Accelerometer Usage

Usage Guide

C8P Motherboard Accelerometer Usage Limitations

Due to the hardware design of the C8P motherboard, it cannot directly connect to and drive standalone SPI/I²C accelerometer modules (such as ADXL345).

If you need to use an accelerometer on a device based on the C8P motherboard, please choose one of the following options:

Option	Recommended Product	Connection/Description
1. USB Accelerometer	FLY-USB-LIS2DW	A LIS2DW accelerometer with a USB interface, simply plug it into the host computer's USB port for immediate use, no connection to the motherboard required.
2. Accelerometer Integrated in Tool Board	Expansion tool boards integrated with LIS2DW or ADXL345	Communicates with the motherboard via CAN or other interfaces, the accelerometer is identified and accessed as part of the tool board.

Important Notice: Never attempt to directly connect modules like ADXL345 to the pins of the C8P motherboard. To ensure compatibility and proper functionality, we recommend using the FLY-USB-LIS2DW USB accelerometer specifically designed for external acceleration measurement.

Dependency Package Installation

warning

Notes

• If your device is already running the FlyOS-FAST system, the required dependencies are pre-installed, and you can skip this step.
• If using a non-FLY host computer, please be sure to complete the installation steps below.
• It is recommended to connect using SSH tools such as MobaXterm or PuTTY.

Installation Steps

1. Execute the following commands in sequence to install the dependency packages.
2. Installation time depends on CPU performance and network conditions; usually takes 10–20 minutes, please wait patiently until installation completes.
3. If the device has insufficient memory (RAM), the installation may fail.

Install system dependencies:

sudo apt install python3-numpy python3-matplotlib libatlas-base-dev

Install Klipper virtual environment dependencies:

~/klippy-env/bin/pip install matplotlib numpy

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Accelerometer Testing

Prerequisites

• The printer has performed the homing operation.
• Ensure the accelerometer is properly enabled in the Klipper configuration file.

Test Commands

Enter the following command in the Klipper console:

ACCELEROMETER_QUERY

If multiple accelerometers are connected, you can specify a chip for testing:

ACCELEROMETER_QUERY CHIP=<ADXL chip name>

Replace <ADXL chip name> with the actual accelerometer identifier (e.g., adxl345).

Troubleshooting

1. First execution fails: Some Klipper versions may experience command recognition delays. If the first execution returns no data, please execute the same command again.
2. Command not recognized: If the command is still unrecognized after multiple attempts, it may be due to an outdated Klipper version. We recommend:
   • Updating Klipper to the latest version
   • Or re-flashing the latest system version (e.g., latest FlyOS-FAST)

Result Interpretation

• Normal output: If a continuous stream of data is returned (as shown in the image below), the accelerometer is working normally and resonance compensation measurement can proceed.
• Error output: If timeout, no data, or communication errors are reported, please check in order:
  1. Whether the accelerometer wiring is secure
  2. Whether the sensor configuration and SPI in the configuration file are correct
  3. Whether the power supply is stable

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• Note: Some older versions of Klipper require executing ACCELEROMETER_QUERY twice before obtaining accelerometer values

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Accelerometer Calibration

Calibration Steps

1. Ensure the printer has been homed.
2. Enter the following command in the console to start automatic calibration for the X and Y axes:

   SHAPER_CALIBRATE

3. After calibration completes, save the configuration:

   SAVE_CONFIG

Single Axis Calibration

If you need to calibrate only a single axis, use:

SHAPER_CALIBRATE AXIS=X

Or replace X with Y.

caution

Safety Tip

• The printer may generate intense vibrations during calibration. If vibrations become too strong, immediately press the emergency stop button or send the M112 command to stop urgently.

Adjusting Vibration Intensity

If the vibration during testing is too intense, you can reduce the accel_per_hz parameter value (default is 75):

[resonance_tester]
accel_per_hz: 50

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Note: The steps above apply to most Klipper-based 3D printer resonance compensation configurations. Adjust according to your actual hardware and system environment.