Interrupt Sources - NEC µPD72257 Preliminary User's Manual

Chapter 7

7.5.1 Interrupt sources

VOnMBEINT
VOnVCPINT
VOnNBAINT
Caution
VOnFUFINT
VOnINT
198
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.
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.
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
pulse
• VOnLCDCONTROL.LCDVCOMP[1:0] = 01
porch
• VOnLCDCONTROL.LCDVCOMP[1:0] = 10
video data
• VOnLCDCONTROL.LCDVCOMP[1:0] = 11
porch
You can clear the interrupt by writing VOnLCDICR.VCOMPIC = 1.
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.
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.
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.
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.
Preliminary User's Manual S19203EE1V3UM00
Video Output
: at start of the HSYNC
B
: at start of the back
B
: at start of the active
B
: at start of the front
B