Hardware Overview

Hardware Overview

Hardware components and connections for the Smart Sit-Stand Desk Controller.

🔌 Core Components

Primary Controller

• Raspberry Pi Pico W - Main microcontroller with WiFi

Motor Control System

• BTS7960B H-Bridge - Motor driver module
• 37GB555 Geared Motor - 12V 180RPM DC motor with encoder

Sensor System

• ACS712-30A - Current sensor module
• ADXL345 - 3-axis accelerometer

User Interface

• SH1106 OLED - 128x64 monochrome display
• KY-040 Rotary Encoder - 360° rotary encoder with button (1x UI navigation)
• KY-040 Rotary Encoder - 360° rotary encoder (1x motor position feedback)
• Tactile Buttons - Push buttons for controls (5x)

Additional Components

• 12V Power Adapter - AC to DC power supply
• LM2596 Buck Converter - DC-DC step down module
• Buzzer - Piezo buzzer (PWM driven)
• Vibration Motor - Coin vibration motor 3V
• Connection Wires - For linking components
• 3D Printed Enclosures - Custom housings and mounts (CAD files available)

🔗 Pin Assignments

GPIO	Function	Component	Notes
0	PWM	H-Bridge R_PWM	Motor forward
1	PWM	H-Bridge L_PWM	Motor reverse
4	I2C SDA	OLED Display	I2C0 Bus
5	I2C SCL	OLED Display	I2C0 Bus
6	I2C SDA	Accelerometer	I2C1 Bus
7	I2C SCL	Accelerometer	I2C1 Bus
9	Digital	Preset Button 1	Internal pull-up
10	Digital	Preset Button 2	Internal pull-up
11	Digital	Preset Button 3	Internal pull-up
13	Digital	UI Encoder SW	Button switch (right encoder)
14	Digital	UI Encoder DT	Data signal (right encoder)
15	Digital	UI Encoder CLK	Clock signal (right encoder)
16	Digital	Vibration Motor	Output
20	Digital	Position Enc CLK	Motor encoder (left encoder)
21	Digital	Position Enc DT	Motor encoder (left encoder)
22	PWM	Buzzer	Audio feedback
26	Digital	Down Button	Motor control
27	Digital	Up Button	Motor control
28	ADC	Current Sensor	Analog input

⚡ Power Configuration

Power Rails:
├── 12V (Motor Power)
│   └── Linear Actuator (via H-Bridge)
│
├── 3.3V (All Electronics)
│   ├── Raspberry Pi Pico W
│   ├── H-Bridge Control Logic
│   ├── OLED Display (SH1106)
│   ├── Accelerometer (ADXL345)
│   ├── Current Sensor (ACS712)
│   ├── Rotary Encoders
│   ├── Tactile Buttons
│   ├── Buzzer
│   └── Vibration Motor
│
└── GND (Common Ground)
    └── All components share common ground

🔌 Connection Summary

I2C Bus Configuration

I2C0 (Display):          I2C1 (Sensors):
GPIO 4 (SDA) ──── OLED   GPIO 6 (SDA) ──── ADXL345
GPIO 5 (SCL) ──── OLED   GPIO 7 (SCL) ──── ADXL345

Motor Control

GPIO 0 → H-Bridge R_PWM (Forward)
GPIO 1 → H-Bridge L_PWM (Reverse)
GPIO 20 → Position Encoder CLK
GPIO 21 → Position Encoder DT
GPIO 28 → Current Sensor Output

User Interface

GPIO 13 → UI Encoder Button (right encoder)
GPIO 14 → UI Encoder DT (right encoder)
GPIO 15 → UI Encoder CLK (right encoder)
GPIO 26 → Down Button
GPIO 27 → Up Button
GPIO 9/10/11 → Preset Buttons 1/2/3

Note: All buttons use the Pico W's internal pull-up resistors - no external resistors needed.

Encoder Configuration:

• Left Encoder: Position feedback only (GPIO 20/21)
• Right Encoder: UI navigation with button (GPIO 13/14/15)