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VSYNC detection

GreenPAK and GreenFET

4 months ago

Posted by Ales Stojan 85 points 6 replies
0 upvotes

We need to detect VSYNC pulse. This is the LATCH pulse, that has exactly two rising edges of CLK when high. It can be up to 31 CLK pulses, but we need to detect just LATCH+2CLK combination. I did not manage to find simple solution. Have you already done something like that, so that I do not discover hot water...?

Attachment Size
Capture.PNG 66.89 KB

4 months ago

olehs

Hi Ales Stojan, 

Thank you for your interest in our product. I looked through your description and come up with a small design. Please see the attached file. Hope I can help you to start or modify the existing design according to your needs. You can also refer to the Cookbook (https://www.dialog-semiconductor.com/greenpak-cookbook), where you can find some basic applications and techniques you can use in your project. 

Best regards, 

Oleh Sapiha

Attachment Size
2clk detector.zip 4.81 KB

4 months ago

Ales Stojan 85 points

First of all, thank you for really fast answer, you gave me idea for different approach to the problem! I was studying your manual, but did not find exactly such case as mine. Where is the problem? I need to get pulse only when there are exactly two CLK pulses within LATCH. And it has to be triggered when LATCH goes down. So if thereis only one or 3,4,...CLK pulses signal should not be generated. For example, if I increase V2 pulse from 400 us to 900 us, I get even two pulses. 

Any additional idea is very welcome. I will also look in a way that you proposed.

Thank you

4 months ago

olehs

Ales Stojan,

Thank you for the detailed explanation. I modified the design a bit, please take a look, maybe this time it works as expected. 

Regarding the Cookbook, of course, it doesn't have exactly the same application, but it has a lot of other different applications, which can help you understand deeply how to work and think in terms of GreenPAK. 

Best regards, 

Oleh Sapiha

Attachment Size
2clk detector_mod.zip 4.96 KB

4 months ago

Ales Stojan 85 points

Now it works fine, except in case there is only one CLK pulse. If you have time can you check this as well. Thank you.

accepted answer!

4 months ago

olehs

Ales Stojan,

Yes, you are right, I should have checked this condition as well:) Now it works, find the modified design in the attachment. 

Best regards, 

Oleh Sapiha

Attachment Size
2clk detector_mod2.zip 4.95 KB
accepted answer!

4 months ago

Ales Stojan 85 points

Thank you for nice solution! Now I even have space to add one other functionality in...