My recent experience with the Bald SENSE sensor feather wing project reminded me that time is often our most valuable resource. This video documents the journey that has taught me crucial lessons about design, assembly, and the value of turnkey PCB assembly services. See what went right and what went wrong, and how I ultimately brought this project back to life with the help of MacroFab.
The Origins of Bald SENSE
A few years ago, I set out to build a custom environmental sensor platform for my new lab and studio. The goal was simple: capture data on temperature, humidity, light, and sound and eventually integrate it with Home Assistant (or some other IoT platform.) I chose the Adafruit Feather form factor due to its compact size and versatility. Plus, I had a bunch of them already. However, they all had different feature sets. For example, some had a radio or micro SD card socket, but none had both.
The first version of the Bald SENSE design featured sensors I already had breakout boards. One feature I almost did not add is the DS3231 RTC. Many (32-bit) microcontrollers have one built-in, but Feather boards rarely have the necessary 32 kHz crystal or pins exposed to clock them.
The DIY Assembly Challenge
As with many of my electronics projects, I assembled the first board myself. My DIY process involves using a polyimide (Kapton) stencil, which works well for larger components but struggles with fine-pitched parts like QFNs. While cost-effective, the Bald Pick-and-Place machine (aka, me) was slow and prone to errors. The reflow process was another challenge—despite having Open Vapors, a custom solid-state relay-based controller, I spent a lot of time on rework.
After at least 40 hours of effort, I managed to get two boards functional, but not without discovering “some” mistakes along the way. The struggle to assemble these boards myself was a valuable lesson in the limitations of DIY processes.
MacroFab: A Turnkey Solution
Years ago, I experimented with custom PCB design by creating a triangle-shaped Arduino board called Pyramiduino, which I paid for MacroFab services to have assembled for me. When they offered to sponsor this video and build the Bald SENSE boards, I jumped at the chance. I was determined to avoid the pitfalls of my previous DIY assembly experience!
The process began with cleaning up the schematic and ensuring every detail was correct—especially the micro SD card socket. I converted the design to a four-layer board to improve power and ground distribution and uploaded the design files to MacroFab’s platform. Their tools made it easy to refine the bill of materials, check for component availability, and get an automated quote. The entire experience was smooth and hassle-free. Well, except for the hurricane that delayed the final delivery by a day.
Bald SENSE Turn-On
When the assembled boards arrived, I was delighted that everything looked fantastic. Assembly issues were none, so I quickly got to work soldering headers and connecting the board to a Feather S3 graciously provided by Seon at Unexpected Maker. Using CircuitPython, I got the sensors, SD card, and RTC working in less than a day. The only hiccup was with the PDM microphone, which CircuitPython does not yet support on the ESP32. Regardless, I quickly added Wi-Fi, MQTT, and deep sleep support. Those features meant I was ready to start collecting data.
Testing Bald SENSE in the Real World
I placed the Bald SENSE board in a plastic container and set it up in my garden. I immediately encountered a problem: the ESP32-S3 wasn’t connecting to my MQTT broker. A quick scan with a Flipper Zero (and Wi-Fi add-on from Electronic Cats) revealed that it was trying to connect to the wrong access point. Once corrected, data started flowing, but the temperature readings were skewed by direct sunlight—something I should have anticipated.
Moving the device to a shady spot and reducing the data collection interval to 10 minutes solved these issues, and I began logging meaningful data. Over the next few days, I saw interesting patterns emerge, like ADC drift at high temperatures, which I’ll explore further in a future future. This successful testing phase brought a sense of relief and satisfaction, knowing that the Bald SENSE was functioning as intended.
Lessons Learned and a Path Forward
This project reinforced the value of turnkey assembly services, especially for boards with tiny footprints like Bald SENSE. While I enjoy the DIY approach, MacroFab’s turnkey assembly saved me countless hours and provided a level of precision that my in-house setup could not match.
For anyone considering their own PCB projects, I highly recommend trying MacroFab. Their tools and services make it easy to bring your designs to life, whether you’re a hobbyist or a seasoned engineer like me.
As for Bald SENSE, the journey is far from over. With a functional sensor platform in hand, I am excited to see what kind of data I can gather and how I can use it to improve my garden—and maybe even my entire home automation system. The future of the Bald SENSE project is filled with possibilities, and I look forward to sharing more updates on this exciting journey!
If you want to try out MacroFab’s services for your projects, use this referral link to get started today!
