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The ANX dev module uses a logical GPIO numbering scheme where each physical pin is identified by a sequential number printed on the silkscreen, and each GPIO has a corresponding logical number used in firmware calls. All I/O pins operate at 3.3 V logic — they are not 5 V tolerant. The two 20-pin headers, P1 on the left side and P2 on the right side, give you access to all 40 pins. Pin 1 on each header is marked with a square pad and a triangle on the silkscreen for easy orientation.
Never apply more than 3.3 V to any GPIO, ADC, UART, I2C, SPI, or PWM pin. Exceeding this voltage permanently damages the microcontroller. Use a level shifter when interfacing with 5 V peripherals.

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Pin Header Layout

The module exposes two parallel 20-pin headers spaced 0.1 inches (2.54 mm) apart — the standard breadboard pitch. P1 runs along the left edge of the board and P2 runs along the right edge. Both headers are numbered top to bottom with pin 1 closest to the USB-C connector.

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P1 Header — Left Side

The P1 header carries power rails, the primary UART, I2C bus 0, SPI bus 0, and general-purpose GPIO.

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P2 Header — Right Side

The P2 header carries the 5 V USB input rail, the 8-channel ADC, PWM outputs, the secondary UART, I2C bus 1, the hardware reset line, and additional ground references.

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Electrical Limits

Stay within these absolute maximum ratings to avoid damaging the microcontroller:

GPIO Voltage

Maximum 3.3 V on any I/O pin. The pins are not 5 V tolerant under any condition.

Per-Pin Current

Maximum 12 mA source or sink per individual GPIO pin.

Total GPIO Current

Maximum 50 mA combined across all GPIO pins simultaneously.

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Reserved Pins

GPIO34 through GPIO39 are routed internally to the wireless radio subsystem (Wi-Fi and BLE). These pins are not exposed on the headers and must not be driven or read through external connections. Attempting to configure them as user GPIO in firmware has no effect and may interfere with wireless operation.
To control GPIO pins programmatically, use the anx_gpio_set_direction, anx_gpio_write, and anx_gpio_read functions from the ANX SDK. See the Peripherals guide for interface-specific examples, and the ANX SDK API Reference for the complete GPIO function signatures.