Klipper – Input Shaper w/ Arduino Nano

Want to setup Klipper’s input shaper, but don’t have a Raspberry Pi Pico on hand for a separate Klipper MCU? This article will step through using an Arduino Nano instead. A separate Klipper MCU in this context would allow you to run input shaper on multiple 3D printers by USB without requiring a dedicated ADXL345 sensor on each printer and reducing costs.

Wiring

Solder these pins together.

ADXL345	Arduino Nano
3V3/VCC	3.3V/VCC
GND	GND
CS	D10
SDO	D12
SDA	D11
SCL	D13

Flashing

Connect the Arduino Nano to the Klipper Host, in our case a Raspberry Pi 4. In order for us to flash the Arduino Nano from our Raspberry Pi 4. At this time of writing, there is a bug in avrdude used to flash and we will need to add a previous APT repo.

1. sudo nano /etc/apt/sources.list
2. Add deb http://raspbian.raspberrypi.org/raspbian/ buster main contrib non-free rpi
3. Save and quit (:wq)
4. sudo nano /etc/apt/preferences.d/avr-buster
5. Type below and save file
   Package: avr-libc avrdud binutils-avr gcc-avr
Pin: release n=buster
Pin-Priority: 1001
6. Save and quit (:wq)
7. sudo apt update
sudo apt install avr-libc avrdude binutils-avr gcc-avr
8. cd ~/klipper
9. make menuconfig
10. Change Micro-controller Architecture to Atmega AVR and Processor model to atmega328p
11. Press q and y
12. make clean
make
13. avrdude -patmega328p -c arduino  -b 57600 -P /dev/ttyUSB1 -v  -D -Uflash:w:out/klipper.elf.hex:i
    Note: /dev/ttyUSB1 may be different on your system and per printer primary MCU. Change any reference to match further ahead.
14. Once this is completed, nano will be ready to be used as a Second Klipper MCU

Update 8/31/2023: For those whom wish to copy and paste into a terminal:

Steps 1-7 – Revert to older avrdude. Note: we didn’t test the newer version and may be fixed.

sudo sed -i '$ a\deb http://raspbian.raspberrypi.org/raspbian/ buster main contrib non-free rpi' /etc/apt/sources.list

echo -e "Package: avr-libc avrdude binutils-avr gcc-avr\nPin: release n=buster\nPin-Priority: 1001" | sudo tee /etc/apt/preferences.d/avr-buster > /dev/null

sudo apt update

sudo apt install avr-libc avrdude binutils-avr gcc-avr

Steps 8-13

cd ~/klipper
make menuconfig
make clean
make
avrdude -patmega328p -c arduino  -b 57600 -P /dev/ttyUSB1 -v  -D -Uflash:w:out/klipper.elf.hex:i

Klipper Config

1. Add a config file called adxl.cfg under the Klipper config section for each printer.
2. Add the following lines:

[mcu arduino_nano_adxl]
serial: /dev/ttyUSB1

[adxl345]
cs_pin: arduino_nano_adxl:PB2

[resonance_tester]
accel_chip: adxl345
probe_points:
100,100,30

3. Press save & close
4. Add [include adxl.cfg] to printer.cfg
   Note: if it is not connected to the printer add a # in front of it to disable
5. Press save & restart