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Sensor Extended

Table of Contents

Prolog

This time we turn to other sensors and various possibilities to display the measured values or to react to them. Depending on the options and sensors that are available, simply adapt the examples to your needs.

Measure environment decibel (MAX9814 - SSD1306)

In this example, the ambient noise is to be measured and shown on a display (in decibel).

Requirements

  • mandatory 1x Microphone (example MAX9814)
  • mandatory 1x I2C OLED (example 0.96" 128x64)
  • few cables
  • optional a breadboard

Example

max9814.jpg

Pinout table

Here you can see the respective wiring for the circuit.

Device Name Device Pin ESP32 Pin
OLED Display GND GND
OLED Display VCC 3V3
OLED Display SCL 22
OLED Display SDA 21
Microphone GND GND
Microphone Vdd 3V3
Microphone Out 34

Code

# create local script
$ touch ~/Projects/ESP/examples/sensors/max9814.py

Since an OLED display is used here to display the decibel values, other modules and fonts are required in addition to the example script.

Source Code for example max9814.py

Source Code for module ssd1306.py

Source Code for module writer.py

Source Code for font freesans20.py

Check your circuit careful, connect the microcontroller and copy needed files to the microcontroller.

# connect via rshel
(venv) $ rshell -p [SERIAL-PORT]

# copy module file into /pyboard/lib/
/your/current/path> cp lib/ssd1306.py /pyboard/lib/
/your/current/path> cp lib/writer.py /pyboard/lib/
/your/current/path> cp lib/freesans20.py /pyboard/lib/

# copy script as main.py
/your/current/path> cp examples/sensors/max9814.py /pyboard/main.py

# start repl
/your/current/path> repl

Start with keys Control + d or press reset key. To stop the loop press keys Control+ c, to leave the REPL, press keys Control + x.

Obstacle Detection (Laser Sensor - SSD1306)

Everything goes very fast and your vehicles and robots must be able to stop and resume movements very quickly. With the following example you will learn to control these fast movements via obstacle detection. A laser sensor is used for this.

Note: The example uses IRQ multiplexing to respond to interrupts! If you don't understand how IRQs working, please have a look here.

Requirements

  • mandatory 1x Laser Sensor 10929 (Waveshare)
  • mandatory 1x I2C OLED (example 0.96" 128x64)
  • few cables
  • optional a breadboard

Example

laser_sensor.jpg

Pinout table

Here you can see the respective wiring for the circuit.

Device Name Device Pin ESP32 Pin
OLED Display GND GND
OLED Display VCC 3V3
OLED Display SCL 22
OLED Display SDA 21
Laser Sensor GND GND
Laser Sensor VCC 3V3
Laser Sensor DOUT 23

Code

# create local script
$ touch ~/Projects/ESP/examples/sensors/laser_sensor_10929.py

# download images
$ curl -L 'https://raw.githubusercontent.com/Lupin3000/ESP/master/images/src/go.pbm' -o images/src/go.pbm
$ curl -L 'https://raw.githubusercontent.com/Lupin3000/ESP/master/images/src/stop.pbm' -o images/src/stop.pbm

The OLED display is used to display 2 images for obstacle detection (Stop & Go). Therefor 2x *.pbm images and 1x driver module are required in addition to the example script.

Source Code for example laser_sensor_10929.py

Source Code for module ssd1306.py

Check your circuit careful, connect the microcontroller and copy needed files to the microcontroller.

# connect via rshel
(venv) $ rshell -p [SERIAL-PORT]

# copy images into /pyboard/ directory
/your/current/path> cp images/src/go.pbm /pyboard/
/your/current/path> cp images/src/stop.pbm /pyboard/

# copy script as main.py
/your/current/path> cp examples/sensors/laser_sensor_10929.py /pyboard/main.py

# copy module file into /pyboard/lib/
/your/current/path> cp lib/ssd1306.py /pyboard/lib/

# start repl
/your/current/path> repl

Start with keys Control + d or press reset key. To stop the program and to leave the REPL, press keys Control + x.

Light Barrier (ALLNET: B18 - Pushover)

In the next example, a sensor with a light barrier is used. As soon as the light barrier is interrupted, a push notification should be sent to a mobile. An NTP time synchronization is carried out beforehand so that the time of the interruption can be sent.

Requirements

  • mandatory 1x Light Barrier (Allnet)
  • mandatory Pushover Application (Pushover)
  • internet
  • few cables
  • optional a breadboard

Example

light_barrier.jpg

Pinout table

Here you can see the respective wiring for the circuit.

Light Barrier ESP32
+5V 5V5
GND GND
OUT 23

Code

# create local script
$ touch ~/Projects/ESP/examples/sensors/allnet_B18_light_barrier.py

The microcontroller needs to have internet connection! Therefor you need to set the device in station mode via boot.py. You can reuse the example from here.

Source Code for example allnet_B18_light_barrier.py

Source Code for station setup boot.py

Check your circuit careful, connect the microcontroller and copy needed files to the microcontroller.

# connect via rshel
(venv) $ rshell -p [SERIAL-PORT]

# copy script as main.py
/your/current/path> cp examples/sensors/allnet_B18_light_barrier.py /pyboard/main.py

# copy boot.py into /pyboard/
/your/current/path> cp examples/network/boot.py /pyboard/boot.py

# start repl
/your/current/path> repl

Start with keys Control + d or press reset key. To stop the program and to leave the REPL, press keys Control + x.

Environment Sensing (Bosh: BME680 - Web Server)

In this example, the measurement data of the BME680 are displayed in the browser.

Requirements

  • mandatory 1x Bosh Sensortec BME680 (or similar)
  • few cables
  • optional a breadboard

Example

bme680.jpg

Pinout table

Here you can see the respective wiring for the circuit.

BME680 ESP32
GND GND
VCC 3V3
SCL 22
SDA 21

Code

# create local script
$ touch ~/Projects/ESP/examples/sensors/bosch_sensortec_bme680.py

The connection will be via WLAN (access point mode). For html a template is used.

Source Code for example bosch_sensortec_bme680.py

Source Code for template template.htm

Source Code for module bme680.py

Check your circuit careful, connect the microcontroller and copy needed files to the microcontroller.

# connect via rshel
(venv) $ rshell -p [SERIAL-PORT]

# copy script as main.py
/your/current/path> cp examples/sensors/bosch_sensortec_bme680.py /pyboard/main.py

# copy template.htm into /pyboard/
/your/current/path> cp examples/sensors/template.htm /pyboard/

# copy module file into /pyboard/lib/
/your/current/path> cp lib/bme680.py /pyboard/lib/

# start repl
/your/current/path> repl

Start with keys Control + d or press reset key. To stop the program and to leave the REPL, press keys Control + x.

Measure Distance (Pimoroni: VL53L1X - SSD1306)

In this example two I2C devices are used in the bus. With the sensor you can measure distances and show them on the display.

If you don't know the HEX addresses, just use the I2C scanner from one of the previous tutorials.

Requirements

  • mandatory 1x Pimoroni VL53L1X TOF (or similar)
  • mandatory 1x I2C OLED (SSD1306)
  • few cables
  • optional a breadboard

Example

vl53l1x.jpg

Pinout table

Here you can see the respective wiring for the circuit.

VL53L1X SSD1306 ESP32
GND GND GND
VCC VCC 3V3
SCL SCL 22
SDA SDA 21

All connections of the circuit are connected in parallel.

Code

# create local script
$ touch ~/Projects/ESP/examples/sensors/pimoroni_vl53l1x.py

Two driver modules are needed! One for the sensor and a second for the display.

Source Code for example pimoroni_vl53l1x.py

Source Code for module lib/vl53l1x.py

Source Code for module lib/ssd1306.py

Check your circuit careful, connect the microcontroller and copy needed files to the microcontroller.

# connect via rshel
(venv) $ rshell -p [SERIAL-PORT]

# copy script as main.py
/your/current/path> cp examples/sensors/pimoroni_vl53l1x.py /pyboard/main.py

# copy module files into /pyboard/lib/
/your/current/path> cp lib/vl53l1x.py /pyboard/lib/
/your/current/path> cp lib/ssd1306.py /pyboard/lib/

# start repl
/your/current/path> repl

Start with keys Control + d or press reset key. To stop the program press keys Control + c and to leave the REPL, press keys Control + x.

It can happen that there are problems with the rshell connection, simply prepare everything in the terminal and execute the command immediately after the USB connection. If that doesn't work either, interrupt the 3V power supply first.

Temperature via WebBLE (Allnet: B38 Temp. Sensor)

Web Bluetooth (WebBLE) is an exciting advance in Bluetooth Low Energy (BLE) development. With less effort you can create awesome applications for example without any internet connection, LAN/WLAN technologies, server or heavy backend programming. Also, (for IoT somehow important) with less power consumption. Here now a very basic example.

Requirements

  • mandatory 1x temperature sensor (Allnet: B38 Temperature Sensor)
  • mandatory 1x device with Google Chrome Browser (with WebBLE support)
  • few cables
  • optional a breadboard

Example

temperature_sensor.jpg

Pinout table

Here you can see the respective wiring for the circuit.

B38 ESP32
GND GND
+5V V5
SCL 22
SDA 21

Code

# create local script
$ touch ~/Projects/ESP/examples/sensors/allnet_B38_temperature.py

# create local html
$ touch ~/Projects/ESP/examples/sensors/webBLE.htm

One helper module and an HTML page is needed! The HTML page stays at the device where Bluetooth is enabled and Google Chrome browser is installed.

Source Code for example allnet_B38_temperature.py

Source Code for helper module lib/ble_advertising.py

Source Code for local webBLE.htm

Check your circuit careful, connect the microcontroller and copy needed files to the microcontroller.

# connect via rshel
(venv) $ rshell -p [SERIAL-PORT]

# copy script as main.py
/your/current/path> cp examples/sensors/allnet_B38_temperature.py /pyboard/main.py

# copy module file into /pyboard/lib/
/your/current/path> cp lib/ble_advertising.py /pyboard/lib/

# start repl
/your/current/path> repl

Start with keys Control + d or press reset key. To stop the program press keys Control + c and to leave the REPL, press keys Control + x.

Enable Bluetooth on the device and open the HTML webBLE.htm inside Google Chrome. Press Connect to device button. Select the ESP32 and wait for few seconds.

Helpful Chrome URLs

  • chrome://bluetooth-internals/#adapter to connect without HTML webBLE.htm example
  • chrome://flags to enable "Experimental Web Platform features"

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