TW2866C datasheet(48/143 Pages) RENESAS

48 / 143 page

TW2866C

FN8253 Rev. 0.00

Page 48 of 143

February 3, 2012

Interrupt Interface

The TW2866 provides the interrupt request function using an IRQ pin so that the host does not need to

waste much resource to detect video or audio signal from TW2866. To use interrupt request function, the

interrupt request should be enabled by the IRQENA and polarity of the IRQ pin should be selected by the

IRQPOL. Also, each channel of video and audio detection should be enabled by the AVDET_ENA. Then, the

interrupt mode should be defined by the VDET_MODE and ADET_MODE that control the time to request

interrupt and set the status register AVDET_STATE. The Figure 40 shows operation of interrupt when the

VDET_MODE and/or ADET_MODE are 2 and 3. The IRQ pin is cleared automatically by reading the

AVDET_STATE. When the VDET_MODE and/or ADET_MODE is 1 or 2, the status register AVDET_STATE will

also be cleared automatically by reading AVDET_STATE. However, when the VDET_MODE and/or

ADET_MODE are 3, the status register AVDET_STATE will not be cleared automatically, but has the same

value as actual status of video and audio detection flag.

0x08

0x00

Read Status Register

Video Detection

on Channel 4

IRQ Pin Output

Status Register

Host Interface

VDET_MODE = 2

(a) Status Register of Automatic Cleared Mode

0x08

0x00

Read Status Register

Video Detection

on Channel 4

IRQ Pin Output

Status Register

Host Interface

VDET_MODE= 3

(b) Status Register same as Video and Audio Detection Flag Mode

FIGURE 40. TIMING DIAGRAM OF INTERRUPT INTERFACE

Squared Pixel Mode Operation

If FC27 register bit is set to 0,TW2866 works under Squared Pixel mode operation.XTI pin input on PAL-SQ

mode should have either 59MHz(=29.5MHzx2) or 29.5MHz.Also,XTI pin input on NTSC-SQ mode should

have either 49.086MHz(=24.543MHzx2) or 24.543MHz. HACTIVE register value should be 0x300(768dec)

for PAL-SQ and 0x280(640dec) for NTSC-SQ.If Audio function is used with this Squared Pixel mode,ACKI

ACKI = round ( F AMCLK / 29.5MHz * 2^23 )………………for PAL-SQ

ACKI = round ( F AMCLK / 24.543MHz * 2^23 )……………for NTSC-SQ

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