Tasmota is an open-source firmware for smart home devices that allows for the control and management of connected devices through a web interface. It includes a feature called "Drivers" which allows users to extend its functionalityby adding custom code in the form of a driver.
When the PM1003Message class is added as a driver to Tasmota using the tasmota.add_driver() method, Tasmota will make the methods in the PM1003Message class available to the main Tasmota firmware. This allows the Tasmota firmware to use the methods in the PM1003Message class to communicate with the PM1003 sensor and process the response messages received. When loaded, a driver shall keep periodically running, which for this driver keeps pooling the sensor for data by sending magic packets and listening to the serial answers.
To make it run, add the following commands to the file autoexec.be in the ESP32 flashed with Tasmota:
import PM1003Driver as pm_sensor
tasmota.add_driver(pm_sensor)In order to stop the driver you can use the command:
tasmota.remove_driver(pm_sensor)The PM1003Message class is used to parse and validate messages received from a PM1003 sensor over a serial connection. The Tasmota firmware on the device running this code likely uses the PM1003Message class to send request messages to the sensor and process the responses received.
The static variables at the beginning of the class define the patterns for the request and response messages. For example, the request_pm static variable contains the bytes for a message that requests the PM2.5 measurement from the sensor.
The Tasmota firmware can use the parse_pm() method to process a response message from the sensor and extract the PM2.5 measurement. It can also use the get_color() method to determine the color-coded level of the measurement based on the rules specified in the code.
The other methods in the PM1003Message class (e.g. validate(), parse_serial_number(), parse_firmware_version()) can be used to process other types of response messages from the sensor and extract the relevant data.
The Tasmota firmware can use the isvalid() method to verify that a response message from the sensor is valid before attempting to parse it. If the message is invalid, the Tasmota firmware can use the inspect() method to determine the reason for the failure and take appropriate action (e.g. requesting the measurement again, logging an error).
This is how the how the PM1003Message class is used to communicate with the PM1003 sensor:
- The Tasmota firmware sends a request message to the PM1003 sensor over a serial connection. The request message can be one of the following types:
- PM2.5 measurement
- Serial number
- Firmware version
- The Tasmota firmware uses the static variables at the beginning of the PM1003Message class to create the request message. For example, to request the PM2.5 measurement, the Tasmota firmware can use the request_pm static variable like this:
send_data(PM1003Message.request_pm)where send_data() is a function that sends the bytes over the serial connection.
-
The PM1003 sensor receives the request message and processes it. If the request is valid, the sensor sends a response message back to the Tasmota firmware containing the requested data. The response message has a specific format defined by the sensor's protocol.
-
The Tasmota firmware receives the response message from the sensor and passes it to the PM1003Message class for parsing and validation. It then can use "isvalid()" method to check if the response message is valid. If the message is valid, the Tasmota firmware can use one of the parsing methods (e.g. "parse_pm()", "parse_serial_number()", "parse_firmware_version()") to extract the relevant data from the message. If the message is invalid, the Tasmota firmware can use the "inspect()" method to determine the reason for the failure and take appropriate action.
- The "get_color()" method can be used to determine the color-coded level of the PM2.5 measurement based on the rules specified in the code.