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11-4 SA-1100
Developer’s Manual
Peripheral Control Module
11.3 Interrupts
Each peripheral unit interfaces to the interrupt controller within the system control module. The
interrupt controller contains a 32-bit interrupt pending register, which when read, informs the user
of all the units on the SA-1100 that are currently generating an unmasked interrupt. Once the user
determines which unit is causing the interrupt, the unit’s status registers can be read to determine
the exact cause of the interrupt. This mechanism provides a two-level approach to identify the
source of any interrupt from the hundreds of possible interrupt sources that exist on the SA-1100.
Each of the peripheral units generate either one or two interrupts that correspond to specific
interrupt pending bits within the interrupt controller. Serial ports 1 and 4 each contain two
independent serial engines. Although each peripheral uses only one set of pins for serial
communication, the user may choose to use both serial engines within serial ports 1 and 4 by
assigning one of the two protocols to communicate off-chip by taking control of GPIO pins.
Because the two engines within serial ports 1 and 4 can operate at the same time, these two units
are assigned two separate interrupt request numbers within the interrupt controller’s pending
register. Table 11-3 shows the interrupt level for each of the peripheral control units.
Table 11-3. Peripheral Units’ Interrupt Numbers
Peripheral
Interrupt
Number
LCD controller 12
Serial port 0: USB 13
Serial port 1:
SDLC 14
UART 15
Serial port 2: ICP 16
Serial port 3: UART 17
Serial port 4:
MCP 18
SSP 19