Using a Soil Moisture Sensor with Arduino

Hi guys, welcome to today’s tutorial. Smart farms are becoming very popular as everyone is beginning to see the benefits in terms of crop health and yield and I know a lot of people that will be interested in smart farm automation. That’s why today, we will be looking at how to use a soil moisture sensor with an Arduino to determine the moisture content in the soil.

Soil moisture is generally the amount of water that is held in spaces between soil particles. It’s is a very important factor that determines the growth of crops and their health.

Instead of the old gravimetric method of measuring soil water content, the soil moisture sensor measures the volumetric water content indirectly by using other properties associated with the soil. The soil moisture sensor used for this tutorial uses electrical resistance of the soil to determine the soil humidity. The electrical resistance of the soil reduces with increase in the amount of water in the soil. The electrical resistance in the soil, however, increases with reduction in the amount of water in the soil. The sensor consists of a probe and a comparator with an adjustable potentiometer which can be used to set the sensitivity of the sensor.

Using a Soil Moisture Sensor with Arduino – [Link]

Use a Comparator or Op-Amp to Simplify Light Dependent Resistor Output

If your project calls for light sensitivity, it’s hard to beat light dependent resistors (LDRs), also known as photoresistors. They’re available for a few cents each, and their resistance varies based on how much light they receive. In the dark, these devices produce resistances in the megohm range, and can fall to hundreds of ohms or even less when exposed to sufficient light. You first instinct when prototyping this type of device is likely to use an analog input on an Arduino or similar dev board to sense voltage levels. This works quite well in many situations, but you may also want to consider a comparator or operational amplifier (op-amp) to turn this analog input into a simple on/off signal. You could also use one of these components by itself to produce a usable output without the use of a microcontroller.

LDR Analog Input to Microcontroller

An LDR setup for Arduino Analog Input. Illustration: Jeremy S. Cook in Fritzing

First, let’s examine how a microcontroller would see an LDR input. Using the circuit illustrated in the figure above with an Arduino Uno, an LDR is attached to 5VDC, then routed to the analog input A0. Voltage at the intersection of A0, the resistor, and LDR is divided between the fixed resistor and LDR, which decreases its resistance as light is applied. Voltage at this analog input increases with the lowered resistance in proportion to the amount of light the LDR sees.

The Arduino board is thus able to sense the resulting voltage level and convert it to an analog value. A threshold can be setup to respond to different light levels as on or off, or the analog signal can be used for proportional control. Note that the resistor in this illustration is just a placeholder; it would need to be adjusted based on your LDR sensitivity. You can also use a trimming resistor to tweak output values as needed.

Comparator Digitizes Analog Signal

What if you need light input, but just want an on/off value? Analog inputs can handle this programmatically, but if you’re using an Arduino Uno you’re restricted to the 6 analog pins. There’s also the normally minor issue of additional program complexity. If you need more performance out of your setup, you could turn to a comparator, or operational amplifier (op-amp) set up to act as one, to convert this analog value into a simple on/off signal.

Caption: An LDR and LM358 Op-amp setup to detect light as a binary signal to an Arduino Uno Illustration: Jeremy S. Cook in Fritzing

For example, if you were going to use an LM358 op-amp and LDR to detect light, you could tie the V+ (pin 8) to the 5V supply of your Arduino, ground (pin 4) to the Arduino’s ground, and output A (pin 1) to a digital pin on your Arduino board. The inverting input (pin 2) would be hooked to a voltage divider between +5V and ground, and your LDR would be setup in a voltage divider on the non-inverting input (pin 3). Here the LDR would act as the resistor from +5V to the op-amp input, and the set resistor would run to ground.

This will give you an on/off input to your Arduino without mucking about with any extra programming. Note that because of the way this op-amp operates, the output will be less than 5V, but will be sufficient to trigger the needed input. Obviously this will add some wiring complexity—more work than a few lines of code—so it’s not ideal in all situations.

Comparator Sans Arduino

You’re probably wondering at this point why you wouldn’t simply get a dev board capable of more analog inputs if that’s what is needed. After all, hooking up additional wiring or adding more complication to your PCB isn’t trivial. Certainly there are some applications that call for this, but for really simple electronics, you may not need a microcontroller at all.

Caption: An LDR and LM358 Op-amp setup to turn an LED on when there isn’t sufficient light available.
Illustration: Jeremy S. Cook in Fritzing

One such simple application would be a light that you want to come on when the ambient light drops below a certain threshold. In this application, you’d want to put the resistors only voltage divider on the non-inverting input (pin 3), while the LDR voltage divider would be placed on the inverting input (pin 2). This would cause the voltage on pin 2 to be larger than pin 3 when the light is on, turning the output (pin 1) on when there isn’t enough light.

Of course LDRs are but one type of sensor, and there are many models of op-amps and comparators with different characteristics available depending on your needs. If you’re just starting out with sensors and electronics, using a dev board like an Arduino is a great choice. As you advance in your knowledge, you might also consider analog electronics for your builds. While not appropriate or necessary for every project, it’s a great tool to have available when purely digital processing doesn’t quite fit your application.

Jeremy S. Cook and Zach Wendt are engineers who enjoy sharing how electronic components can best impact applications. Jeremy writes for a variety of technical publications. Zach works for Arrow Electronics, a major supplier of Arduino products.

Taking Advantage of Embedded FPGA (eFPGA)

By Geoff Tate, CEO of Flex Logix, Inc.

Whether you are designing an SoC, MCU or other chip, the one common heartache is “freezing RTL.” Up until that point, it’s no problem making a change or update, but once it’s frozen, the chip design is “locked in.” A change after that point could require a new spin that is not only costly, but can also significantly delay the chip development schedule.

Now imagine what it would be like to have no deadline to freeze RTL. What chip designer would not want that? The good news is this is now possible using embedded FPGA (eFPGA). With eFPGA, designers have the flexibility to make changes at any point in the chip development process, even in the customers’ systems. While this is beneficial to any chip design team, it is especially beneficial for applications such as data centers, networking, deep learning, artificial intelligence, aerospace and defense.

What is eFPA?

Many people think that eFPGA is the same as traditional FPGA such as those offered by Xilinx and Altera. This is not the case at all. While the technology is similar, eFPGA requires no SERDES and PHYs because on-chip signaling is very fast. Density is also very similar, although some eFPGA platforms are much better than others so designers need to do their homework and shop around for the best platform. The real difference is the users. FPGA chips are used primarily by systems companies, with some in high volume. eFPGAs are used primarily by chip companies who need to integrate a small amount of FPGA-like flexibility into their chips.

An FPGA combines an array of programmable/reconfigurable logic blocks in a programmable interconnect fabric. In an FPGA chip, the outer rim of the chip consists of a combination of GPIO, SERDES and specialized PHYs such as DDR3/4. In advanced FPGAs, the I/O ring is roughly 1/4 of the chip and the “fabric” is roughly 3/4 of the chip. The “fabric” itself is mostly interconnect in today’s FPGA chips where 20-25% of the fabric area is programmable logic and 75-80% is programmable interconnect.


The AAEON GENE-APL6’s onboard storage and dual LVDS support put you in the driving seat

(Taipei, Taiwan – May 3, 2018) – AAEON, one of the world’s leading developers and manufacturers of embedded platforms, launches the GENE-APL6, a rugged subcompact motherboard purpose-built for factory automation and transport applications.

Equipped with an Intel® Pentium® N4200 or Celeron® N3350 processor and DDR3L memory, the fanless GENE-APL6 features a solder-up design, which allows for the easy implementation of a heat spreader to channel heat from the CPU out through the chassis. Additional wide temperature support controls are available on request.

A wide DC input range of 9V to 36V allows the board to overcome fluctuations in power supply and continue running in the unstable environments of factory automation and in-vehicle systems. The GENE-APL6 has been further ruggedized with anti-vibration measures including onboard eMMC storage of up to 128G.

AAEON is a customer-focused company, and it responded to requests for dual LVDS support when designing the GENE-APL6. The low power consumption technology with high noise immunity is ideal for rugged applications, and an HDMI port can be installed as a custom option. Four USB ports, four COM ports, and Mini Card and mSATA expansion slots, give the board the flexibility to match its strength.

“By removing points of weakness, such as storage through expansion slots only, and by adding the features end users want to see, we’ve made the GENE-APL6 the strongest, most complete factory automation and in-vehicle motherboard on the market,” said Julie Huang, AAEON embedded computing division product manager.

Rutronik UK offers first integrated MEMS gas sensor from Bosch Sensortec

Integrated environmental sensors from Bosch Sensortec, the BME680, for wearables and mobile use, is available from Rutronik UK.

The Bosch Sensortec BME680 expands Rutronik UK’s portfolio to include the first integrated MEMS sensor measuring individually, highly linear, and precise, gas, air pressure, humidity, and temperature. The BME680 is an integrated environmental sensor specifically developed for wearables and mobile applications. It features a space-saving design and low power consumption.

The BME680 detects a number of different gases, including volatile organic compounds in paints containing formaldehyde, varnishes, paint strippers, cleaning agents, furniture, office equipment, adhesives, and alcohol. With accuracy of ±0.12 hPa and a TCO of 1.5Pa/K, the sensor features a precise barometer, says Rutronik UK and high-resolution and low-noise sensors for measuring humidity and temperature, making the BME680 suitable for home automation, indoor navigation, personalised weather stations, or sport and fitness tools.

The BME680 supports the I²C and SPI buses (three- or four-wire), is compatible with a wide range of VDD and VDDIO supply voltages, and can work in standard, forced, and sleep mode. It is supplied calibrated and an air pressure calculation can also be carried out at a later stage using the ACP 2.0 software from Bosch Sensortec.

The sensor is housed in LGA package measuring 3.0 x 3.0 x 0.95mm³. The design supports electromagnetic compatibility (EMC), longevity, and optimal power consumption in various operating modes, adds Rutronik.

To make the set-up process as simple as possible, standard settings for common applications such as weather monitoring, staircase/elevator detection, indoor navigation, and drop detection are already available. The data rate, noise, response time, and power consumption can also be individually adjusted.

The Bosch Sensortec BME680 is available on Rutronik’s e-commerce platform (where orders can also be placed directly).Rutronik UK operates as an independent company of the parent company, Rutronik Elektronische Bauelemente GmbH. It has a team of highly-qualified UK employees with broad experience of the electronics industry.

Rutronik Elektronische Bauelemente GmbH is one of the leading broadline distributors for semiconductors, passive and electromechanical components in addition to storage technologies, displays and boards and wireless products. The company primarily targets automotive, medical, industrial, home appliance, energy and lighting markets.

RAK8211-NB iTracker – An All Weather IoT Board designed for Asset Tracking with Bluetooth 5.0

In the last few years, we have seen a lot of love poured towards the hardware ecosystem especially hardware related to the Internet of Things applications (hardly would you find any board that doesn’t have one or two IoT offerings). Some boards give basic IoT functionality like providing you with a basic IoT connectivity interface with no extra add-ons while some boards goes the extra mile by providing more, RAK8211-NB iTracker is one of those boards.

RAK8211-NB iTracker

Rak Wireless, the Chinese based hardware company has recently launched a new IoT focused board called the RAK8211-NB iTracker based on the Quectel BC95-G NB-IoT Module, Nordic Semi nRF52832 Bluetooth 5 chip, and Quectel L70-R GNSS module. The Quectel BC95-G is a high-performance NB-IoT module which supports multiple frequency bands of B1/B3/B8/B5/B20/B28* with extremely low power consumption. The ultra-compact 23.6mm × 19.9mm × 2.2mm profile makes it a perfect choice for size-sensitive applications like the RAK8211-NB iTracker. The Quectel provides a flexible and scalable platform for migrating from GSM/GPRS to NB-IoT networks.

The RAK8211-NB is a module geared towards asset tracking and management due to its arrays of features, and it’s one of those board that supports the new Bluetooth 5.0. The board includes a vast array of connectivity options (NB-IoT, BLE 5.0 and GPS). The asset tracker module comes with five different sensors to monitor motion and environmental data, and can optionally be powered directly by a solar panel. It comes with accompanying sensors like an accelerometer, a light sensor and a barometric sensor. At the heart of the RAK8211-NB is the Nordic NRF52832 SoC. The nRF52832 SoC is built around a 32-bit ARM® Cortex™-M4F CPU with 512kB + 64kB RAM. The embedded 2.4GHz transceiver supports Bluetooth Low Energy, ANT, and proprietary 2.4 GHz protocol stack.

The RAK8211-NB module is Arduino friendly and can be programmed using the IDE. The board also provides SWD interface for programming the NRF52832 core. The combination of BLE and NB-IoT offers flexible low power consumption development along with a myriad of application option ranging from telemetry to live tracking and environment sensing. The RAK8211-NB iTracker provides applications in the following areas:

  • Vehicle location/fleet transportation management.
  • Safety monitoring of old/young children.
  • Animal protection and animal husbandry management.
  • Asset tracking and management.
  • Prototyping for NB-IoT Applications.

The below are some of the specifications of the module:

  • Connectivity
    • NB-IoT via Quectel BC95-G (Global) wireless communication module + SIM card socket
    • Bluetooth 5 via Nordic Semi nRF52832 Arm Cortex-M4F micro-controller (Arduino compatible)
    • GPS/GLONASS via Quectel L70 GNSS module
  • Sensors
    • LIS3DH ultra-low-power, high-performance 3-axes “nano” accelerometer
    • LIS2MDL ultra-low-power, high-performance 3-axis digital magnetic sensor.
    • Tilt sensor
    • BME280 pressure, humidity and temperature sensor
    • The OPT3001 intensity of light sensor
  • Expansion – 3x headers with SWD, 2x sensor out + tilt out (also usable as GPIO and analog inputs), 3.3V, GND, and reset
  • Power Supply – 3.5V to 18V via solar panel (P2) or battery (P3)
  • Dimensions – 43mm x 38mm x 18mm
  • Temperature Range – 40°C to +85°CBLE Features

The company provides instructions to use the module with the Arduino IDE, Espruino (JavaScript) and Arm Keil tools. The RAK8211-NB iTracker kit is available and sells for $98.40 + shipping on Aliexpress. Rak Wireless also offers another variant of RAK8211 with RAK8211-G based on the most of the same features, except GPRS is used instead of NB-IoT. It is sold for $87.40 + shipping.

BlkBox BB-E01P – The World’s Smallest ESP8285-Based WiFi Module

Back in March 2016, Espressif Announced the ESP8285 Wi-Fi Chip, a supposed killer of the favorite ESP8266 chip. The new chip is an ESP8266, but with the flash memory onboard –  1MB flash memory. Espressif’s ESP8285 delivers highly integrated Wi-Fi SoC solution to meet users’ constant demands for efficient power usage, compact design and reliable performance in the Internet of Things industry. With the complete and self-contained Wi-Fi networking capabilities, ESP8285 can perform either as a standalone application or as the slave to a host MCU. When ESP8285 hosts the application, it promptly boots up from the flash. The Chip is also ultra-small as compared to the ESP8266 making it suitable for applications like in wearables.

Taiwan based Blkbox may have designed the world’s smallest WiFi IoT module with their Espressif Systems ESP8285 based BB-E01P module which is pin-compatible with the ESP-01 module, and measuring just 10×14 mm. Several ESP8285 modules have been released, but the Blkbox version is probably the smallest ever. Itead Studio’s PSF-A85, an ESP8285 Wireless Module measures just 14mm*135mm, and even the Electrodragon ESP8285 WiFi module measures 15.5mm x 17.8mm. With this, the Blkbox module might be the smallest we currently have. The BB-E01P is the equivalent of the Blkbox predecessor BB-E01 with reduced dimensions.

BB-E01P ESP8285 Pinout

The following are the specification of the Blkbox BB-E01P ESP8285 WiFi module:

  • WiFi SoC – Espressif ESP8285 WiFi SoC with 1MB internal flash
  • Connectivity – 802.11 b/g/n WiFi with chip antenna
  • Expansion – 8-pin (2.54mm pitch) with Tx/Rx, CP, RS, GPIO0, GPIO2, 3V, GND (Same layout as ESP-01)
  • Interface – UART
  • Misc – Jumper supports Deep Sleep Mode (AT+GSLP)
  • Firmware Version: AT v1.6 / SDK v2.2
  • Power Supply – 3V -3.6V
  • Dimensions – 10 x 14 mm
  • Pin Pitch – 2.54mm

The Blkbox board is preloaded with the firmware version AT v1.5/SDK v2.2. Just like every other Blkbox boards, the module can be purchased on Tindie for $6.80 + shipping.

The third revision of the Raspberry Pi can best be summed up by the old adage of more of the same.

A Raspberry Pi SBC

The third revision of the Raspberry Pi can best be summed up by the old adage of more of the same. A faster processor and Power over Ethernet capability were advertised – OEMsecrets tells you what you need to know.

Raspberry Pi’s are always sold via the ecosystem. This is a promise which the foundation, by and large, manages to keep: if you use a sufficiently recent version of RaspBian so that the new SOC is supported, the same memory card can also be used in older versions of the process computer. When looking at the thing from the top, not many differences can be seen. The most important change is the addition of the four pin header for the Power over Ethernet hat: it might cause problems with some cases. Other than that, the physical dimensions remain the same.

The third revision of the Raspberry Pi can best be summed up by the old adage of more of the same – [Link]

RaptorLoc Pro – A versatile modular third hand system

The most capable and expandable third hand system for holding your projects is getting a major upgrade! Jotham McMillan writes:

Dear fellow Kickstarter Patrons, at various points in my life, I’ve built RC cars, messed with Arduino projects, built custom computers, assembled models, added LEDs to my snowboard and so on. A common thread in these projects was the need to hold pieces in place while I soldered, glued or painted my parts.

The usual solution is some type of third hand tool…and there are some good ones out there but none of them have the functionality that I was looking for and they often had compromises with the parts they use. My wife can tell you that I don’t like to compromise thus…

DSO-1000E/F Series – Four-channel oscilloscopes with bandwidth up to 250MHz

Conrad Business Supplies, a household name for the distribution of electronics items has added to its ever-expanding products a new set of Oscilloscopes made by Voltcraft. The oscilloscopes are four-channel, they are very well equipped and are particularly suitable for measurements in research and development departments, in laboratories and schools as well as for maintenance, repair and service tasks.

DSO1000E/F Series of oscilloscopes cover the bandwidths from 80MHz to 200MHz and provide the real-time up to 1GSa/s. Also, they have 7-inch color TFT LCD with a resolution of 800 x 480 pixels as well as Windows-style interface and menus for smooth operation. What’s more, the plenty menu information and the easy-to-operate buttons allow you to gain information as much as possible while measuring; the multifunctional knobs and the powerful shortcut keys help you save a lot of time in operation; the Auto Scale function lets you detect sine and square waves automatically. By using the three methods the oscilloscope provides (context-sensitive, hyperlinks, and an index), you may master all operations on the device in quite a short time so as to greatly improve your efficiency in production and development.

The digital oscilloscope is intended to be used for visualizing electrical magnitudes and signals. There are four independent input channels available for measurement. The measuring lead is connected to the oscilloscope via two BNC sockets. Integrated help system can be called upon the display. The signals measured can be displayed on display as well as on a PC when a USB cable is used. The oscilloscopes also have a USB interface for connecting an additional data memory, for example, a USB stick.

The Oscilloscopes can perform some of the following: FFT (Fast Fourier Transform), extensive trigger options, standard Oscilloscopes functionality, firmware loading from a USB stick, and many more. The available models of the oscilloscopes are listed below:

  • Model DA0-1084E :
    • 4 Channels
    • Bandwidth – 80MHz
    • Sample Rate – 1GS/s
  • Model DA0-1104E :
    • 4 Channels
    • Bandwidth – 100MHz
    • Sample Rate – 1GS/s
  • Model DA0-1204E :
    • 4 Channels
    • Bandwidth – 200MHz
    • Sample Rate – 1GS/s
  • Model DA0-1254E :
    • 4 Channels
    • Bandwidth – 250MHz
    • Sample Rate – 1GS/s

The oscilloscopes are available for purchase on Conrad with ranging price depending on the model.