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107 lines
3.7 KiB
107 lines
3.7 KiB
# Detect proximity - Virtual IoT Hardware
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In this part of the lesson, you will add a proximity sensor to your virtual IoT device, and read distance from it.
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## Hardware
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The virtual IoT device will use a simulated distance sensor.
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In a physical IoT device you would use a sensor with a laser ranging module to detect distance.
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### Add the distance sensor to CounterFit
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To use a virtual distance sensor, you need to add one to the CounterFit app
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#### Task - add the distance sensor to CounterFit
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Add the distance sensor to the CounterFit app.
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1. Open the `fruit-quality-detector` code in VS Code, and make sure the virtual environment is activated.
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1. Install an additional Pip package to install a CounterFit shim that can talk to distance sensors by simulating the [rpi-vl53l0x Pip package](https://pypi.org/project/rpi-vl53l0x/), a Python package that interacts with [a VL53L0X time-of-flight distance sensor](https://wiki.seeedstudio.com/Grove-Time_of_Flight_Distance_Sensor-VL53L0X/). Make sure you are installing this from a terminal with the virtual environment activated.
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```sh
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pip install counterfit-shims-rpi-vl53l0x
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```
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1. Make sure the CounterFit web app is running
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1. Create a distance sensor:
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1. In the *Create sensor* box in the *Sensors* pane, drop down the *Sensor type* box and select *Distance*.
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1. Leave the *Units* as `Millimeter`
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1. This sensor is an I<sup>2</sup>C sensor, so set the address to `0x29`. If you used a physical VL53L0X sensor it would be hardcoded to this address.
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1. Select the **Add** button to create the distance sensor
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The distance sensor will be created and appear in the sensors list.
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## Program the distance sensor
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The virtual IoT device can now be programmed to use the simulated distance sensor.
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### Task - program the time of flight sensor
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1. Create a new file in the `fruit-quality-detector` project called `distance-sensor.py`.
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> 💁 An easy way to simulate multiple IoT devices is to do each in a different Python file, then run them at the same time.
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1. Start a connection to CounterFit with the following code:
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```python
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from counterfit_connection import CounterFitConnection
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CounterFitConnection.init('127.0.0.1', 5000)
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```
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1. Add the following code below this:
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```python
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import time
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from counterfit_shims_rpi_vl53l0x.vl53l0x import VL53L0X
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```
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This imports the sensor library shim for the VL53L0X time of flight sensor.
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1. Below this, add the following code to access the sensor:
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```python
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distance_sensor = VL53L0X()
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distance_sensor.begin()
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```
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This code declares a distance sensor, then starts the sensor.
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1. Finally, add an infinite loop to read distances:
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```python
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while True:
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distance_sensor.wait_ready()
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print(f'Distance = {distance_sensor.get_distance()} mm')
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time.sleep(1)
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```
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This code waits for a value to be ready to read from the sensor, then prints it to the console.
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1. Run this code.
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> 💁 Don't forget this file is called `distance-sensor.py`! Make sure to run this via Python, not `app.py`.
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1. You will see distance measurements appear in the console. Change the value in CounterFit to see this value change, or use random values.
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```output
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(.venv) ➜ fruit-quality-detector python distance-sensor.py
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Distance = 37 mm
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Distance = 42 mm
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Distance = 29 mm
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```
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> 💁 You can find this code in the [code-proximity/virtual-iot-device](code-proximity/virtual-iot-device) folder.
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😀 Your proximity sensor program was a success! |