Advanced I/O Controller with Motherboard GLUE Logic
Datasheet
7.25.8 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 LPC47M182 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.
7.25.9 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 LPC47M182 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.
8042 PINS
The 8042 functions P17, P16 and P12 are not supported in LPC47M182.
7.25.10 External Keyboard and Mouse Interface
Industry-standard PC-AT-compatible keyboards employ a two-wire, bidirectional TTL interface for data
transmission. Several sources also supply PS/2 mouse products that employ the same type of interface.
To facilitate system expansion, the LPC47M182 provides four signal pins that may be used to implement
this interface directly for an external keyboard and mouse.
The LPC47M182 has four high-drive, open-drain output, bidirectional port pins that can be used for
external serial interfaces, such as external keyboard and PS/2-type mouse 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. The MDAT pin is
connected to P11.
Note: External pull-ups may be required.
7.25.11 Keyboard Power Management
The keyboard provides support for two power-saving modes: soft powerdown mode and hard powerdown
mode. In soft 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.
Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)
120
SMSC LPC47M182
DATASHEET
SMSC [ SMSC CORPORATION ]
