7.5.1 Interrupt sources
The Video Output module generates five interrupts.
In the following all interrupts are described. It is assumed that the interrupts are
unmasked, hence the raw interrupt generates its corresponding system interrupt.
VOnMBEINT
Bus error interrupt
If the Video Output module attempts to access an undefined address range via
the framebuffer base address register VOnLCDUPBASE, the bus error interrupt
VOnMBEINT is generated.
The bus error interrupt serves only for debug purpose.
VOnVCPINT
Vertical compare interrupt
VOnVCPINT is generated when a new output frame starts. The exact point in time
to generate VOnVCPINT can be configured by setting the
VOnLCDCONTROL.LCDVCOMP[1:0] bits:
•
VOnLCDCONTROL.LCDVCOMP[1:0] = 00
B
: at start of the HSYNC
pulse
•
VOnLCDCONTROL.LCDVCOMP[1:0] = 01
B
: at start of the back
porch
•
VOnLCDCONTROL.LCDVCOMP[1:0] = 10
B
: at start of the active
video data
•
VOnLCDCONTROL.LCDVCOMP[1:0] = 11
B
: at start of the front
porch
You can clear the interrupt by writing VOnLCDICR.VCOMPIC = 1.
VOnNBAINT
Next address base update interrupt
The LCD next base address update interrupt VOnNBAINT is generated when the
framebuffer base address VOnLCDUPBASE.LCDUPBASE[31:0] value has been
made effective. This signals to the system that it is safe to update the
VOnLCDUPBASE register with new frame base addresses if required.
You can clear the interrupt by writing VOnLCDICR.LNBUIC = 1.
Caution
The LCD next base address update interrupt VOnNBAINT is generated with each
vertical synchroniozation signal, independent of whether a new address was
written to VOnLCDUPBASE.
VOnFUFINT
FIFO underflow interrupt
The FIFO underflow interrupt VOnFUFINT is generated when internal data is
requested from an empty DMA FIFO.
You can clear the interrupt by writing VOnLCDICR.FUFIC = 1.
VOnINT
Common interrupt
The above interrupts are combined to the single common interrupt VOnINT. Thus
VOnINT is generated whenever any of the other interrupts is active.
Chapter 7
Video Output
198
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