• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Video sync generator IC

Status
Not open for further replies.

Arhez

New Member
Hello all, I have a board which is a PAL CCIR video sync generator card having SAA1043. The IC is accepting external sync signal from pin 15 ans generating composite pulse on pin 26 and burst output on pin 1. This ic is now obsolete and I am planning to replace this card. While searching for sync generator ICs a mostly find sync separator for example MAX9568. My questions are
1. What is difference between sync generator and separator? can I use MAX9568 circuit in place of SAA1043 circuit. Would that work?
2. Can replace this card with a Microcontroller based sync generator card? is this doable? if yes any article for guidance? because I am really confused what exactly sync generation is?
I am beginner in video no idea, any help would be appreciated, Hope to hear from experts soon thanks in advance.
 
Last edited:

ronsimpson

Well-Known Member
Most Helpful Member
A sync generator and a sycn separator do the opposite jobs.
Here is the MAX9568. It takes video and strips out all the little pieces.
H. sync, V. sync, C. sync, Clamp, odd or even, etc.
1552019631089.png
 

Arhez

New Member
Thanks for the reply yes I agree but it also generates the Composite Syn on pin CSYNCOUT. Actually I have traced the board circuit and i found following implemented on board. It takes external video in and generates composite sync on pin 26
 

Attachments

ronsimpson

Well-Known Member
Most Helpful Member
The SAA1043 takes a clock and generates timings involved in video. Your part is very programmable.
Some sync generators you program how many pixels there is on a horizontal line. How many clocks long the H. Sync is. Then you get to position where the sync is related to video. How long the front porch is, how long the back porch is. Where the color burst is. How many H. lines there is in the picture. Interlaced or non- interlaced. All that timing is done in a sync generator.
 

ronsimpson

Well-Known Member
Most Helpful Member
A sync stripper does not decide what type of video you will make. It only gets the information from another source.
 

Arhez

New Member
Thanks ronsimpson for this point, Could you please suggest me any part or family or vendor where I can search. Because when I google I find sync separators mostly. This IC is very old and I need to replace this circuit.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
A straightforward line & frame sync generator can be built up with simple logic ICs.

If you also need an input to allow it to lock to an existing video signal, such as for overlaying video or captioning on another image, then it it quite a bit more complex.

The SAA1043 has the option for locking to an external signal.


If you don't need that, the simplest option is a ZNA234E - they are still available on ebay, though not cheap.
Those are actually a pattern generator in a chip, but you can ignore the other outputs and just use the sync signals.

Data: https://www.mikrocontroller.net/wikifiles/9/9e/ZNA234E.pdf

Ebay: https://www.ebay.co.uk/itm/2PCS-X-ZNA234E-DIP16/332459471717?hash=item4d6820f365:g:tVYAAOSw~vpaFsWw

Other than that you are looking at built-up circuits or something like a gate array IC programmed to produce the appropriate timing signals.

Or, a PIC or similar MCU, fast enough to produce the timing signals and, with suitable programming, allow locking to external sync if needed.
 

Arhez

New Member
Thank you so much for your reply. I am checking ZNA234E now. Moreover yes I am interested in some permanent solution as well because again seems this IC will become obsolete soon. Please share some article or paper that can lead me to generate equivalent pulses as SAA1043 I want to program something in C using AVR etc.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
All I can say is I'd start with a software phase locked loop, probably based on one of the timers cycling at line scan rate, plus input capture for sync if needed.

Then a divider to take that down to frame rate, with another input capture for frame sync.

I've done other software / hybrid PLL based gear using PICs but not for video; my last major video system design was back in 1985...


If you do not need the external sync input it can just be a crystal oscillator plus a chain of dividers & some appropriate gating to generate the output pulses; it's a lot simpler if it does not need to lock to another signal.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
Presumably, yes.

What type of equipment is it in? Some kind of video processor or video camera?
 

Arhez

New Member
As far as I know its video processor. I have traced the card and attaching complete schematics. Kindly let me know if it makes some sense.
 

Attachments

rjenkinsgb

Well-Known Member
Most Helpful Member
The SA1043 is using a phase locked loop so it can sync to the external input; it would need either a similar scan controller IC for an analog TV, or a system built using a microcontroller and generating the signals with a combination of internal timers and software.

For current, off-the-shelf production parts, you would be looking at something like this, but ignoring most of the video side, just using an input for the external sync and the outputs from the timing processor section:
http://www.ti.com/product/TVP5160
 
Status
Not open for further replies.

EE World Online Articles

Loading
Top