cs5535 National Semiconductor Corporation, cs5535 Datasheet - Page 132

• Manufacturer Part Number: cs5535
• Description: Geode Cs5535 Companion Multi-function South Bridge
• Manufacturer: National Semiconductor Corporation

www.national.com
UART/IR Controller Functional Description
4.11.3.2 Virtual Dongle
The virtual dongle interface is used due to the unavailability
of pins for dongle identification and configuration (see Fig-
ure 4-36).
The virtual dongle interface is a method used to run legacy
software on the UART/IR Controller. The virtual dongle
interface uses dedicated UART/IR MSRs. (See Section
5.12.1 "UART/IR Controller Specific MSRs" on page 363
for complete register and bit formats.) The virtual dongle
imitates the real dongle as far as legacy software is con-
cerned, and there are no plug-and-play requirements for IR
transceivers.
• The software inputs the dongle's ID to the ID[0:3] bits of
• For dongles that use a non-serial transceiver, it identifies
MSR_UART[x]_MOD (UART1 MSR 51400038h and
UART2 MSR 5140003Ch) as the primary ID encoding.
the Consumer IR capabilities. The software should
switch ID1 and ID2 to output mode (so they become
IRSL1 and IRSL2), IRSL1 and IRSL2 will or will not
behave differently (i.e., INV [invert] or NCH [no change])
from the previous step and the software should respond
by driving the appropriate level on ID0 and ID3 in the
MSR_UART[x]_DONG register.
ID1
ID1
ID2
MSR_UART[x]_MOD
ID2
IRRX1
ID0
IR Transceiver
ID0
Figure 4-36. Virtual Dongle Interface
ID3
IRTX
UART/IR Controller
Mux
132
IR Controller
(Continued)
ID0_SEC ID3_SEC
The operational mode of an infrared dongle that uses a
non_serial transceiver is selected by the driving the
IRSL[2:0] signals.
Features
• Uses only three pins to connect to IR transceiver.
• Fully supports legacy software written for real dongle,
• All real dongle modes can be supported by changing the
Limitations
• No Plug-and-Play features available.
• IRSL1 and IRSL2 pins need to be tied in the IR trans-
• MSR contents must be changed when changing the
• If the legacy software supports IR transceiver configura-
with some manual intervention.
MSR.
ceiver for the required mode.
transceiver mode. If BIOS is used to change the MSR
contents, it must be a factory setting.
tion, the contents of IRSL[2:0] are to be read from the
MSR and the required bit tieing needs to be done in the
transceiver board.
ID3
MSR_UART[x]_DONG
IRSL1
IRSL2
ASIC Boundary
IRSL0
IRSL1
and IRSL2
Tie IRSL1
IRSL2
Revision 0.8