IT'S ALIVE (again)

A project log for HydraMETER

Open-source multimeter with some unique features

john-duffyJohn Duffy 10/27/2023 at 20:550 Comments

This is like, kind of working!!

I have the first prototype board assembled, and have the paths for voltage, ohms, and current all up and running.  Haven't written most of the software, made the display, calibrated anything, or put the thing in a case yet, but the measurement itself looks like it's working!

I am excited. Whoo.

Got boards back from fab a little over a week ago, thank you to PCBWay for supplying free boards for the project.  Normally wouldn't take free stuff just to advertise for a company, but this is one of a few companies I've been using for years now and happy with their services.  I've recommended them for prototypes and quick-turn boards for years, even without any incentive. 

Boards looked good, funny enough this is my first time ever making slots, but no issues with that.  During assembly, inevitably a couple issues popped up, I'd given a 14-pin SOIC a 16-pin footprint.  D'oh.  Soldering one side down and a few bodge wires to the other side got that working though.  Later on realized that one of the pins on the output shift registers should have been pulled high but was low.  Unfortunately these were tiny DHVQFN packages, but some bodge soldering involving squinting that will probably make my eyes stop working six months sooner, later, and we've got a working board.

Everything went concerning smooth on power up, using the software from the breadboard just read out from the ADC and controlled the PGA out of the box, and my first attempt at controlling the shift registers, gain stage, and ohms sections all worked on the first try with literally zero debugging ... so surely there's probably some horrific, underlying issue with the whole thing that will keep it from ever working.  Either way I'll enjoy the good times before we get to that.

Now to start putting together the case and display, and start on the real software