Just a few days go another PM2.5 and PM10 particle sensor has landed on my desk. This time is an SDS011, a sensor manufactured by Nova Fitness, a spin-off from the University of Jinan (in Shandong). It’s quite a popular sensor, being used in many citizen science projects, of which I mention the global air quality map maintained by luftdaten.info. I bought it with the intent to use it to make a luftdaten.info monitoring station (and blog about it, of course). But first I will play with it for a few days, to see what it can do. SDS011 particle sensor And of course, as I already have an HPMA115S0 ..read more

I today’s blog post I will show you how to make an Arduino based thermometer with 4-20mA communication bus. The project uses two Arduino Uno boards, one for the transmitter and one for the receiver. Each of the Arduino boards was equipped with one Arduino Uno click shield. The transmitter uses the DHT22 click board placed in mikroBUS socket #1 and the 4-20mA T click boards from MikroEkeltronika, which was placed in socket #2. Both click boards were configured for 5V logic level operation. By the way the 4-20mA T click is designed, the transmitter must be powered from an external source; it can ..read more

Last days I revisited some older projects on the blog looking for a source of inspiration, and I realized that I did not publish too many clock projects. Well, it’s time to fix this: today I will show you how to make a binary clock using one Arduino Uno, and one Arduino Uno Click shield, one 8×8 LED matrix B click and one RTC2 Click from MikroElektronika. As usual, when working with MikroElektronika click boards, the hardware part is deceptively simple: attach the Arduino Uno Click shield on top of the Arduino Uno board. Put the 4×4 B click in mikroBUS socket #1. Put the RTC2 click into mikroB ..read more

In today’s blog post I will revisit some aspects related to the 4-20mA current loop implemented with Arduino Uno boards, MikroElektronika Arduino Uno click shields and a pair of 4-20mA T and 4-20mA R click boards. In my previous blog posts regarding the implementation of a 4-20mA bus with MikroElektronika click boards and Arduino Unos I have described a precise calibration procedure (code provided). However, it has come to my attention that the proposed calibration procedure is a bit hard to follow. So, here there it is: a more straightforward, albeit less precise calibration procedure, that c ..read more

Today it’s finally the time to revisit the blog post on using the Honeywell HPMA115S0 particle sensor with an Arduino Uno board. The basics of the operation of the HPMA115S0 and a preliminary version of this code that works with Arduino Due are published in this blog post, so please take a few minutes and read it. After publishing that blog post, so many of you have asked me to come with a way to make this sensor work with an Arduino Uno. It’s relatively easy to do it, but one must overcome two minor issues: Albeit the HPMA115S0 is powered from a 5V supply, it uses 3.3V logic. To make it work ..read more

Ever since I wrote the blog post on sensing hydrogen sulfide using Arduino Due, I have received a lot of comments and messages about using the sensor with the more popular Arduino Uno. To use the sensor with the Arduino Uno, one must overcome two issues. The first issue relates to the fact that the sensor uses 3.3V logic and power, while the Arduino Uno is a 5V board. The second issue lies in the fact that Arduino Uno has a single serial port, and that post is commonly used for debugging. Overcoming these two issues is relatively easy. To solve the logic level issue, one can take 3.3V power fr ..read more

This blog post is a tutorial making a capacitance meter using the C-meter click onboard one Arduino Uno click shield from MikroElektronika and one Arduino Uno (or compatible) board. Of course, considering the simple design of the C-meter click, one can follow this tutorial and build the capacitance meter from scratch. This simple project can be used to display only the capacitance; it doesn’t measure other parameters such as leakage, equivalent series resistance (ESR), and inductance. A quick look at the C-meter click schematic reveals an astable oscillator built with the popular NE5 ..read more

Long time, no see. I’ve been quite busy, and I had little time to write here. And I’ve spent the last days fighting to get one Voltmeter click to work with an Arduino Uno, as a prerequisite to the next project that will be featured on the blog. The Voltmeter click board I’m writing about is a mikroBUS add-on board for measuring voltage in an external electric circuit. The board can measure DC only, and the advertised measurement range is -24 to 24V. A very nice piece of hardware, but I have found that the accompanying code example is utterly wrong. If one looks at the code example one sees the ..read more

As its name suggests, the LED Flash click is a high power LED flash unit based on the 4-Amp very high−current integrated flash LED driver CAT3224 from On Semiconductor. A dual cell capacitor can provide current pulses of up to 4A, with a duration up to 300ms, far beyond the current capability of today’s batteries. The CAT3224 features a 1x/2x charge pump which charges the stacked supercapacitor to a nominal voltage of 5.4V. The nominal charge current is determined via an external resistor, and an active balance circuit ensures that both capacitor cell voltages are balanced. It sounds complicat ..read more

An essential aspect of measuring air quality is to determine the number of small particles. That is, things smaller than 10µm and 2.5µm. Such tiny particles are roughly the size of a microbe and can penetrate the lungs,  causing many health issues. But how we can measure such small things? Most often, this is done via laser scattering: a laser light source illuminates small particles as they are pulled through the detection chamber. As these particles pass through the laser beam, the variations in light intensity are recorded by a photodetector. Those variations can be further analyzed to ..read more