BRAND NEW LATENCY TESTER – OSLTT CS is here! (Open Source Latency Testing Tool)
This little guy is the open source latency testing tool CS – that’s chip shortage for short if you were interested – and it’s the latest and greatest version of my open source latency testing tool. This is kind of the V2 of OSLTT, although to assure existing OSLTT owners, they are still very comparable so don’t worry much about having an ‘outdated’ tool, as I’ve proved with the original response time tool, you’ll still get support, firmware updates and software updates going forward. With that said, there are a few key improvements in this thing I’m really excited to share, so let’s dive in!
Much of the board is pretty similar to the original design – including the same microcontroller, the SAMD21G18A, although I’ve moved from using Seeeduino XIAO boards to putting the microcontroller and USB C port on the board myself. The one thing that’s changed here is which board I’ve modelled it after – instead of the Seeed board I’m using the Adafruit Feather M0 bootloader, which should be more reliable than the Seeed option. That does mean that the firmware needs to be complied for both the XIAO board and Feather M0, but luckily I’ve already got support for that in the desktop app so you won’t have any issues with updates, and the good news for me is that it’s the same firmware file between them, so any updates I do for the CS, the original will get too!
The other major improvement to the existing hardware is the audio amplifier for the microphone. The last setup was on the noisy side, compared to the new board it’s night and day better. It’s an order of magnitude less noise, which is what makes the new feature possible – that being automatic gain control. For peripheral testing, like listing for mouse clicks for example, you don’t want it to be too sensitive or you’ll end up with false positive triggers, but for audio testing, like speakers and headphones, you want it to be more sensitive to pick up the sound without it blowing your ears out, so now you get the best of both worlds. The board knows if you are doing an audio test, and if so it switches to the high gain resistor, otherwise it’s the same gain as the original board. This is great, and gives me an incentive to work out how to do low latency audio to get more useful test results! Oh and one more thing on the audio front – there is now a jumper built in to let you switch between three and four pole microphones, should you want to not use the included microphone. By default it’ll be set to 3 pole as that’s what I include in the box, but the option is now there if you want it!
The other big new feature is this, the flyleads. With, let’s just call it V1 for ease here, with V1 it was a 2 pin flylead – ground and signal in. This works great if you want to test peripherals and are willing to solder to the key switch or button, but it isn’t exactly ideal to have to take apart the product, solder to it, then test – and while the audio trigger is an option, if you want the utmost in accuracy, you want to use the flyleads. So, I added another pin. These are now three pin flyleads, with the outermost one being ground, and now the middle being signal in, but the new one is the most inboard. That is a protected signal out pin, which when combined with what I’m calling the peripheral test pack – that being these three pin flyleads which come with a crocodile clip for ground and a banana plug for pressing the button, and a set of aluminium foil tape strips – lets you have your cake and eat it too. Basically, instead of needing to solder to the button, you stick the foil tape to the mouse button, attach the ground clamp to the tape, then start the mouse test mode, and use the banana plug to click your mouse button. This triggers the tool to start the timer between the click and receiving the mouse down event, the same way it ‘hearing’ the click or if you’d soldered to the button instead – but this way you get essentially the most real world way to test devices. The second you start actually pushing on the button or the switch, the tool starts counting. Now the tool is still likely limited on resolution for higher than 1000 hertz peripherals, but this should still be more accurate either way.
Also, if you were wondering how I get the cases made, that’s JLC too. Their 3D printing service is frankly phenomenal – the quality of these resin prints is amazing, I mean just look at the finish on them – and they are exceptionally good value too. They only take a couple of days to print even fairly large orders, and ship quickly too. To be transparent, JLC gave me a discount on these parts, but I’m genuinely happy to recommend them and I’ve been using them ever since I launched OSRTT Pro and I’ve been a legit happy customer ever since. I’ll leave a link to their 3D printing service in the description too.
So yeah, that’s OSLTT CS. A much improved audio amplifier, automatic gain control, and a new, more accurate, and easy way to test peripherals. I’m really proud of this one, and I’m incredibly excited to see these get some use in the hands of some very talented and knowledgeable reviewers – and me of course. If you want one, they are live now as OSRTT.com/osltt-cs, so grab one while I’ve got stock left!
