Fizzi Lag Tester - Open Sourced

[Fizzi]

Hello potential lag tester! This is an extremely long overdue post but I guess it's better late than never. What feels like an incredibly long time ago, I wrote an article about lag ( http://www.meleeitonme.com/this-tv-lags-a-guide-on-input-and-display-lag/ ). Some time after that I refined my technique to get even more accurate numbers, I did this by designing a board and homebrew app combination that could detect audio/video sync differences between different monitors. I made a demonstration video sometime later ( https://www.youtube.com/watch?v=UTNUIQtreXQ ).

Anyway, at the time of writing I've been working at smashgg for about a year. I have very little free time and quite frankly can spend almost none of it helping people build lag testers, or test lag myself on a variety of set ups. Because of this I wanted to open up everything I did to the public so that hopefully others can replicate it. The ideal scenario for me would be that this stuff takes on a life of it's own and you guys can help each other to refine lag testing techniques.

Anyway, without further ado, here is the github link where I have recently updated the readme and organized the files: https://github.com/JLaferri/LagTestHomebrew/ . Currently the most recent eagle file is missing so I'll try to find that if I can, otherwise everything else should be there. You can still get boards made by clicking the osh park link and download the gerbers from there if you'd like to use a different fab.

 

[BluntMaster]

yay jas! :D

 

[Shank-]

Thanks for doing this for us Fizzi. I have a few suggestions for cost reduction:

1: The board contains quite a bit of empty space. Since circuit board manufacturers charge by the size of the board, moving everything closer together to make it smaller could reduce the cost.

2: The device uses 5v to power it, which it gets by running a 9v battery though a linear regulator. The two could be eliminated altogether by powering it off of one of the wii's USB ports. Just have a mini/micro USB port on the lag tester, so you could use a USB cable to connect it to one of the wii's 2 ports.

3: I believe a simpler, less expensive alternative standalone version could be made to test a screen's latency. It would be able to test a screen's lag without a wii. Using a raspberry pi, we could output the signal though the composite or HDMI line, and have a photo sensor similar to yours. Since the device itself is whats outputting the signal, we wouldn't need audio feedback. This woud be great for users who aren't savvy with a soldering iron. You could also test a bunch of TVs, say at a goodwill, quickly without needing to set up a wii rig on every single one.

 

[Fizzi]

Thanks for doing this for us Fizzi. I have a few suggestions for cost reduction:

1: The board contains quite a bit of empty space. Since circuit board manufacturers charge by the size of the board, moving everything closer together to make it smaller could reduce the cost.

2: The device uses 5v to power it, which it gets by running a 9v battery though a linear regulator. The two could be eliminated altogether by powering it off of one of the wii's USB ports. Just have a mini/micro USB port on the lag tester, so you could use a USB cable to connect it to one of the wii's 2 ports.

3: I believe a simpler, less expensive alternative standalone version could be made to test a screen's latency. It would be able to test a screen's lag without a wii. Using a raspberry pi, we could output the signal though the composite or HDMI line, and have a photo sensor similar to yours. Since the device itself is whats outputting the signal, we wouldn't need audio feedback. This woud be great for users who aren't savvy with a soldering iron. You could also test a bunch of TVs, say at a goodwill, quickly without needing to set up a wii rig on every single one.

1: Yeah, in it's current form factor without a case I figured a bigger board would be easier to hold. Ideally it would be optimized and put in a case of some sort. I just didn't really have the time or desire to get it to that state.

2: Agreed again. I guess I wanted it to be portable and it's kind of nice to limit the amount of wires connected to it. Another solution might be to use a rechargeable lipo battery or something but I think I looked into that and also the microprocessor specs and it was better to use a higher voltage supply. Anyway I'll try to find the most up to date eagle file and people are welcome to make modifications.

3: I've had this same idea - I just didn't have much experience with a raspberry pi and never got around to it. It sounds like a lot of fun for someone to work on. I definitely support anyone that wants to attempt it . If someone did do this it would work more similarly to this device: http://www.leobodnar.com/shop/?main_page=product_info&products_id=212 . As I've stated before though, one of the reasons I wanted to use the Wii was to ensure the video output was identical as when you play. I think the leo bodnar tester outputs in 720p/1080p

 

[Shank-]

I just got the OSH boards in the mail and have started work on soldering parts from the recommended Digikey batch. So far I have soldered about half the SMD resistors/capacitors. The soldering guide seems to be for an old version, 2014 compared to 2015 on the board Im using, but I am assuming the components in the same place are the same.

I have a few questions/notes:
-The batch came with several (30) 100k resistors. What are they used for?
-The diagram has a 5k resistor in the top left, but it was not included in the batch. Should I order one? If so, what package is it?
-The number of 10k resistors in the order is much more than the number actually used.

Side note, these tiny SMD resistors are pretty unpleasant to solder. If i may, Id like to request that version 4 use thru hole resistors instead.

 

[Fizzi]

I just got the OSH boards in the mail and have started work on soldering parts from the recommended Digikey batch. So far I have soldered about half the SMD resistors/capacitors. The soldering guide seems to be for an old version, 2014 compared to 2015 on the board Im using, but I am assuming the components in the same place are the same.

I have a few questions/notes:
-The batch came with several (30) 100k resistors. What are they used for?
-The diagram has a 5k resistor in the top left, but it was not included in the batch. Should I order one? If so, what package is it?
-The number of 10k resistors in the order is much more than the number actually used.

Side note, these tiny SMD resistors are pretty unpleasant to solder. If i may, Id like to request that version 4 use thru hole resistors instead.

Yeah the order was probably not entirely accurate. It's often cheaper to order a bunch of resistors than a small number, that's why some numbers probably don't add up. It's also good to have spares too in case you lose one.

As far as SMD is concerned... you kinda get used to it. SMD resistors do allow you to do some nice things like mess around with changing resistance values when prototyping by stacking them (parallel), or make liked a triangle (series). They're also much smaller. I think the EAGLE files are provided right? You're more than welcome to make a version that has through hole resistors. If you do, feel free to make a pull request on GitHub with the file so others can use it.

 

[DRGN]

I really like the idea of a standalone device. I can understand the thought of using a Wii to ensure a true testing scenario, but either way you would still get objective numbers on the display's response time. And you could always do a direct comparison between the new device and the Wii on a few different monitors, so then you could calibrate it to behave like (i.e. simulate the signal generating time the same as) a Wii. I would guess that that would be a super small variance anyway.

I just got the OSH boards in the mail and have started work on soldering parts from the recommended Digikey batch. So far I have soldered about half the SMD resistors/capacitors. The soldering guide seems to be for an old version, 2014 compared to 2015 on the board Im using, but I am assuming the components in the same place are the same.

I have a few questions/notes:
-The batch came with several (30) 100k resistors. What are they used for?
-The diagram has a 5k resistor in the top left, but it was not included in the batch. Should I order one? If so, what package is it?
-The number of 10k resistors in the order is much more than the number actually used.

Side note, these tiny SMD resistors are pretty unpleasant to solder. If i may, Id like to request that version 4 use thru hole resistors instead.

A few tips for soldering SMD components:

• Use two soldering irons instead of one (one in each hand), so that you can pincer the part and pick-up/solder both sides of it simultaneously (don't need to be expensive at all; last time I needed to do some emergency SMD work, I ran out and got two $5 ones from wal-mart)
• You probably already know that clean solder & iron tips can do wonders, but it's even more important at smaller scales, like SMD work, because of the increase in affect of surface tension, which can actually greatly help in placing the part.
• Use new and thin tips for your irons, clean them often, and don't let them sit hot without solder on them (or else they'll oxidize quickly)
• Might be worth mentioning that a large white mat/paper laid under your work space could be useful for finding a part when you drop one

 

[Fizzi]

Personally for SMD soldering I'll use a reflow technique with tweezers. Add solder to both resistor pads, place resistor over pads with tweezers held in left hand, use right hand with iron to reflow the solder onto the resistor. It's good to then go back and add a little bit more solder (and as such, flux) to both pads again to ensure a good connection.

 

[Shank-]

I personally prefer SMD components. Once you get the hang of it, SMD can be faster and easier than thru hole. I was able to solder them all no problem. Once I order the remaining components I should be ready to go. Im making these mostly to test various screens for portable Wii's, which require more difficult connections than tiny SMD resistors.

However, I feel that the passive components use a smaller package than is necessary. For the experienced, this is a non-issue, but could be too difficult for those less experienced hoping to make one themselves. The board is large and has plenty of empty space, and larger SMD or thru hole components would make assembling these more feasible for the masses. These were originally built for your own personal use, but this is one of many changes that could help allow the average smasher with a soldering iron to build one too.

I was not able to find the eagle file in the GitHub. Once I get the hang of PCB design myself, I may make my own variant designed for ease of assembly for mass adoption.

Again, I can't thank you enough for not only creating this, but providing it and all its documentation publicly for free.

 

[Fizzi]

I personally prefer SMD components. Once you get the hang of it, SMD can be faster and easier than thru hole. I was able to solder them all no problem. Once I order the remaining components I should be ready to go. Im making these mostly to test various screens for portable Wii's, which require more difficult connections than tiny SMD resistors.

However, I feel that the passive components use a smaller package than is necessary. For the experienced, this is a non-issue, but could be too difficult for those less experienced hoping to make one themselves. The board is large and has plenty of empty space, and larger SMD or thru hole components would make assembling these more feasible for the masses. These were originally built for your own personal use, but this is one of many changes that could help allow the average smasher with a soldering iron to build one too.

I was not able to find the eagle file in the GitHub. Once I get the hang of PCB design myself, I may make my own variant designed for ease of assembly for mass adoption.

Again, I can't thank you enough for not only creating this, but providing it and all its documentation publicly for free.

Yeah I do agree that through hole components are more friendly to newer solderers and I'm totally cool with there being a through hole version made. As far as the Eagle file is concerned, you're right – it's not there. I think I may have actually lost the most recent version... I'll try to look for it when I find some time and if I find it I will add it.

 

[Shank-]

Thanks for all your help so far, Fizzi ! Im nearing completion on my 3 boards! I have a few components left that weren't in the initial order, and will be making an order soon. Once I get those and solder them in i can clean off the flux, program 'em, and they should be good to go!

Since the design in the readme is a little different from the PCB, I have a few questions left.

1: Should the photocell or the light sensor go here? It should go on the back, yes? Does polarity matter?
2 and 3: Do I leave these 2 spaces unoccupied?
4: There is an electrolytic capacitor marked on your soldering diagram, but no value given. What value is it?
5: More of a note than a question. There is a 5k resistor marked here, but not included in the BOM.

Once I finish this, test it, and have the files for the circuit board I would love to redesign it to be less expensive and easier to assemble. Looking forward to it!

 

[Fizzi]

Thanks for all your help so far, Fizzi ! Im nearing completion on my 3 boards! I have a few components left that weren't in the initial order, and will be making an order soon. Once I get those and solder them in i can clean off the flux, program 'em, and they should be good to go!

Since the design in the readme is a little different from the PCB, I have a few questions left.

1: Should the photocell or the light sensor go here? It should go on the back, yes? Does polarity matter?
2 and 3: Do I leave these 2 spaces unoccupied?
4: There is an electrolytic capacitor marked on your soldering diagram, but no value given. What value is it?
5: More of a note than a question. There is a 5k resistor marked here, but not included in the BOM.

Once I finish this, test it, and have the files for the circuit board I would love to redesign it to be less expensive and easier to assemble. Looking forward to it!

Hey Shank. Looks like it's coming along pretty well!

1: Should the photocell or the light sensor go here? It should go on the back, yes? Does polarity matter?
When I first designed this board I wasn't sure if I would use a photocell or a light sensor. I ended up opting for a light sensor. The component intended for what you have marked as 1 is the photocell, which I did not end up using. You can leave this spot blank.

2 and 3: Do I leave these 2 spaces unoccupied?
The intended component for these slots is https://www.digikey.com/product-detail/en/molex-llc/0022284360/WM50014-36-ND/313821 . It was to be able to easily switch between testing the photocell and light sensor. You only have to solder it into the light sensor slot. Use the jumper component to complete the connection: https://www.digikey.com/product-detail/en/3m/969102-0000-DA/3M9580-ND/2071621

4: There is an electrolytic capacitor marked on your soldering diagram, but no value given. What value is it?
This is the spot for the light sensor, and to answer your question from question 1, it should be mounted on the back. Polarity does matter. If memory serves, the longer lead of the light sensor goes into the square pad... but I'm not 100% about this.

http://www.digikey.com/short/3nmhrm <- this is another cart that includes the light sensor and the photocell. You don't need to purchase the photocell

This is the light sensor component:
https://www.digikey.com/product-detail/en/panasonic-electronic-components/AMS302/255-2655-ND/2125641

5: More of a note than a question. There is a 5k resistor marked here, but not included in the BOM.
Hmmm... I think I was going to experiment with this value and I might have just intended on putting two 10k resistors in parallel to get a 5k value. To be honest I don't remember exactly which value I settled. I can try to read it off one of the boards I have assembled... if I still have a board assembled somewhere. I'll try to look into that tomorrow if I remember. Maybe message me on twitter or something to remind me lol.

 

[Shank-]

So to make sure I understand properly:
1: ignore and leave unoccupied
2: Short these two thru holes
3: Short these two thru holes
4: Place light sensor on the back here. polarity is important.
5: Stack 2 10k resistors (parallel), buy 5k resistors, or wait for you to give the proper value?

 

[Fizzi]

So to make sure I understand properly:
1: ignore and leave unoccupied
2: Short these two thru holes
3: Short these two thru holes
4: Place light sensor on the back here. polarity is important.
5: Stack 2 10k resistors (parallel), buy 5k resistors, or wait for you to give the proper value?

3: Don't short this, only one of the two (2 or 3) should be shorted at any given time.
5: I would say just go with a 5k value here but I'll also try to double check in the meantime. Even if the value is incorrect I don't think anything will break, think it's just that the light values will saturate the DAC values worst case. Still... maybe just do it for one of your boards .

The rest is accurate.

 

[Fizzi]

Shank-

I found an older version of the eagle file... I also remember some of the problems the first version had.

There were some components that weren't connected and there used to be a mux on the board which I removed. I started making those changes again but it's late so I stopped. I still committed the file if you're interested in looking at it. I'll finish routing it when I have time.

I also remember I added lines to help show where the sensors are on the board between revisions. Not sure what else I did so I'm not 100% sure this board will function the same but it should be close. I wish I could find that stupid file :\

 

[Shank-]

Shank-

I found an older version of the eagle file... I also remember some of the problems the first version had.

There were some components that weren't connected and there used to be a mux on the board which I removed. I started making those changes again but it's late so I stopped. I still committed the file if you're interested in looking at it. I'll finish routing it when I have time.

I also remember I added lines to help show where the sensors are on the board between revisions. Not sure what else I did so I'm not 100% sure this board will function the same but it should be close. I wish I could find that stupid file :\

I don't actually have eagle, so I will have to download and learn it. The circuit is simple enough that I may just be able to remake it in KiCad from scratch. Do you have a schematic file handy I could look at? Edit: Never mind, I was able to access the SCH file.

Also, what was the verdict on the resistor marked as question 5? Did you figure that out?

 

[Fizzi]

I don't actually have eagle, so I will have to download and learn it. The circuit is simple enough that I may just be able to remake it in KiCad from scratch. Do you have a schematic file handy I could look at? Edit: Never mind, I was able to access the SCH file.

Also, what was the verdict on the resistor marked as question 5? Did you figure that out?

Unfortunately I didn't. I don't have a board handy and I also my multimeter is back in Florida. It's probably safe to assume 5K.

Also I realized the connections on the current Eagle file are currently not quite right I think. I'll try to fix it up this weekend but I'm moving so I might not be able to.

 

[Fizzi]

Alright I committed revision 1.1 of the board which is just revision 1 with the issues fixed... or so I think. I also got rid of the jumpers/shunts since I don't think anyone will be interested in experimenting with a photocell.

 

[MadCrashSJ]

Going back to your MioM article followup, I notice you did a test with a component to VGA adapter/converter from Monoprice. Was it a breakout cable you used for that test, or was it a full converter? If the former, then that provides conclusive evidence that the VGA port on those monitors should not be fed YPbPr signals for low latency, but it still potentially leaves open the option of using a good converter. Monoprice is something tested to induce lag, as evidenced in Kadano's thread, so what of the possibility of using a different converter, like an Extron CVC? It's something I know Kadano has recommended in his thread, so long as it can be afforded, but I have yet to see anything in the thread showing test results for a monitor like the BenQ or Asus models you've tested and recommended with your research.