Pimoroni BME680 Environment sensor

So, having a display is all well and good, but now you need something to display.

The Pimoroni BME680 breakout board has a Bosch BME680 temperature, pressure, humidity and air quality sensor.

The following code assumes you have the BME680 and the SH1106 OLED display on the default I2C addresses.

import os
import time
import datetime
import sys

from PIL import Image
from PIL import ImageFont
from PIL import ImageDraw

import bme680
from luma.core.interface.serial import i2c
from luma.oled.device import sh1106
from luma.core.render import canvas

TEMPERATURE_UPDATE_INTERVAL = 0.1  # in seconds

# Temperature offset 
TEMP_OFFSET = 0.0

print("Temperature/pressure monitor - OLED")
print("Initialising")

# Instantiate object for SH1106 OLED display
oled = sh1106(i2c(port=1, address=0x3C), rotate=2, height=128, width=128)

# Instantiate object to read  BME680 sensor
sensor = bme680.BME680()

# Set up the sensors
sensor.set_humidity_oversample(bme680.OS_2X)
sensor.set_pressure_oversample(bme680.OS_4X)
sensor.set_temperature_oversample(bme680.OS_8X)
sensor.set_filter(bme680.FILTER_SIZE_3)
sensor.set_temp_offset(TEMP_OFFSET)

# Build the fonts
rr_path = os.path.abspath(os.path.join(os.path.dirname(__file__), 'fonts',
                                       'Roboto-Regular.ttf'))
rb_path = os.path.abspath(os.path.join(os.path.dirname(__file__), 'fonts',
                                       'Roboto-Black.ttf'))
rr_24 = ImageFont.truetype(rr_path, 24)
rb_20 = ImageFont.truetype(rb_path, 20)
rr_15 = ImageFont.truetype(rr_path, 15)
rr_40 = ImageFont.truetype(rr_path, 40)

# Get sensor data first so that device settings take effect
sensor.get_sensor_data()
# Get the initial date/time and max/min temperature
low_temp = sensor.data.temperature
high_temp = sensor.data.temperature
curr_date = datetime.date.today().day

last_checked = time.time()

# Main loop
while True:
    if sensor.get_sensor_data():
        temp = sensor.data.temperature
        press = sensor.data.pressure
        humidity =sensor.data.humidity
        if datetime.datetime.today().day == curr_date:
            if temp < low_temp:
                low_temp = temp
            elif temp > high_temp:
                high_temp = temp
        else:
            curr_date = datetime.datetime.today().day
            low_temp = temp
            high_temp = temp

        # Write data to canvas
        with canvas(oled) as draw:
            draw.text((65, 55), u"{0:4.0f}".format(press), fill="white", font=rb_20)
            draw.text((1, 55), u"{0:2.1f}%".format(humidity), fill="white", font=rb_20)
            draw.text((1, 1), u"{0:2.0f}°".format(temp), fill="white", font=rr_40)

            draw.text((65, 4), u"max: {0:2.0f}°".format(high_temp), fill="white", font=rr_15)
            draw.text((65, 30), u"min: {0:2.0f}°".format(low_temp), fill="white", font=rr_15)

            if int(time.time()) % 2 == 0:
                draw.text((14, 78), datetime.datetime.now().strftime("%H:%M"),
                          fill="white", font=rr_40)
            else:
                draw.text((14, 78), datetime.datetime.now().strftime("%H %M"),
                          fill="white", font=rr_40)

    time.sleep(TEMPERATURE_UPDATE_INTERVAL)

And this is the result.

There is a potential issue with the temperature. The temperature sensor is directly above the Raspberry Pi Zero, and more importantly close to being above the processor. This does mean that the heat from the processor may well be affecting the temperature being sensed and hence displayed.

Dealing with that is for the next instalment.

Pimoroni 1.12" OLED breakout

A long time ago I bought a Pimoroni Breakout Garden and a selection of breakouts.

I had intended to write some very simple test code  and put it on the blog, unfortunately I then managed to break the SD card with the code on. Must remember to back up regularly...

The Breakout Garden equipped Pi Zero then languished at the back of the cupboard while other, shinier things caught my attention.

And then I wanted to know what the temperature was. I do have a number of pieces of technology that would do that (Arduino, Micro:Bit, Raspberry Pi), but decided that the Breakout Garden would be a good starting point.

But first I wanted to check out the operation of the OLED display.

1.12" OLED breakout

Pimoroni provide a good set of example code, including a complete weather station, but I wanted to build my own using the supplied modules.

First off a simple piece of Python to display a message on the screen.

# Simple test of a Pimoroni SH1106 Breakout board attached to a Breakout Garden HAT

# Required modules
from luma.core.interface.serial import i2c, spi
from luma.core.render import canvas
from luma.oled.device import ssd1306, ssd1309, ssd1325, ssd1331, sh1106

# Instantiate a luma SH1106 object
oled = sh1106(i2c(port=1, address=0x3C), rotate=2, height=128, width=128)

# Create a suitable canvas to draw on
with canvas(oled) as draw:
    draw.rectangle(oled.bounding_box, outline="white", fill="black")
    draw.text((30, 40), "Hello SH1106!", fill="white")

print("There should be something on the display now")

References

https://luma-oled.readthedocs.io/en/latest/python-usage.html

https://luma-oled.readthedocs.io/en/latest/

PIMORONI Breakout Garden

The Pimoroni Breakout Garden HAT is a clever way of allowing the development of sophisticated sensor and display systems without having to do lots of soldering.

 As a HAT, it is fitted with a female 2x20 pin socket so it can be attached to any Raspberry Pi with 2x20 way expansion bus (Raspberry Pi Plus versions to date). Raspberry Pi Zero boards require the headers to be added (the Raspberry Pi Zero WH is supplied with the header already soldered/

This is going to be used with a Raspberry Pi Zero WH fitted into a Pibow Zero W case. To improve stability, a Pibow Breadboard Base was added to the bottom of the stack of laser cut acrylic slices that make up the case. The supplied bolts are long enough to take the additional slice.

Assembly was reasonably straightforward, I did need to ease a couple of the corners with a curved needle file to make the Zero board fit correctly.

To use a Zero with a keyboard and display, you do need to have an On The Go cable for the micro USB (top) and a Micro to HDMI adapter (bottom). I got mine as part of the Pimoroni OctoCam package.

The key feature of the Breakout Gatden HAT is the six large sockets on the top.

These are designed to take the special format breakout board from Pimoroni.

The first breakout board is the BME680 Air Quality Sensor.

Back

The front shows the five connectors. The power and ground connections are diode protected, so if you do plug them in the wrong way round, nothing bad (or indeed nothing at all) happens.

The breakout has temperature, pressure, humidity and air quality sensors built in.

The LSM303D is a combined accelerometer and magnetometer

It can provide X, Y, Z values for acceleration and magnetic field strength (making it suitable for use as a digital compass).

The third sensor is the BMP280 temperature, pressure and altitude sensor.

The last breakout board I have is the 1.12" 128x128 pixel OLED display board.

Next, putting them all to work.