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Confidential Draft
3/7/00
CS4281 Programming Manual
228
DS308PRM1
A number of outputs were not included due to
excess control-logic needed. The INTA-C output
pins are not included due to high-impedence
controls. The REQ#, INTA#, and PME# aren’t
included due to being open-drain. The JACX,
JACY, JBCX, and JBCY pins were not included
due to the analog nature of the inputs and the
clamp transistors.
5) Bypass clock multiplier, input 512
×
fs clock
The internal 2
×
clock multiplier will be bypassed.
The clock on the
VOLUP
pin will be used as a
512
×
Fs clock. All other function operate normally.
This is used to synchronously drive the core clock
when running full speed vectors.
6) DLL monitor
Drive the 4x master clock from the clock
multiplier out to the
VOLDN
pin. All other
functions operate normally. This is used to test the
DLL lock range and duty cycle.
7) Scan Test
Enable scan testing. If in Scan Test mode, bringing
JAB1 high sets the Scan Active, and JACX goes
high as an indication that Scan is active. Three
independent scan chains in the CS4281 support
each of the three main internal clocks:
pci_clk
,
clk256
(
abitclk
), and
clk512
. The other joystick
button pins are the scan input signals and the other
joystick coordinate pins are the scan output
signals. The
PCICLK
pin is the scan clock for the
pci_clk
scan chain which contains all the PCI
blocks. The
ABITCLK
pin is the scan clock for the
clk256
scan chain which contains the FM and
Peripheral Interface blocks. The
VOLUP
pin is the
scan clock for the
clk512
scan chain which contains
the SRC and Sound System blocks. While in scan
test mode the DLL is bypassed and external clock
pins are connected to the appropriate internal
clocks as mentioned above. The table below
defines the pin usage for the Scan Test Mode.
23.7
Test Observation Registers
Two of the three Test Observation Registers are
planned: one for observing the Sound Blaster state
machine, and another for observing the AC Link
state machine.
Name
Description
Direction
JACX
Scan Active Indication
OUT
JACY
pci_clk
Scan Data Output
OUT
JBCX
clk256
Scan Data Output
OUT
JBCY
clk512
Scan Data Output
OUT
JAB1
Scan Enable
IN - PU
JAB2
pci_clk
Scan Data Input
IN - PU
JBB1
clk256
Scan Data Input
IN - PU
JBB2
clk512
Scan Data Input
IN - PU
ABITCLK
clk256
External Scan Clock
IN
PCICLK
pci_clk
External Scan Clock
IN
VOLUP
clk512
External Scan Clock
IN
Table 40. Scan Test Mode Pin Usage
D
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