ICS2008B

10

ICS2008B Rev D 4/05/05

Timer Control Registers IR3C & IR3D

These two registers control the interrupt timer. It should be

noted that IR3C is a write only register, while IR3D is a read/

write register.

TMRVAL — These ten bits set the divider value for the inter-

rupt timer. The interrupt rate is the input clock rate divided by

the value plus one.

Interrupt Rate = CLOCK /(TMRVAL+1)

CLKSEL — This 2 bit field selects the clock source for the

interrupt timer. The 100 kHz input is actually 100.126 kHz. It

is the crystal frequency divided by 143.

RUN — This bit starts and stops the timer. When set to one,

the timer is running. When set to zero, the timer is stopped.

BLINK — This bit controls the upper dot of the right-most

colon in the burn-in-window. When set to zero, the upper dot

is on. When set to one, it is off. This feature can be used to

indicate odd and even fields in the time code display window.

WINATTR — These two bits control the color of the

characters and the background in the burn-in window. When

the most significant bit of this field is a one, the background is

the incoming video.

WINSIZ — This bit controls the size of the burn-in window.

The difference in size between a large and a normal-sized

window is 32 scan lines high, while a large window is 64 scan

lines high.

HSF (Head Switch Filter) — When set to one, this bit causes

the clamp circuit to ignore head switch transients and

horizontal sync during the last six to seven lines before the

vertical front porch. Otherwise, the clamp circuit responds

always.

LTC Soft Sync IR3F

IR3f is not a register at all. It is simply an address which,

when written and the LTC SYNC select is set for Soft SYNC,

generates LTC SYNC for the LTC transmitter.

Timer Value (w/o)

TMRVAL [7:0]

IR3C

7

6

5

4

3

2

1

0

Timer Control (r/w)

TMRVAL [9:8]

Reserved

CLKSEL

(00-LXCLK, 01-LRCLK)

(10-reserved, 11-100 kHz)

RUN (1-run, 0-stop)

IR3D

7

6

5

4

3

2

1

0

Burn-in Window Attributes

BLINK [1-blink, 0 -stable]

WINATTR

(00 -white on black)

(01-black on white)

(10-white on background)

(11-black on background)

(10-reserved, 11-100 kHz)

WINSIZE

(1-large, 0-normal)

HSF (1-enable, 0-disable)

Reserved

IR3E

LTC Soft SYNC (w/o, no data)

7

6

5

4

3

2

1

0

IR3F

7

6

5

4

3

2

1

0