How to connect an accelerometer to an SKR-RRF-E3

Overview

The only type of accelerometers that are supported are LIS3DH and LIS3DSH.

Wiring

It is recommended to use a USB3 cable for the wiring between the board and the accelerometer.

USB3 Cross-Section
USB3 Cross-Section

The colours used in the table below match the colour coding above.

One possible method of connecting the accelerometer to the SKR-RRF-E3 is described in the table below. The image can be used to aid in identification.

These connections are on the EXP1 header on the board.

Accelerometer Image Wire Colour Accelerometer Pin Name Accelerometer Pin Type SKR-RRF-E3 Pin
Red VIN +5v Input +5v
Black GND Ground GND
Purple SCL SPI SCK PB_1
Blue SDA SPI MOSI PE_11
Yellow SDO SPI MISO PB_2
Green CS Chip Select PE_10
Orange Int Interupt PE_7
LIS3DH Pinout
LIS3DH Pinout

Mounting the LIS3DH

The accelerometer should be mounted firmly to the tool. For a bed slinger (such as an ender 3), it should also be possible to mount it to the bed to take readings for the Y axis.

Boart.txt Changes

Add the following to board.txt

SPI5.pins = { PB_1, PB_2, PE_11 }
accelerometer.spiChannel = 5

Config.g Changes

Your config.g should be modified as below.

M955 P0 C"PE_10+PE_7" I20

The I (orientation) parameter tells the firmware which of the 24 possible orientations the accelerometer chip is in relative to the printer axes. It is expressed as a 2-digit number.
The first digit specifies which machine direction the Z axis of the accelerometer chip (usually the top face of the chip) faces, as follows: 0 = +X, 1 = +Y, 2 = +Z, 4 = -X, 5 = -Y, 6 = -Z. The second digit expresses which direction the X axis of the accelerometer chip faces, using the same code. The direction of positive X is printed on the circuit board. If the board was mounted in the orientation shown in the above image, with +X of the machine being to the right, Y+ being behind and Z+ being up, the I value would be 54. This document gives information regarding the I value for the new Duet toolboard with accelerometer.
20 is the default orientation if no orientation has been specified.

DWC Plugin

There is an input shaper plugin to capture and analyse the data. It can be found here

Usage

The accelerometer can be activated using M956

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