I designed this so wiring would be dead simple, mostly so my enclosure could be small, but also so debugging would be straight-foward. Note the cramped conditions in my little box. :)

The idler, which fits over a 608ZZ bearing (remove the sheilds and degrease with WD40 so it spins freely). The first requirement was the 5V supply voltage of my rotary encoder. Of the various ESP32 dev boards I had in my stash, only a few supplied true 5V at the Vcc pin when powered by USB. (The others measured 4.5-4.8V, which, in case your math is bad, is lower than 5V.) The board I used was a Wemos Lolin32. Successful prints require a properly-calibrated extruder: when the gcode tells the extruder to move the filament 2mm, it needs to move exactly 2mm. Bad things happen if it over-extrudes or under-extrudes. A well-calibrated counter can keep an extruder honest. The 2401 unit is slung from a stay rod. A hinge arrangement on the stay rod allows the unit to be positioned at any angle Everything is designed to be printed without supports. Normal PLA in your color of choice is all you need.For my project, I used these libraries: u8g2 by Oliver, elapsedMillis by Paul Stoffregen, and HTTPClient by Markus Sattler, which comes with the Espressif ESP32 platform. Everything else either comes with the Arduino library or the ESP32 platform in PlatformIO. The LR100 series of wire length counter products are designed to be used to create a benchtop rewinding station or can be used as a portable cable length meter. I needed something to cover the space left by the removal of the ugly giant logo on the front of my printer. The zero button also doubles as a reset - hold it down to reboot the board, which is useful for debugging.

This rugged instrument has a wide range of applications where an accurate record of length is required. It is a strong, heavy duty unit for use on calenders, tenters, rolling, ribbon winding textile machinery and almost all other continuous manufacturing processes. But I wanted more than just a dumb counter. With an ESP32 (or ESP8266) and its built-in WiFi, I can actually do something with the data I'm collecting. Using some simple timeout code (explained below), I can determine when printing starts and ends, and send those events as notifications to my phone. In the future, I may add a run-out sensor and notify myself (and pause my printer) when my attention is needed. Interrupts are powerful - sometimes too powerful. A single tap of the zero button could cause the zeroButtonPressed() function to be called 10-20 times, so I added some debounce logic. My optical encoder didn't need it, but YMMV. To develop the code and flash the board, I used the spectacular PlatformIO running on Visual Studio Code, both free. consisting of a number of flip-flops these count a stream of pulses applied to the counter's input. The output is a binary value whose value is equal to the number of pulses received. Synchronous countersA button holder customized for the tiny switch I had, designed to rest between the two shelves inside the bottom enclosure. I used a soldering iron to "glue" the switch to the holder; see the prior step for a photo. You can position a de-reeler just before the wire length counter. The durable de-reeler simplifies the operation of pulling wire and cable neatly from your wire spools. Measuring the movement of filament also let's me know when printing has started and when it has stopped. The LR100-1410 or LR100-1420 are the wire length counter part numbers. LR100-1410 is the wire length counter with footage units and measures in feet and inches. The LR100-1420 is the metric wire length counter and measures in meters with 10 centimeter increments. We have a combined length measuring device that measures in both feet and meters. These length counters have optional Urethane coated measuring wheels available to improve measurements of bare metal products. have a cascade layout of flip-flops in a ring so that the output of the last is fed into the input of the first. Mechanical counters