Datasheet 489
LPC Interface Bridge Registers (D31:F0)
13.4.7 OCW1—Operational Control Word 1 (Interrupt Mask)
Register
Offset Address: Master Controller – 021h Attribute:R/W
Slave Controller
– 0A1h Size: 8 bits
Default Value: 00h
13.4.8 OCW2—Operational Control Word 2 Register
Offset Address: Master Controller – 020h Attribute: WO
Slave Controller
– 0A0h Size: 8 bits
Default Value: Bit[4:0]=undefined, Bit[7:5]=001
Following a part reset or ICW initialization, the controller enters the fully nested mode
of operation. Non-specific EOI without rotation is the default. Both rotation mode and
specific EOI mode are disabled following initialization.
Bit Description
7:0
Interrupt Request Mask — R/W. When a 1 is written to any bit in this register, the
corresponding IRQ line is masked. When a 0 is written to any bit in this register, the
corresponding IRQ mask bit is cleared, and interrupt requests will again be accepted by
the controller. Masking IRQ2 on the master controller will also mask the interrupt
requests from the slave controller.
Bit Description
7:5
Rotate and EOI Codes (R, SL, EOI) — WO. These three bits control the Rotate and
End of Interrupt modes and combinations of the two.
000 = Rotate in Auto EOI Mode (Clear)
001 = Non-specific EOI command
010 = No Operation
011 = *Specific EOI Command
100 = Rotate in Auto EOI Mode (Set)
101 = Rotate on Non-Specific EOI Command
110 = *Set Priority Command
111 = *Rotate on Specific EOI Command
*L0 – L2 Are Used
4:3 OCW2 Select — WO. When selecting OCW2, bits 4:3 = 00
2:0
Interrupt Level Select (L2, L1, L0) — WO. L2, L1, and L0 determine the interrupt
level acted upon when the SL bit is active. A simple binary code, outlined below, selects
the channel for the command to act upon. When the SL bit is inactive, these bits do not
have a defined function; programming L2, L1 and L0 to 0 is sufficient in this case.
Code Interrupt Level Code Interrupt Level
000b IRQ0/8 000b IRQ4/12
001b IRQ1/9 001b IRQ5/13
010b IRQ2/10 010b IRQ6/14
011b IRQ3/11 011b IRQ7/15
To Next Page
