05 January 2022

PROJECT: Half-Life 2 AR2, Update #15 - Barrel Planning

With the AR2 Receiver at 95% completion (just need to fix up loom runways once all electronics are finished) the next step is the AR2 Barrel. So below is me scoping out what's involved:


I am hoping to closely match the barrel & muzzle light colours, though I can already tell this is going to be difficult using a single colour/wavelength LED. So suspect will be using a bunch of RGB LEDs to mix the colours till I have something close

One thing to note about RGB LED colour mixing is that you can approximate a target wavelength BUT you can't match it 100% (think RED, GRN, & BLU peaks combining to give a wide spectrum rather than a sharp peak at target wavelength). This won't be an issue for me as it's not like I am making a medical device that requires a specific wavelength of light 

With that in mind I tried recording the RGB values from the game screenshots and then using this neato tool to get approximate wavelengths. Note how some wavelengths are "impossible" (shown with a ★) due to the RGB value being a mix of all 3 primary colours instead of 2; for example the YLW RGB value is comprised of 254/255/134, so here it's the BLU 134 that is being the "issue" as the resulting light colour is not continuous along the visible spectra

Lastly, the barrel has bugger all space for a large PCB (and by extension a large heatsink), so I might have to add a temperature sensor (like I did with the solenoid inside the AR2 Receiver) to make sure things don't get too toasty


The servo used in the AR2 prototype is the Turnigy TGY-R5180MG and as with most servos this is controlled by varying the pulse width. So the plan is to use an I²C compatible PWM generator like the NXP PCA9685 (suspect I will be using the spare channels to drive the RGB LEDs)

And to top it all off I will also add an end-stop sensor to make sure the servo does not do weird stuff. This will likely be the same IR LED & sensor combo that I used on the AR2 Receiver

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