M308 add a new sensor

dc42

@moth4017 can you use the BME280 instead? We're planning to support that one in RRF 3.5. Unlike the AHT25 it supports SPI (not just I2c) which makes it easier to integrate into RRF.

gloomyandy

@jay_s_uk My guess is that it is this: http://www.aosong.com/en/products-61.html

@moth4017 Any reason to use the AHT25 rather than the DHT sensor that is already supported?
https://docs.duet3d.com/en/User_manual/Connecting_hardware/Temperature_connecting_DHT

moth4017

@jay_s_uk

http://www.aosong.com/en/products-61.html

Ive been using it with a esp32 and th btncmd pulgin with the duet3 Mini 5 , but would be nice to attach it direct .

The BME280 looks like it was designed to operate up to 65C although it is rated to 85C , this should be ok for our application.

moth4017

@gloomyandy
The DHT does not seem to be very accurate at low humidity values

moth4017

@dc42 , BME 280 ordered to try when the v3.5 is out..

moth4017

@dc42 is there any info on how to connect and setup the BME280?

Exerqtor

@moth4017 said in M308 add a new sensor:

@dc42 is there any info on how to connect and setup the BME280?

It's been added to M308 for RRF3.5 and later at least.

Reguarding how to connect it i would guess you do it just like you would with a DHT sensor.

moth4017

@Exerqtor Hi the NME280 is an SPI device , so im guessing there is more to set up and im not sure which chip select pin is used.

dc42

@moth4017 the BME280 can be connected to the SPI daughter board connector. You can use any one of the CS pins on that connector.

moth4017

@dc42 Thanks, do you have to define the CS pin like this?

if i was to use spi2 CS2

M308 S1 P"spi2.cs2" Y"BME280" A"BME280"

dc42

@moth4017 yes it's the same as how you would define the CS pin for a PT100 or thermocouple board.

Accessing the 2 additional sensors in the BME280 is similar to how you access humidity on a DHT22. Here's how I configured a BME280 on a Duet 3 Mini:

m308 s11 y"bme280" p"spi.cs1" a"Ambient temp"
m308 s12 y"bmepressure" p"s11.1" a"Pressure[hPa]"
m308 s13 y"bmehumidity" p"s11.2" a"Humidity[%]"

Exerqtor

@dc42

I assume we don't connect/use the clock pin on the BME280 ?

dc42

@Exerqtor you need to connect the SDI, SDO and SCK pins of the BME280 to MOSI, MISO and SCLK respectively. And of course also connect CS, 3.3V power and ground.

moth4017

BME connected and working , i have used spi.cs2

M308 s11 y"bme280" p"spi.cs2" A"Ambient temp"
M308 s12 y"bmepressure" p"s11.1" A"Pressure[hPa]"
M308 s13 y"bmehumidity" p"s11.2" A"Humidity[%]"

A bit of info as the Pin out description on the BME not the same as Duet board

Duet Temp Daughter Board to BME 280
pin 1 .................................................. CSB
pin2 ................................................... GND
pin3
pin4.................................................... SCL
pin5 ................................................... SDA
pin6.................................................... SDO
pin7
pin8................................................... VCC
pin9
pin10

Tinchus

Hello all. Just to confirm: using the BME280 is not possible yet on version 3.4 versions of firmware?

jay_s_uk

@Tinchus correct. its part of 3.5

Tinchus

@jay_s_uk Hello Thanks for the answer, then I should update to 3.5 beta to test this.

Docs talk about connecting the BME280 to the temperature daughter board. I have a thermocouple doughter board, it will work?

jay_s_uk

@Tinchus depending on which board you have. best off opening a new thread