8.7 Interrupts
The Drawing Engine generates three interrupts.
8.7.1 Interrupt sources
DRWBUSIRQ
Drawing Engine bus error interrupt
If the Drawing Engine attempts to access an undefined address range via the
•
framebuffer base address register DRWORIGIN,
•
texture base address register DRWTEXORIGIN,
•
display list start address register DRWDLISTSTART,
the bus error interrupt DRWBUSIRQ is generated.
The bus error interrupt serves only for debug purpose.
DRWENUMIRQ
Enumeration interrupt
DRWDLISTIRQ
Display list interrupt
The display list interrupt DRWDLISTIRQ is asserted upon completion of a display
list process.
DRWDLISTIRQ is activated if
•
the entire display list has been completed
•
the display list processing has been stopped, because a new display
list start has been triggered by writing to the display list start address
register DRWDLISTSTART
8.7.2 Interrupt control
The three Drawing Engine interrupts are combined to the single common interrupt
DRWINT towards the external Host CPU.
Each interrupt can be masked (disabled), respectively unmasked (enabled), by
setting its enable bit in the interrupt control register DRWIRQCTL.
The occurence of a certain enabled interrupt - its mask bit in DRWIRQCTL is "1"
- is monitored in the status control register DRWSTATUS: its corresponding
interrupt status bit is set to "1" and the common Drawing Engine interrupt DRWINT
is generated.
In order to clear the interrupt the Host CPU has to write a "1" to the interrupt clear
bit in DRWIRQCTL. The interrupt clear bit returns to "0" automatically.
Chapter 8
Drawing Engine
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