Figure 31: Hdmi Video Fifo - Analog Devices Advantiv ADV7604 Hardware Manual

T M D S +
-
C l o c k
+
T M D S
-
C h a n n e l 0
T M D S
+
-
C h a n n e l 1
T M D S +
-
C h a n n e l 2
DCFIFO_LEVEL[2:0], HDMI Map, Address 0x1C, [2:0]
DCFIFO_LEVEL[2:0] returns the distance between the read and write pointers (a comparison is
performed after dropping the LSB from both pointers).
Function
DCFIFO_LEVEL[2:0]
000
001
010 ~ 011
100
101 ~ 110
111
DCFIFO_LOCKED, HDMI Map, Address 0x1C, [3]
DCFIFO_LOCKED goes high when the FIFO has not needed to resynchronize the write pointer
during one full field/frame. This status bit can be used to estimate when the HDMI system has
achieved lock.
Function
DCFIFO_LOCKED
0
1
Rev. F August 2010
T M D S
P L L
T M D S C h 0
1 0
T M D S
S a m p l in g
T M D S C h 1
a n d
1 0
D a t a
R e c o v e r y
T M D S C h 2
1 0

Figure 31: HDMI Video FIFO

Description
Read pointer and write pointer have collided – FIFO has underflowed
or overflowed
Read pointer is very close to write pointer – FIFO is about to overflow
FIFO has some margin
Maximum distance between read and write pointers – FIFO perfectly
balanced
FIFO has some margin
Write pointer is very close to read pointer – FIFO is about to
underflow
Description
FIFO had to resynchronize between previous two VSyncs
FIFO did not have to resynchronize between previous two VSyncs
117
D i v i d e r
R
1 2
G
1 2
T M D S
B
D e c o d i n g
1 2
H S
V S
D E
ADV7604
D P L L
R
1 2
G
1 2
B
F I F O
1 2
H S
V S
D E