It works. It is also too big.
Part five. HC-01 is running in a real humidor: 522 logged samples, agreement with an independent hygrometer, and one closed control loop.
· 6 min read
hc-01
7 posts
The probe said OPEN. The display was working.
Part four. My J5 continuity probe reported OPEN on a board whose display was provably working, and a bring-up flag shipped on the demo unit.
· 6 min read
The annular-ring fix held: five of five boards work
Part three. Same design, one inverted flag put back, a different assembler. Five of five rev E boards flashed, drove the display and read the sensor.
· 8 min read
We corrected 3.0 mm to 3.175 mm. The calipers read 2.925.
Our spec said 1/8 inch Baltic birch is 3.175 mm. Correct arithmetic on a wrong label. The stock measured 2.925, and the groove was built on the error.
· 6 min read
We told the fab the missing annular rings were intentional. They weren't.
Part two. The fab asked about one thing before building. We said it was deliberate. It was a parser bug, and it explains the open display headers.
· 8 min read
Custom PCB fabrication: three of five boards arrived dead
Three of five boards arrived dead and two had open joints. Test points found where power stopped, and later showed the open joints were our fault.
· 6 min read
From jumper wires to a custom PCB: building the HC-01 humidor controller
An ESP32 rat's nest became a four-revision custom board. The most expensive mistake was a sensor we never actually measured.
· 4 min read