Additional documentation and build log can be found on the hackaday.io project page for the SAO Digital Multimeter
- Resistance measurement and LED test (including continuity test with a buzzer)
- SAO Input voltage measurement
- SAO GPIO voltage measurement
- I2C info (WIP)
This is designed to run CircuitPython and there is a custom build with the needed libraries included, and meaningful pin names for easier development.
A binary build of this is included under firmware/firmware.uf2 and the application code (code.py) and resource files are also in the firmware folder.
- Connect the SAO DMM to a computer usig a USB-C cable and hold down the
Bootbutton, when pressing theResetbutton. - A new drive should show up called
RPI-RP2, and you simply copy thefirmware.uf2file to this drive. - When the copy is done, the device will disconnect and reboot.
- A new drive will show up named
CIRCUITPY, and here you need to copy the remaining files in thefirmwarefolder to the root folder of theCIRCUITPYdevice. - The device will not disconnect, but will do one or more reboots, and after that, you are done.
During this, you might be asked or be blocked by your operating system, as sometimes you will need to verify access to new, unknown devices.
The case and all the button caps, the main knob, and internal spacers to make sure everything sits correctly are designed to be 3D printed with a regular consumer printer. They have been tweaked to be printable with a 0.4mm nozzle, but using a smaller one (eg. 0.2mm) will allow you to use thinner layers, at least in some places, to get a smoother top finnish (top of main knob and top of button caps really benefit from that).
There are also files for a set of 3D printable probes, that are designed to be assembled without any tools, sandwitched around a thin probe wire soldered to a P100-B1 pogo pin for the tip.
There is a .3mf file in the case folder with a project for BambuLab printers, including 5 plates, one for each color needed.
To open the project, you will need to install a recent nightly build (og v9 or newer when released), KiCad v8 or earlier won't open this design directly.
Electronics schematics as a PDF file is also included for reference.
The hardware design (both electronics and 3D designs) of the main branch of this repository is released under the following license:
- the "Creative Commons Attribution-ShareAlike 4.0 International License" (CC BY-SA 4.0) full text of this license is included in the LICENSE file and a copy can also be found at http://creativecommons.org/licenses/by-sa/4.0/
The CircuitPython firmware (including the python application code) is released under the MIT license with smaller dependencies under other licenses as detailed in its LICENSE and LICENSE_MicroPython files.