SAA7108AE Datasheet, PDF (66/208 Pages) NXP Semiconductors – HD-CODEC

NXP Semiconductors
SAA7108AE; SAA7109AE
HD-CODEC
Table 22. Processing trigger and start
XDV1 XDV0 XDH Description
92h[5] 92h[4] 92h[2]
Internal decoder: The processing triggers at the falling edge of the
V123 pulse [see Figure 33 (50 Hz) and Figure 34 (60 Hz)], and starts
earliest with the rising edge of the decoder HREF at line number:
0
1
0
4/7 (50/60 Hz, 1st field), respectively 3/6 (50/60 Hz, 2nd field)
(decoder count)
0
0
0
2/5 (50/60 Hz, 1st field), respectively 2/5 (50/60 Hz, 2nd field)
(decoder count)
0
0
0
External ITU 656 stream: The processing starts earliest with SAV at
line number 23 (50 Hz system), respectively line 20 (60 Hz system)
(according to ITU 656 count)
9.3.1.2 Task handling
The task handler controls the switching between the two programming register sets. It is
controlled by subaddresses 90h and C0h. A task is enabled via the global control bits
TEA[80h[4]] and TEB[80h[5]].
The handler is then triggered by events which can be defined for each register set.
In the event of a programming error the task handling and the complete scaler can be
reset to the initial states by setting the software reset bit SWRST[88h[5]] to logic 0.
Especially if the programming registers, related acquisition window and scaler are
reprogrammed while a task is active, a software reset must be performed after
programming.
Contrary to the disabling/enabling of a task, which is evaluated at the end of a running
task, when SWRST is at logic 0 it sets the internal state machines directly to their idle
states.
The start condition for the handler is defined by bits STRC[1:0] 90h[1:0] and means: start
immediately, wait for next V-sync, next FID at logic 0 or next FID at logic 1. The FID is
evaluated, if the vertical and horizontal offsets are reached.
When RPTSK[90h[2]] is at logic 1 the actual running task is repeated (under the defined
trigger conditions), before handing control over to the alternate task.
To support field rate reduction, the handler is also enabled to skip fields (bits FSKP[2:0]
90h[5:3]) before executing the task. A TOGGLE flag is generated (used for the correct
output field processing), which changes state at the beginning of a task, every time a task
is activated; examples are given in Section 9.3.1.3.
Remarks:
• To activate a task the start condition must be fulfilled and the acquisition
window offsets must be reached. For example, in case of ‘start immediately’, and
two regions are defined for one field, the offset of the lower region must be greater
than (offset + length) of the upper region, if not, the actual counted H and V position at
the end of the upper task is beyond the programmed offsets and the processing will
‘wait for next V’.
SAA7108AE_SAA7109AE_3
Product data sheet
Rev. 03 — 6 February 2007
© NXP B.V. 2007. All rights reserved.
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