVICE 0
047h, 005h, 034h ; WSSbase = 0x534
048h, 003h, 088h ; SYNbase = 0x388
042h, 002h, 020h ; SBbase = 0x220
022h, 005h
; WSS & SB IRQ = 5
02Ah, 001h
; WSS & SB DMA0 = 1
025h, 003h
; WSS capture DMA1 = 3
033h, 001h
; activate logical device 0
015h, 001h
; LOGICAL DEVICE 1
047h, 002h, 000h ; GAMEbase = 0x200
033h, 001h
; activate logical device 1
DS252PP2
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