I am looking for some advice on a project that I am working on that utilizes a load cell configuration for inventory management purposes. My goal is to read in a value from a loadcell which is monitoring a bin full of hardware, and divide it by the weight of a single hardware item to get the quantity in the bin and then display it on an LCD.
I have done projects in the past utilizing an Arduino uno, HX711, and loadcell. These projects required code to calibrate the loadcell and to read in the data from the load cell to be manipulated. So I am wondering if there is any way that I can take advantage of the Open Scale processor/or the QWII scale to help me simplify my project. In the case that I have to use four load cells to read in a single value, could I connect the Open Scale to my Arduino rather than reading it straight into my computer? Any information regarding how I can most easily accomplish this project would be greatly appreciated.
Yes the Qwiic system will help simplify your project in terms of no need to solder.
could I connect the Open Scale to my Arduino rather than reading it straight into my computer?
Yes you can. There is a header breakout to use with a Serial to USB FTDI breakout board, but you can use those Serial lines with a regular Arduino as well.
Any information regarding how I can most easily accomplish this project would be greatly appreciated
Unfortunately, we can't offer direct code consultation or project consultation. However, a great resource to get you started would be the [[Hookup Guide](https://learn.sparkfun.com/tutorials/openscale-applications-and-hookup-guide#overview) for the OpenScale.
Thanks for your quick response Brian. My last question is, if I were trying to use 4 load cells to read out the weight of a single object could I accomplish this more easily with the Open Scale or the QWII.
With either one you choose, you’ll need multiple readers. With the Qwiic system it will be easier for wiring, but you’ll need multiple controllers or I2C ports. With the OpenScale you’ll need a device capable of multiple USB ports. I’m not sure which of these will suit your situation.
It would seem you have three options: OpenScale, QwiicScale, HX711. Whichever one you choose you will need one per bin. The HX711 is the less expensive option, but you will need (at least) one controller (i.e. Arduino, rPI, etc.) and a pair of DAT/CLK line for each. That can eat up all your IO on the controller and make the code more complicated. The next least expensive option is the QwiicScale. That would be the ideal case if the I2C address would be adjustable; according to the documentation it is not which makes it not much easier to use in your case than the HX711. The most expensive option is the OpenScale as it contains its own controller. This is the fastest to get you there but to me it would seem that it will eat up a lot of money. I would opt for the HX711 board with a couple of multiplexer ICs (one for DAT and one for CLK) and you could easily string some 8 devices per mux pair using only a few IOs on the controller and the already available code for the HX711 on SFE. The QwiicScale is good, but in my mind it is no much better than the HX711 board and more expensive.
[EDIT] Actually SFE already saw this issue of multiple devices with same I2C addresses and you can link up to eight (8) QwiicScale pretty quickly using the SparkFun Qwiic Mux Breakout. If you need only eight bins, that would be the simplest (and not too expensive option.
Patrick C:
My last question is, if I were trying to use 4 load cells to read out the weight of a single object could I accomplish this more easily with the Open Scale or the QWII.
Can you clarify the part I’ve underlined? If you mean four load cells (or more) on a single platform surface (like a pallet scale with four feet), you only use one scale processor. The load cells are configured electrically parallel, typically using what’s called a [summing card and/or junction box. These often have potentiometers to tune in the slightly different outputs from the cells for a given load though, with good load cells, these errors may be negligible.
Broadly, you’re describing what’s called a counting scale. Usually, a smallish number of parts are hand counted and weighed at high resolution with the result divided by the number of pieces. This is called a sample or sampling and the resulting value is the Average Piece Weight (APW). This APW may be saved to a database on the scale or externally. Of course, there needs to be some mechanism to associate the part number with the APW for later recall next time that part is to be counted. If there are only a few typical parts, there may be buttons like on this coin counting scale: [Coin counting scale
However, a large stockroom will need a more sophisticated solution.
Another challenge it ensuring that you’re getting a truly average representation of the parts. If you happen to sample with a particularly heavy or light set of parts, counting accuracy suffers. Similarly, if you’re parts vary in weight significantly over time due to things like tooling wear or inconsistent plastic molding or a product from multiple vendors, the counts may not shake out right. Like any other statistical sampling, a larger sample gives a better average value but this must be weighed (ha!) against the hassle of hand counting a large number of small parts.](https://changemakerstore.com/ez-60-fast-and-easy-coin-counting-scale.html)](Junction Boxes | Rice Lake Weighing Systems)
