Hardware & Pinout

Hardware & Pinout Reference

ESP-MeteoPlaneRadar is specifically engineered for the Waveshare ESP32-S3-Touch-LCD-2.1 development board. This board integrates a high-performance ESP32-S3 module, a round 2.1-inch 480x480 IPS display with ST7701 controller, capacitive touch via CST820, an I2C I/O expander, real-time clock, and IMU sensor.

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📐 Board Overview & Specifications

Component	Specification	Description
SoC	Espressif ESP32-S3-WROOM-1	Dual-core 32-bit Xtensa LX7 @ 240 MHz
Flash	16 MB SPI Flash	High-capacity flash partitioned for dual 3.2MB OTA apps + NVS
PSRAM	8 MB Octal-SPI (OPI) PSRAM	High-speed memory used for zero-copy double-buffered framebuffers and ADS-B caching
Display	2.1-inch Round IPS LCD	480 × 480 resolution, full 16-bit 65K colors (RGB565), wide viewing angles
Display Driver	Sitronix ST7701	3-wire SPI for command setup + 16-bit parallel RGB interface for high-speed video DMA
Touchscreen	Hynitron CST820	Capacitive touch controller with gesture and multi-point support
I/O Expander	TCA9554PWR	I2C GPIO expander driving LCD reset, touch reset, LCD chip select, and panel power
RTC	NXP PCF85063	Ultra-low power real-time clock (I2C)
IMU	QST QMI8658	6-axis inertial measurement unit (accelerometer + gyroscope)
Connectivity	2.4 GHz Wi-Fi (802.11 b/g/n) & BLE 5.0	Integrated PCB antenna
Power	5V DC via USB-C or headers	Typical operating current: 280–420 mA

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🔌 Pinout & Hardware Connections

1. Display Interface (ST7701)

The ST7701 utilizes a hybrid interface: SPI is used during boot initialization to configure registers, while a dedicated 16-bit RGB DMA bus continuously scans out pixels directly from ESP32-S3 PSRAM.

SPI Configuration Pins

Function	GPIO	Notes
LCD_CLK	GPIO 2	Serial clock for ST7701 command register initialization
LCD_MOSI	GPIO 1	Serial data out for ST7701 commands
LCD_CS	EXIO 3	Chip Select driven via TCA9554 I/O Expander
LCD_RST	EXIO 1	Hardware reset driven via TCA9554 I/O Expander
LCD_PWR	EXIO 8	Display power rail control via TCA9554

16-Bit RGB Interface (esp_lcd_panel_rgb)

Signal	GPIO	Description
RGB_HSYNC	GPIO 38	Horizontal sync signal
RGB_VSYNC	GPIO 39	Vertical sync signal (VSYNC interrupt driver)
RGB_DE	GPIO 40	Data enable signal
RGB_PCLK	GPIO 41	Pixel clock (configured to 8 MHz for PSRAM bandwidth optimization)
RGB_D0 .. RGB_D4 (Blue)	5, 45, 48, 47, 21	Blue 5-bit color bus
RGB_D5 .. RGB_D10 (Green)	14, 13, 12, 11, 10, 9	Green 6-bit color bus
RGB_D11 .. RGB_D15 (Red)	46, 3, 8, 18, 17	Red 5-bit color bus

Backlight Control

Function	GPIO	Configuration
LCD_BL	GPIO 6	Hardware LEDC PWM, 20 kHz frequency, 10-bit resolution (0–100% duty cycle)

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2. I2C Bus & Peripherals

The I2C bus operates at 400 kHz (Wire interface) and connects all on-board digital sensors and controllers.

Peripheral	I2C 7-bit Address	Interrupt Pin / Extra Lines
TCA9554PWR (I/O Expander)	0x20	Controls board reset lines and LCD power
CST820 (Capacitive Touch)	0x15	GPIO 16 (Interrupt), EXIO 2 (Reset)
PCF85063 (RTC)	0x51	Backup battery powered real-time clock
QMI8658 (IMU 6-Axis)	0x6B	Accelerometer & Gyroscope

TCA9554 I/O Expander Pin Assignment

• EXIO 1: LCD_RST (Active LOW panel reset)
• EXIO 2: TOUCH_RST (Active LOW touch reset)
• EXIO 3: LCD_CS (ST7701 chip select)
• EXIO 8: LCD_PWR (Power regulator enable for the panel)

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⚡ Power Considerations

1. USB-C Power: Use a stable 5V / 1A or higher power adapter and a good quality USB-C cable. Low voltage or noisy USB ports can cause Wi-Fi brownouts.
2. Current Draw:
   • Idle screen on (100% brightness): ~280 mA
   • Wi-Fi transmission burst + radar download: ~380–430 mA
   • Night mode / dimmed backlight: ~150–200 mA
3. Thermal Management: The ESP32-S3 runs cool under normal operation. If installed inside an enclosure or 3D printed housing, ensure ventilation slots are provided around the PCB.