cs4239 Cirrus Logic, Inc., cs4239 Datasheet - Page 21

• Manufacturer Part Number: cs4239
• Description: Crystalclear? Ortable Isa Audio System Logic
• Manufacturer: Cirrus Logic, Inc.

If all the above data is sent, after the Crystal key,
all devices except the CDROM will respond to
the appropriate resources given.
Crystal Key 2
A new feature of this part is the addition of an-
other way to bypass the PnP interface using a
new key, designated Crystal Key 2 (CK2). This
new key is designed for Codecs on the mother-
board that are hidden from normal PnP. The
following 32 bytes, in hex, are Crystal Key 2
followed by the upper 8 bits of the Read Data
port (RDP):
This key differs greatly from the original Crystal
Key in that the 33rd byte defines the upper 8 bits
of the 10-bit Read Data port address, with the
lower 2 bits equal to 11. As an example, if the
RDP byte is 0x82, then the actual Read Data
port is 0x20B. Another difference is that the
original Crystal Key uses custom commands and
is write-only; whereas, CK2 places the part in a
PnP Configuration state and uses standard PnP
commands to access PnP configuration registers.
Since CK2 is unique to the CS4239, the PnP iso-
lation sequence is bypassed.
DS253PP2
015h, 002h
047h, 001h, 020h ; CTRLbase = 0x120
033h, 001h
015h, 003h
047h, 003h, 030h ; MPUbase=0x330
022h, 009h
033h, 001h
079h
95, B1, D8, 6C, 36, 9B, 4D, A6,
D3, 69, B4, 5A, AD, D6, EB, 75,
BA, DD, EE, F7, 7B, 3D, 9E, CF,
67, 33, 19, 8C, 46, A3, 51, A8, <RDP>
; activate logical device 2
; MPU IRQ = 9
; activate logical device 3
; activate CS4239 device
; LOGICAL DEVICE 2
; LOGICAL DEVICE 3
CK2 differs from normal PnP in that the RDP is
read/write instead of read-only. In PnP the RDP
is read-only and a second address, designated the
Write Data Port (0xA79), is used to write data
into PnP registers. Using CK2, all configuration
is done through the RDP, there is no Write Data
Port. When finished, a Wait-for-Key command
should be issued to the Address Port which
places the part back in the normal mode of op-
eration. Note that the Address Port (AP) can also
be moved away from the normal PnP location of
0x279. See the Address Port Configuration sec-
tion for more information.
The CK2 configuration sequence is as follows:
1. CK2 32 bytes are sent to the Address Port fol-
2. The AP and RDP are used to read/write con-
6. A Wait-for-Key command is sent removing
The particluar PnP register is set using the Ad-
dress Port and the data for that register is
read/written to/from the RDP. As an example,
when finished configuring the part, to send the
Wait-for-Key command, a 0x02 is sent to the AP
(selecting the Config. Control register) and a
0x02 is sent to the RDP. This causes the part to
exit the configuration state and enter normal op-
eration (Wait-for-Key).
Hardware Configuration Data
The Hardware Configuration data contains map-
ping information that links interrupt and DMA
pins with actual interrupt numbers used by PnP
and SLAM procedures. The Hardware Configu-
ration data precedes the PnP Resource data.
The Hardware Configuration data is either 19 or
23 bytes long and contains the data necessary to
configure the part. If an E
lowed by the upper 8 bits of the RDP.
figuration information in normal PnP fashion.
the part from the configuration state.
CrystalClear Portable ISA Audio System
TM
2
PROM is not used
CS4239
21