With parts needed for the scale integration coming in this week, this provided a good opportunity to get my hands dirty on this component of our design. These include the Arduino Mega, 2 ArduCam cameras, a physical scale, the ESP wifi chip, and HX711 amplifiers. I am still waiting on the RPIs to integrate with the ArduCam cameras; to recap from last week, I plan on trying 2 different implementations and seeing which method works better.
For now, I will emphasize our original implementation plan: to remove the casing on the scale, disconnect the load cell wiring from the original Wheatstone arrangement, run the 4 load cell wires into the amplifier, which would then feed into the Arduino and subsequently the ESP. From there, the ESP would just need to generate HTTP requests as I have scripted in the code I wrote last week. The factors that I am wary of include not damaging any sensitive equipment in the process of rewiring the scale. I plan on snipping the wires from the PCB in the scale as opposed to desoldering them because the last thing I want is there to be frayed copper at the ends of these connections. I hope Techspark has some heat-shrinking plastic casings that I can keep around the connections I need to resolder so that the bare ends are preserved somewhat. If any of these connections are challenged or compromised, the scale cannot be used, so that is a consideration I have in mind when working on this. Here is an example of the material (in black):
Figuring out the wiring between the amplifier and load cell was also a bit nonintuitive for me. Here is a sample diagram that I plan on using to ensure the reconnections are going to the right places. To keep things simple, red will match with red, blue with blue (these are the wires that “talk” to each other to get the total aggregate weight from all 4 load cells), and I’ll send the white wires to the amplifier. I adapted this from the documentation on the load cells:
I have slowed down work on our web application; I think it is up to a point where all the basic functionality is present, and as a group, we will have to build the rest of the application around the hardware we will implement. One theme readers may observe across the group this week is a shift towards implementation hardware as the backend frameworks are in place.
In parallel, I will have conversations with the group to build an idea of what we want to show off for the upcoming interim demo. Overall, we are on track with schedule but we recognize that the next few weeks are essential to the completion of this project.