FDC37B78X SMSC Corporation, FDC37B78X Datasheet - Page 131

• Manufacturer Part Number: FDC37B78X
• Description: Enhanced Super I/O Controller with ACPI Support/ Real Time Clock and Consumer IR
• Manufacturer: SMSC Corporation

Host-to-CPU Communication
The host system can send both commands and
data to the Input Data register.
differentiates between commands and data by
reading the value of Bit 3 of the Status register.
When bit 3 is "1", the CPU interprets the register
contents as a command. When bit 3 is "0", the
CPU interprets the register contents as data.
During a host write operation, bit 3 is set to "1" if
SA2 = 1 or reset to "0" if SA2 = 0.
KIRQ
If "EN FLAGS" has been executed and P24 is
set to a one: the OBF flag is gated onto KIRQ.
The KIRQ signal can be connected to system
interrupt to signify that the FDC37B78x CPU has
written to the output data register via "OUT
DBB,A". If P24 is set to a zero, KIRQ is forced
low. On power-up, after a valid RST pulse has
been delivered to the device, KIRQ is reset to 0.
KIRQ will normally reflects the status of writes
"DBB". (KIRQ is normally selected as IRQ1 for
keyboard support.)
If "EN FLAGS” has not been executed: KIRQ
can be controlled by writing to P24. Writing a
zero to P24 forces KIRQ low; a high forces
KIRQ high.
MIRQ
If "EN FLAGS" has been executed and P25 is
set to a one:; IBF is inverted and gated onto
MIRQ. The MIRQ signal can be connected to
system interrupt to signify that the FDC37B78x
CPU has read the DBB register.
If "EN FLAGS” has not been executed, MIRQ is
controlled by P25, Writing a zero to P25 forces
MIRQ low, a high forces MIRQ high. (MIRQ is
normally selected as IRQ12 for mouse support).
Gate A20
A general purpose P21 is used as a software
controlled Gate A20 or user defined output.
The CPU
131
EXTERNAL
INTERFACE
Industry-standard PC-AT-compatible keyboards
employ a two-wire, bidirectional TTL interface
for data transmission.
supply PS/2 mouse products that employ the
same type of interface.
expansion, the FDC37B78x provides four signal
pins that may be used to implement this
interface directly for an external keyboard and
mouse.
The FDC37B78x has four high-drive, open-drain
output, bidirectional port pins that can be used
for external serial interfaces, such as ISA
external
interfaces. They are KCLK, KDAT, MCLK, and
MDAT. P26 is inverted and output as KCLK.
The KCLK pin is connected to TEST0. P27 is
inverted and output as KDAT. The KDAT pin is
connected to P10. P23 is inverted and output as
MCLK. The MCLK pin is connected to TEST1.
P22 is inverted and output as MDAT.
MDAT pin is connected to P11. NOTE: External
pull-ups may be required.
KEYBOARD POWER MANAGEMENT
The keyboard provides support for two power-
saving modes: soft powerdown mode and hard
powerdown mode.
the clock to the ALU is stopped but the
timer/counter and interrupts are still active. In
hard power down mode the clock to the 8042 is
stopped.
Soft Power Down Mode
This mode is entered by executing a HALT
instruction. The execution of program code is
halted until either RESET is driven active or a
data byte is written to the DBBIN register by a
master CPU. If this mode is exited using the
interrupt, and the IBF interrupt is enabled, then
program execution resumes with a CALL to the
interrupt routine, otherwise the next instruction
is executed. If it is exited using RESET then a
keyboard
KEYBOARD
In soft powerdown mode,
and
Several sources also
To facilitate system
PS/2-type
AND
MOUSE
mouse
The