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External GPIO Pinmap — Rev 1.1

This page covers the external expansion header pinmap for the XM10 Rev 1.1 board. Eight digital I/O (DIO) pins and four dedicated analog input (ADC) pins are available by default. Any of the eight DIO pins can be dynamically switched to ADC mode at runtime, giving you up to 12 ADC channels total.

For the API (function calls) to use these pins, see External IO API. This page focuses on board pin layout.

Header Location

XM10 Rev 1.1 board — external GPIO header location

Use the photo above to locate the external GPIO header (DIO 8 + ADC 4) on the Rev 1.1 board and to identify which end is pin 1. Refer to the tables below for per-pin functions.

DIO 8 Pins

API Name PCB Label Default Mode Notes
XM_EXT_DIO_1 EXT_GPIO_1 Digital Can be dynamically switched to ADC
XM_EXT_DIO_2 EXT_GPIO_2 Digital Can be dynamically switched to ADC
XM_EXT_DIO_3 EXT_GPIO_3 Digital Can be dynamically switched to ADC
XM_EXT_DIO_4 EXT_GPIO_4 Digital Can be dynamically switched to ADC
XM_EXT_DIO_5 EXT_GPIO_5 Digital Can be dynamically switched to ADC
XM_EXT_DIO_6 EXT_GPIO_6 Digital Can be dynamically switched to ADC
XM_EXT_DIO_7 EXT_GPIO_7 Digital Can be dynamically switched to ADC
XM_EXT_DIO_8 EXT_GPIO_8 Digital Can be dynamically switched to ADC

Electrical specifications: - Input / Output: 3.3 V logic - Internal pull-up / pull-down resistors: supported (select via XM_SetPinMode)

ADC 4 Pins (Fixed)

API Name PCB Label Notes
XM_EXT_ADC_1 EXT_ADC_1 12-bit native (ADC1), analog input only
XM_EXT_ADC_2 EXT_ADC_2 16-bit native (ADC2), analog input only
XM_EXT_ADC_3 EXT_ADC_3 12-bit native (ADC1), analog input only
XM_EXT_ADC_4 EXT_ADC_4 16-bit native (ADC2), analog input only

Electrical specifications: - Input range: 0 – 3.3 V - Resolution: XM_EXT_ADC_1/_3 = 12-bit native (ADC1), XM_EXT_ADC_2/_4 = 16-bit native (ADC2) — function output supports 8/10/12/16-bit selection - Sampling rate: 10 kHz

DIO → ADC Dynamic Switch (8 Additional Channels)

Switching a DIO pin to ADC mode at runtime gives you up to 12 ADC channels. Call XM_SwitchDioToAdc(), then read with XM_AnalogRead(XM_DIO_TO_ADC_PIN(dio)).

API After Switch Original DIO
XM_EXT_ADC_5 DIO 1
XM_EXT_ADC_6 DIO 2
XM_EXT_ADC_7 DIO 3
XM_EXT_ADC_8 DIO 4
XM_EXT_ADC_9 DIO 5
XM_EXT_ADC_10 DIO 6
XM_EXT_ADC_11 DIO 7
XM_EXT_ADC_12 DIO 8

Once switched, the pin stays in ADC mode until the board is reset — this is intentional safety behavior.

Notes on External IMU Usage

Activating an external IMU (e.g., XSENS MTi) via XM_AttachXsensMTi630() reassigns some pins to UART.

For activation details, see External IO API — External IMU Control

Common Issues

Situation Solution
ADC always reads 0 or 3.3 V only Missing pull-down resistor or short circuit. Check the FSR voltage-divider circuit (FSR — DIO pin — 10 kΩ — GND)
Cannot switch back to DIO after switching Reset the board or cycle power (intentional safety behavior)
DigitalWrite has no effect The pin has been switched to ADC mode. ADC pins must be accessed through the ADC API only
High ADC noise Use short jumper wires and a common GND; add an external RC filter if needed