GPIO Planner
Reserve safe pins before wiring sensors, relays, LEDs, and buses.
Maker Toolbox
Fast calculators for real ESP32 decisions.
Page sections
Plan pins, size resistors, estimate battery life, check voltage dividers, decode resistor bands, and calculate PWM and ADC values — all in one place.
LED Resistor Calculator
Find a safe series resistor for a simple indicator LED.
Voltage Divider Calculator
Estimate output voltage from two resistors.
Battery Life Calculator
Quickly estimate runtime from capacity and current draw.
PWM Calculator
Plan LED dimming and motor speed. Calculate frequency, period, and on-time from duty cycle.
ADC Calculator
Convert raw ADC readings to approximate voltage. ESP32 ADC is 12-bit at 3.3V reference.
Power Consumption Calculator
Estimate average current across active and deep sleep phases in a duty-cycle project.
Resistor Color Code
Decode 4-band resistors and find their value.
ESP32 Pinout Explorer
GPIO 21/22 = I2C default. GPIO 18/19/23/5 = SPI default. GPIO 6-11 = flash, never use. GPIO 34/35/36/39 = input-only.
Full pinout ->UART Reference
UART0 TX=GPIO1, RX=GPIO3 (USB). UART2 TX=GPIO17, RX=GPIO16 (free). Monitor baud: 115200. Logic level: 3.3V only.
ReferenceWiFi RSSI Reference
-30 to -50 dBm = Excellent. -50 to -70 = Good/Fair. Below -80 = move closer. Read via WiFi.RSSI().
ReferenceSPI Reference
SCK=GPIO18, MOSI=GPIO23, MISO=GPIO19, CS=GPIO5 (one per device). Multiple devices share SCK/MOSI/MISO.
ReferenceI2C Address Reference
SSD1306=0x3C, BME280=0x76/77, MPU-6050=0x68/69. SDA=GPIO21, SCL=GPIO22 default.
OLED guide ->Safe GPIO Quick List
Beginner-safe pins: 4, 5, 18, 19, 21, 22, 23. Avoid 6-11 (flash) and be careful with 0, 2, 12, 15 (boot strap).
Mission 01 ->