I’ve recently released version 3 of the talking scale software for the 328-based Arduino and HX711. For those playing catch-up, the original blog is Here, software version 2.0 is Here and the project page is Here.
Version 3 introduces some major bug fixes. I’ve been using the scale for its intended purpose (measuring stylus tracking force) for some time. One particular annoyance was the scale’s tendency to read minus figures at random or to give inaccurate readings. It also appeared that the scale wasn’t calibrating correctly.
This update includes a better function to translate the numbers into speech, borrowed from the Talkie Voltmeter example code. This function can handle any positive or negative whole number up to a million, so the scale software can now be easily adapted to suit hardware with much larger load cells, or multiple cells wired in series for greater weigh capacity.
The calibration issues were caused by the placement of the tare function. This function is now called during setup, rather than inside the loop. There was also a bug in the loop where a statement was used to detect whether the scale had been calibrated, which is no-longer needed and has been removed.
Finally, version 3 outputs key data to the serial console for use in debugging and of course to allow scale values to be recorded.
The updated source code can be downloaded Here. The next update to this project will likely be hardware-related, as I plan to install a miniature amplifier to boost the volume of the scale’s speaker, as well as to correct an issue whereby the reactive load of the speaker could cause damage to the Arduino by being directly wired to one of its digital pins.