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Hey Pono - finally found a use for the ESP32

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RideTheGlide:
All that fancy hardware baked in - WiFi, BT, dual processing, etc...

I am using it to take some simple commands to drive the DACs move a couple of galvos only a short distance. The galvos take +5 and -5 and I grounded the -5 inputs and just drive the +5, but only up to 3.3v. The guy I am doing it for develops commercial microscopes and this is to point a laser around for some kind of spectral processing. It doesn't have to move the mirrors far at all. And he actually has money - a part time gig that pays. Anyway, I will probably get 12 bit 5v DACs mounted on a PCB for a little more range and precision if he moves forward with it. Seems likely since the prototype can do what he was hoping. He picked up some cheap imported galvos and driving them with a microcontroller the cost of it compared to the higher end stuff is amazingly cheap. Seems to have pretty good accuracy and stability.

surfcowboy:
Love the geekery. I want my retirement to be goofing off with this kind of stuff. Nothing at your level but I love hardware so much. Computers moving things fascinates me.

I design and product manage applications but there’s something about physical objects that moves me.

PonoBill:
Look at the MCP4725. Cheap and precise, sparkfun has a breakout board with one mounted for five bucks. I2C controlled, should be a snap to control with a ESP32. And as always, sparkfun has sample code for free. https://learn.sparkfun.com/tutorials/mcp4725-digital-to-analog-converter-hookup-guide

I built the height sensors and controller for my GMC moho with ESP32's. The electronics are done (sort of), now I just need to take them back to Hood River and mount them. I bailed on the IR sensors, I'm just using pots with a jointed arm that I plan to mount on the arms that transfer the air bag pressure to the bogie wheels.  The two sensor talk to a third ESP32 that shows the height of each side. I can select the desired height with pushbuttons or just choose presets for either side. I don't know how the aftermarket compressor that is currently installed controls the air bags on either side, so I'm not sure what the control system will be like but I have the basics working (relays clicking) with a range of about 50 feet which should be plenty. I got wrapped around the axle trying to manage interference between the three radios and finally realized it didn't matter.

I'm sure I'm going to have to redo all this, but at least I know it will work in principle. Kind of a lot of work to avoid running a few wires, but hey--geek.

RideTheGlide:
Funny you mention the 4725. I was going to do that with the Arduino. Made a wiring mistake and smoked them. Only briefly touched 15v. But I had them working; sending commands to the Arduino and measuring the voltage out and it was fine; I would have more range at much higher resolution if I do that again. It was a pain to wire on a tiny breadboard. It's only a little more in parts to get the full -5 and +5 for full range, but if it isn't needed why bother? That axiom may hold true for the DACs also - if 3.3v is adequate, why bother with 5? The level just pushes other logic. There is a standard for galvos that specifies a hardware interface using +5 and -5, but the controllers/motors actually use +15/-15. It may be useful to have BT and WiFi. OTOH, if this gets done in bulk, a MCP4822 on a PCB will probably be the way to go. A single cheap chip will do both channels.

PonoBill:
That's exactly why I'd rather have them on a breakout board. The pins on dinky ICs, even ones that aren't surface mount, aren't spaced for a breadboard. For prototyping or a limited quantity build the breakout boards are far more practical--they take a standard breadboard header. If you went into production and needed to make PC boards and a compact finished version you can graft the eagle files from the breakout into your PCB design. I hardly bother with discrete components for projects, the typical breakout from Adafruit or Sparkfun cost a couple of bucks more than the naked component. Why bother. Especially when they include hookup directions, eagle files, and sample code for that five bucks vs. three bucks. The 4735 breakout board is on backorder but they are preparing a run of 300. They'll probably go quickly, they've been out of stock for a while.

I used a bare DAC8512 last time I needed one, got five modified surface mount for 20 bucks on ebay. Good thing, I smoked three of them. And then my brilliant idea for a "any input voltage you want" LED driver didn't work anyway, though I could have sold it as a way to trigger epilepsy.

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