pmcu-firmware hosts the code that runs on the MSP430F5529, that makes the PMCU actually work.

Components:

Device	Description
MSP430F5529	The MCU used
GY-GPS6MW2	For GPS purposes
SIM800L	For the communication over the GSM network
DHT22	For temperature and humidity measures
SPS30	For PM measures

Firmware logic:

Setup phase:

• SPS30 is set to measurement mode.
• Waits 5 minutes in order to let modules setup (like SPS30).

Looping phase:

• Inits transferring buffer.
• Puts GPS data in it.
• Puts DHT22 temperature and humidity.
• Puts SPS30 data.
• Sends data through 2G network.

Those operations are repeated every 30 seconds.

SPS30 fan cleaning phase:

• Starts fan cleaning.
• Waits 15 seconds.

It's done every hour. When a fan cleaning occurs no measurement will be done (a looping phase frame is dropped).

Packet structure:

Size	Type	Name	Unit
2 bytes	String	Phone Number
? < 60 bytes	String	NMEA GSA sentence
? < 60 bytes	String	NMEA GGA sentence
2 bytes	Unsigned int	Temperature	°C x10
2 bytes	Unsigned int	Humidity	RF x10
4 bytes	Float	Mass concentration PM1.0	ug/m^3
4 bytes	Float	Mass concentration PM2.5	ug/m^3
4 bytes	Float	Mass concentration PM4.0	ug/m^3
4 bytes	Float	Mass concentration PM10	ug/m^3
4 bytes	Float	Number concentration PM0.5	#/cm^3
4 bytes	Float	Number concentration PM1.0	#/cm^3
4 bytes	Float	Number concentration PM2.5	#/cm^3
4 bytes	Float	Number concentration PM4.0	#/cm^3
4 bytes	Float	Number concentration PM10	#/cm^3
4 bytes	Float	Typical particle size	um

Networking

The packet is sent over the 2G network, via UDP, to an MQTT broker.