Custom CNC Pendant Application

markz

@MadewithMayo I've got a pendant I've been working on; to contrast the design... the pendant uses a Raspberry Pi Pico W with WiFi, a 3.5" touchscreen LCD, and the RRF Rest interface to communicate. I've got a board being made (2 weeks) that adds Lipo battery support to the Pico so the pendant can be wireless handheld.

I'm planning to put two rotary switches (axis and speed) on the unit as well as one indicator dial for movement - much like a conventional pendant - see here -> https://www.amazon.com/RATTM-MOTOR-Handwheel-Emergency-MITSUBISHI/dp/B07CZ7F3Y3

I'm writing it in MicroPython - but their Pico W port is not quite stable yet.

I've written plenty in Arduino and in my personal opinion it's not a production OS.

Why do it this way?

a) I have three Duet3d systems that I'd like to control and having a wifi pendant lets me walk it around.

b) I hate cables. They get caught on things and have finite lengths and physical failures.

c) Writing a small amount of easily maintained Micropython seems easier than negotiating changes to a PanelDue set of code that's really not designed for my applications (such as a CNC router).

My 2c.

Mark

Nightowl

@markz
I like the sound of that. I was looking at the Duet3 guidance with the conventional pendant, as per your link, but are you saying Arduino isn't the way to go?

Happy New Year

markz

@Nightowl It's just my personal opinion but I'm not a fan of Arduino software.

Arduino hardware is fine but it's very last generation and imho it's designed for hackers who want a quick sensor or monitor. The usual kit is an Atmega 328p - an 8 bit one-core processor with 1K ram and 32K flash at 20MHz.

The Pico W, by comparison, is - a 32 bit dual core (M0+) processor with 256K ram and 2MB of flash at 133MHz with WiFi.

achrn

@markz said in Custom CNC Pendant Application:

The usual kit is an Atmega 328p - an 8 bit one-core processor with 1K ram and 32K flash at 20MHz.

Off topic, but you could look at Teensy 4 - Cortex-M7 at 912MHz with 32 & 64bit hardware fpu, nearly 8MB flash, 1 MB RAM, more timers / hardware peripherals than you can shake a stick at (e.g. 49 different timers, on-chip RTC, quadrature decoders, 8 uarts with FIFOs, CAN Bus, multiple SPI and I2C), but all running withing the Arduino IDE and without the arduino-silly-pin-offset. Not 5V tolerant though. I don't know how well it's supported in/by micropython (but there is some support, google suggests).

Arduino brought into this decade. Very nice.

Downside is the hardware design is literally one-man-band (Paul Stoffregen) but with quite a lot of community support on software. If you want to do something tricky it's a very 'use-the-source' sort of community (though generally helpful - on the forums there's more a sense of 'not sure why you're asking that when you could just read the source / Cortex processor documentation' rather than one of 'RTFSource you cretin')

https://www.pjrc.com/teensy/techspecs.html

I haven't quite got over the learning curve on Pico W yet, and it wasn't helped when the first thing I tried to get my head round the state machines (something teensy doesn't have) with was some neopixel strips, and that turned out to have some flakiness in the supplied libraries.

Nightowl

@markz
Hmm, I appreciate the sentiment but I was thinking more Ford Prefect than Rolls Royce Corniche - and there seems to be a lot of support out there (if not too much!)

As long as it can do the job, and a couple of other little jobs I want it to do, I'll probably (simple) Arduino

dc42

@Nightowl if you are used to programming Arduino, RPi Pico is still a good choice. It costs less than most Arduinos and there is an Arduino port for it.

Nightowl

Sadly, I'm not used to programming anything, @dc42. This would be my first foray into the dark art, except the central heating!

Thank you, though. I'll take a look at it. I'm sure a Google search will bring something up...

EDIT: Just goes to show what I know - I didn't realise RPi Pico is a Raspberry Pi product. Now I understand, but boy do I feel slow!

MadewithMayo

@dc42 would it be possible to change the selector switch on a pendant with a momentary switch? Several rotary encoders have a momentary switch built in and it could be nice to use it to change between settings that way instead.

dc42

@MadewithMayo that would certainly be possible but I think you would also need LEDs or some other way to indicate which mode was currently selected.

BTW the rotary encoder on the pendant that I built my design around is far better than the cheap rotary encoders that have built in push buttons.

MadewithMayo

@dc42 I am breaking the mold a little since this will all end up in a microscope so any LEDs wont be visible anyway and I was hoping to find better encoders but the cnc pendant knobs are a little big. Outside of the cheap ones, it seems that just getting a rotary encoder that had over 400ppr was the next jump but thats a bit excessive for my needs. Maybe i'll regret it, we'll see how long it takes to get this experiment up and running. I really appreciate you filling in the gaps!