Wireless CNC Pendant Implemented With ESP-NOW

As a fervent fan of twiddly and twirly widgets and tactile buttons in a device’s user interface, [Steve M Potter] created a remote control (pendant) for his CNC machine, which he explains in a recent video that’s also linked down below. In addition to all the tactile goodness, what is perhaps most interesting about this controller is that it uses Espressif’s ESP-NOW protocol. This still uses the same 2.4 GHz as WiFi would, but uses a system more akin to the pairing of a wireless mouse or keyboard.

Advantages of ESP-NOW include the lower power usage, longer range, no requirement for a router and WiFi SSID & password. As far as latency goes, [Steve] measured a round-trip latency of 2.4 ms, which is fast enough for this purpose. Since it does control a potentially dangerous machine, all transmissions are acknowledged and re-transmitted at higher power if needed.

The lower power usage means that the pendant will last a lot longer on a single charge from the 18650 Li-ion cell, while ESP-NOW’s fixed address pairing saves time when turning the pendant on. Meanwhile, on the CNC side, another ESP32 acts as the receiving end for commands, although theoretically an ESP8266 could be used as well, if size or power was a concern there.

As for the transparent enclosure? It’s to make it easier to show it off to interested folk, apparently.

6 thoughts on “Wireless CNC Pendant Implemented With ESP-NOW

  1. It’s a bit fugly. Plus, I really think a wired solution is better, not least to have a reliable E-Stop. You’re never going to be far from the machine.

    However, as an exercise in using ESP-NOW it’s excellent.

    1. If my fugly pendant is switched on, I can halt or pause the machine as fast as my hand can hit the button. Faster than stepping over to the controller box and hitting the Estop switch. If it is on but not connected for some reason it lets you know with beeps, lights, and an error message. If it is off, thanks to ESP-Now, there is less than a half second delay before it boots up and connects. For “Pause” I implement the “Door” realtime grbl command, which is set to halt feed, stop the spindle and lift it quickly out of the wood.

      1. Finally! Someone who understands my needs! How do you hang it from your neck? Is there a standard or dual time zone complication so i can wear it on the regular with the rest of my clocks? The zone for washed up rappers turned CNC machinists has largely been ignored….until now!

  2. “Since it does control a potentially dangerous machine, all transmissions are acknowledged and re-transmitted at higher power if needed.”

    I wouldn’t consider this enough – the host should issue emergency stop if transmissions stop for e.g. 100 ms.

  3. I’d not want to have this as my only emergency stop, but I’d guess He’s got a physical button to kill power anyway.
    It does seem a bit unwieldy to me from an ergonomics perspective, I’d much prefer something like a game controller.

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