The SN-GCJA5 particulate matter sensor from Panasonic Industries uses a laser diode instead of a light emitting diode (LED) to more reliably detect the quantities of PM2.5, PM10 & PM1 sized particles within the enclosure’s detection zone. A micro-fan is used to generate air flow and a microprocessor is then used to analyse the particulate matter counts based on a predefined algorithm to calculate particulate matter densities and this data is then transmitted via UART and I2C communication protocols.

The features and benefits of this sensor, as listed on the Panasonic North American website’s product page are as follows:

• Panasonic’s On-Board Micro-Processor makes it unnecessary to design your own measurement algorithms - all you do is read the output from UART or I2C bus
• The inclusion of a Micro-Fan is more efficient than using a heating element to draw air into the sensor
• Panasonic’s Particulate Matter Sensor provides a more accurate light scattering performance using a laser diode than Light Emitting Diodes (LEDs)
• Panasonic’s Proprietary Algorithm controls the fan and the Laser Diode Efficiency for a prolonged product life

In addition to the above, the main Panasonic website also lists the auto calibration function as a feature.

I was not able to validate any of these claims other than the first one. It really was much easier to obtain measurement data than the other two sensors I tested as a comparison (see below).

What's not listed was that the sensor also provides a status function to indicate to the user if a fault has been detected. I thought this was a very useful feature.

The sensor does not come with demo software, hence the score given for "Demo Software was of good quality" category is NA (Not Applicable).

For this roadtest I reviewed how quickly it took me to get up to speed and develop an application using the documentation provided.

As I don’t have any calibration instruments to validate readings I also made comparative observations based on two other dust sensors I’ve used in the past, namely the Sharp GP2Y1026AU0F and the G5W-LD0101 from Omron.

Then by way of demonstration, I created three blogs explaining what could be done. The first two blogs were getting started guides demonstrating how easy it was to get started using UART and I2C with a Raspberry Pi Pico board and the Arduino IDE.

https://community.element14.com/products/roadtest/b/blog/posts/getting-started-with-the-panasonic-sn-gcja5-laser-type-particulate-matter-pm-sensor-using-uart-ttl

https://community.element14.com/products/roadtest/b/blog/posts/using-i2c-communication-with-the-panasonic-sn-gcja5-laser-type-particulate-matter-pm-sensor

The third blog described how to build a BLE application using both the SN-GCJA5 particulate matter sensor and the B5W-LD01 from Omron.

https://community.element14.com/technologies/code_exchange/b/blog/posts/creating-a-small-bluetooth-low-energy-ble-particulate-matter-pm-air-quality-sensor-node-network-using-mbed-os-6-15-and-mit-app-inventor-for-the-hub

A further demonstration using the Sharp GP2Y1026AU0F sensor with the SN-GCJA5 sensor will be provided in another blog for Arduino (I used the Arduino MKR1000 as the MCU).

The SN-GCJA5 square enclosure is a mere 37mm x 37mm and is only 12mm thick, making it the smallest PM sensor enclosure I’ve ever come across.

However, this enclosure appears to be missing mounting holes. It was not immediately apparent as to how one fixes the enclosure in place. The above diagram indicates 3 screw holes for fixing but two of those already have screws on the underside keeping the two parts of the enclosure together. The sensor documentation instructs the user not to remove those two screws. I did not attempt to use the 3rd screw hole in case it damaged the sensor.

By way of comparison, the larger Omron B5W-LD01 sensor does include mounting holes while the Sharp GP2Y1026 sensor did not, although it did have a ledge to hold it in place.

The managed air flow through the SN-GCJA5 sensor is via a separated inlet and outlet port on the underside of the sensor when mounted vertically (see above diagram for location of each). The Omron B5W-LD01 sensor also has an inlet port on the underside of the sensor but the outlet is on the side of the sensor. The Sharp GP2Y1026 has a circular hole through the middle of the sensor.

The connector used on the SN-GCJA5 sensor is a 5-pin JST (SM05B-GHS-TB) Wire-to-Board type connector with a 1.25mm pitch. As we all discovered, getting hold of a cable harness with this connector is hard to find at the moment as frequently distributors are temporarily out of stock.

This sensor is not the only one with a unique connector. The Sharp GP2Y sensor uses a 6-pin, 1.5mm pitch JCTC connector (11501W90-6P-S-HF) and the Omron B5W-LD01 sensor uses a 5 pin, 2mm pitch TE connector (AMP 292164-5).

The difference though is that with these two other sensors, it is easy to hack on your connector if you could not get hold of a suitable connector.

The technical details of the sensor hardware is provided within the Panasonic SN-GCJA5 spec sheet: JA5-SSP-E20_Product-Specifications_e.pdf

As a summary here is a comparison of the key parameters against other sensors.

The Data Transfer Communication Protocol

Concluding Remarks