i2c sensors on klipper

Prerequisites

• A working instance of Klipper, Moonraker and / or Mainsail/Fluidd
• Access to the Raspberry PI/CB1/Orange pi terminal.
• If using the GPIO pins [set as a secondary mcu] (https://www.klipper3d.org/RPi_microcontroller.html)
• If using something else to run kipper i.e. a virtual machine we are using a raspberry pico.

IMPORTANT

This guide is aimed towards i2c temp sensors, but should work for most i2c devices such as accelerometers.

Overview

Why i2c sensors instead of a thermistor?

Normal thermistors are perfectly fine and easy to setup but most sensors allow you to track temperatures, humidity and in some cases VOC's.

Example

Connection.

All the i2c sensors use 4 cables, VCC, GND, SDA, SCL. if your sensor has more ignore them.

IMPORTANT

Some sensors use 3.3V or 5V. PLEASE double check voltages, some boards like de CB1 have an output of 1.8V instead of 3.3v in some pins (dunno why).

If using a raspberry pi

Easiest to setup.

VCC -> 3.3V (or 5v)

GND -> any gnd pin

SDA -> PIN3

SCL -> PIN5

If using a CB1

VCC -> 3.3V or 5V (Remember sometimes this board uses 1.8v instead of 3.3v)

GND -> Any ground pin

SDA -> pin 10

SDL -> pin 8

If using a pico

Any sda and scl pin should work. I used pin 1 and 2.

Config

RASPBERRY PI

1. Enable i2c.

sudo raspi-config

Option 3) interface options -> I4 I2C -> Enable

2. Get the address (my sensor has an address of x77) While I was writing this I found out Wiringpi has been deprecated, as I read the story I feel bad for the author, so here's the story.

https://web.archive.org/web/20220405225008/http://wiringpi.com/wiringpi-deprecated/

The original command was:

i2cdetect -y 1

if using an orange pi check https://github.com/orangepi-xunlong/wiringOP

CB1

1. CB1 has no interface like the pi so go to: Boot/BoardEnv.txt and uncomment: overlays=light or if using more than one, separate them with a space i.e. overlays=light tft35_spi

I used

sudo nano /boot/BoardEnv.txt

ctrl+x and hit yes

3. Come back after everything is set, and type

cat /sys/kernel/debug/gpio

you should see klipper is using the pins

Pico

1. Flash the pico following this guie https://www.klipper3d.org/Measuring_Resonances.html?h=pico#flash-the-pico-firmware

2. get the serial

Klipper

go to the config in mainsail/fluidd and make a new file like bme.cfg and copy

RPi

[mcu rpi] # Not needed if used before
serial: /tmp/klipper_host_mcu 

[temperature_sensor chamber]
sensor_type: BME280
i2c_address: 119 # RIP WIRINGPI
#   Default is 118 (0x76). Some BME280 sensors have an address of 119
#   (0x77).
i2c_mcu: rpi
i2c_bus: i2c.1
#i2c_speed:
#   See the "common I2C settings" section for a description of the
#   above parameters.

[gcode_macro QUERY_CHAMBER]
gcode:
    {% set sensor = printer["bme280 chamber"] %}
    {action_respond_info(
        "Temperature: %.2f C\n"
        "Pressure: %.2f hPa\n"
        "Humidity: %.2f%%\n"
        "Gas Level: %.2f VOC" % (
            sensor.temperature,
            sensor.pressure,
            sensor.humidity,
            sensor.gas_level))}

CB1

[mcu host]
serial: /tmp/klipper_host_mcu

[temperature_sensor chamber]
sensor_type: BME280
i2c_address: 119
#   Default is 118 (0x76). Some BME280 sensors have an address of 119
#   (0x77).
i2c_mcu: host
i2c_software_scl_pin: gpio224
i2c_software_sda_pin: gpio225
#i2c_bus: i2c.1
#i2c_speed:
#   See the "common I2C settings" section for a description of the
#   above parameters.

[gcode_macro QUERY_CHAMBER]
gcode:
    {% set sensor = printer["bme280 chamber"] %}
    {action_respond_info(
        "Temperature: %.2f C\n"
        "Pressure: %.2f hPa\n"
        "Humidity: %.2f%%\n"
        "Gas Level: %.2f VOC" % (
            sensor.temperature,
            sensor.pressure,
            sensor.humidity,
            sensor.gas_level))}

pico

[mcu rp2040]
serial: /dev/serial/by-id/<YourDevice>
[temperature_sensor chamber]
sensor_type: BME280
i2c_address: 119
#   Default is 118 (0x76). Some BME280 sensors have an address of 119
#   (0x77).
i2c_mcu: rp2040

[gcode_macro QUERY_CHAMBER]
gcode:
    {% set sensor = printer["bme280 chamber"] %}
    {action_respond_info(
        "Temperature: %.2f C\n"
        "Pressure: %.2f hPa\n"
        "Humidity: %.2f%%\n"
        "Gas Level: %.2f VOC" % (
            sensor.temperature,
            sensor.pressure,
            sensor.humidity,
            sensor.gas_level))}

Add [include bme.cfg] to your printer.cfg and you should be able to see your sensor in the dashboard n.n