Embedded Files
Project Overview
Our project took inspiration from an everyday problem we sought to fix: adjusting blind positioning remotely. The system receives signals remotely via Bluetooth through the microcontroller and utilizes a DC motor to turn clockwise or counterclockwise, depending on whether the blinds are desired to be open or closed. The system is designed to replace the traditional tilt wand of the very commonly used vinyl blinds.
In-Depth Breakdown
The design behind the PCB centered on a few design constraints:
1. Compute
Microcontroller: ESP32-S2-SOLO-N4
Recieves signals via bluetooth and transmits to control the motor driver
2. Power
12 V Wall Power through 2 x 5.5 mm barrel connector to power the motors
5V to 3.3V LDO to program the ESP32 through USB-C
Fuse and physical cutoff switch implementation for motor protection
3. Actuation
Bipolar stepper DC motor
Connects to blinds rod to open and close blinds
BOM
Schematic
Layout
3D view of the PCB
Enclosure for our final product
Areas for Improvement and Lessons Learned
Challenges:
LDO current capacity was 250 mA, while the ESP32 required 500 mA minimum
USB-C footprint is missing thermal relief, making the assembly process difficult
ESP 32 was shorted when using a heat gun and solder paste to solder
Wrong orders of bootstrap capacitor & resistor
Lack of connection between 12V wall power and ESP, preventing power delivery without USB-C
Successes:
New PCB design, soldering and debugging techniques learned
Have a 3D printed enclosure
Debugging Efforts:
Cutting traces to test LDO to ESP connection -> identified ESP current draw not met by LDO
Connected the ESP straight to the external power supply to check if code could still be added
To Improve:
Add LED and test points for easier debugging.
Add thermal relief for all grounded pads.
Check the current and voltage rating in the datasheets more carefully.
Make sure that the values of the resistors and capacitors in the BOM are correct.
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