d near the top). 2. Display: 0.96-inch / 1.3-inch SH1106 I2C OLED Display header (positioned directly above the main keyboard). 3. Power: USB-C connector with necessary 5V to 3.3V power regulation (LDO) and decoupling capacitors (100uF electrolytic + 0.1uF ceramic near ESP32 3V3/GND) to prevent Wi-Fi brownout resets. ASYMMETRICAL MATRIX KEYPAD LAYOUT: Arrange tactile push buttons (6x6mm or 12x12mm through-hole/SMD) into two distinct grid sections: Section A (Upper Wide Grid - 6 Columns x 3 Rows): - 18 tactile switches total. - Matrix Wiring: 6 Column lines (Col 1 to Col 6) x 3 Row lines (Row 1 to Row 3). - Pitch/Spacing: Standard 12mm to 15mm center-to-center button spacing. Section B (Lower Narrow Grid - 5 Columns x 4 Rows): - 20 tactile switches total. - Matrix Wiring: Reuses 5 Column lines (Col 1 to Col 5) x 4 new Row lines (Row 4 to Row 7). - Position: Centered horizontally beneath Section A. BOARD SPECIFICATIONS: - Board Type: 2-layer PCB, FR4 material. - Connectors: Breakout headers for I2C (SCL=GPIO18, SDA=GPIO21). - Traces: Min 0.25mm trace width, thicker power traces (0.5mm+ for 5V/3V3/GND). - Ground Plane: Top and Bottom layer copper fill for GND.