Prextron CHAIN BLOCKS - Arduino Nano controlled Ultrasonic sensor that switches a motor wirelessly using 433MHz RF modules and a relay board.

 

Description

In this tutorial, I will be evaluating Prextron CHAIN blocks – a new system that allows you to connect your sensors and actuators to an Arduino NANO using clever 3D-printed prototyping boards that can be stacked sideways. This very modular system makes it easy to connect, disconnect and replace project components, and eliminate the “rats nest of wires” common to many advanced Arduino projects. CHAIN BLOCKS are open, which means that you can incorporate any of your sensors or actuators to these prototyping boards, and you can decide which specific pin on Arduino you plan to use. The CHAIN BLOCK connections prevent or reduce common connection mistakes, which make them ideal for class-room projects and learning activities.

I am going to set up a project to put these CHAIN BLOCKs to the test:
When I place my hand in-front of an Ultrasonic sensor, the Arduino will transmit a signal wirelessly to another Arduino, and consequently turn on a motor.

 

Parts Required:

You need the following Prextron Chain Blocks

• Arduino Nano x2
• 433MHz RF Transmitter and Receiver modules
• HC-SR04 Ultrasonic sensor
• RGB LED module
• Relay Module

You also need a few extra components:

• DC motor
• 9V battery
• 9V battery adapter

Please note: You may need to solder the module wires to the CHAIN BLOCK protoboard.

 
 

Arduino Libraries and IDE

This project does not use any libraries. However, you will need to upload Arduino code to the Arduino. For this you will need the Arduino IDE which can be obtained from the official Arduino website:
https://www.arduino.cc/en/main/software

 
 

ARDUINO CODE: RF Transmitter

 
 

ARDUINO CODE: RF Receiver

 
 

Fritzing diagrams for Transmitter

 

 

 

 

 

Fritzing diagrams for Receiver

 

 

 

 

Concluding comments

The purpose of this project was to evaluate Prextron CHAIN BLOCKs and put them to the test. Here is what I thought of CHAIN BLOCKS at the time of evaluation. Some of my points mentioned below may no longer apply to the current product. It may have evolved / improved since then. So please take that into consideration

 

What I liked about Chain Blocks

• The design is simple, the product is simple.
• Once the Chain Blocks were all assembled, they were very easy to connect to each other.
• I can really see the benefit of Chain Blocks in a teaching environment, because it simplifies the connection process, and reduces connection mixups.
• It was good to see that the blocks come in different colours, which means that you can set up different colour schemes for different types of modules.
• You can incorporate pretty much any sensor or Actuator into the Chain block which is very appealing.
• You also have the flexibility of choosing which pins you plan to use on the Arduino.
• Projects look a lot neater, because you no longer have the rats nest of wires.
• The Blocks lock into each other which means that they are much easier to transport/carry.

 

What I did not like about Chain Blocks

• In most cases, the Chain Block protoboard lanes were not numbered, which increased the chances of making mistakes when soldering
• The need to solder modules to the protoboard, may be a discouragement for some people.
• I would have liked a choice of different size Chain blocks. Some of the sensors did not fit nicely into the Square blocks.
• Prextron really need to work on their website if they plan to get serious with this product: Webpage has incomplete functionality or irrelevant links etc etc.

 
 
 

Thank you very much to Prextron for providing the CHAIN BLOCKS used in this tutorial, and allowing me to try out their product. If you are interested in trying them yourself, then make sure to visit them at:

 
 
 
 
 

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Description: Prextron CHAIN BLOCKS - Arduino Nano controlled Ultrasonic sensor that switches a motor wirelessly using 433MHz RF modules and a relay board. Rating: 3.5 Reviewer: Unknown ItemReviewed: Prextron CHAIN BLOCKS - Arduino Nano controlled Ultrasonic sensor that switches a motor wirelessly using 433MHz RF modules and a relay board.

433 MHz RF module with Arduino Tutorial 3

 

There are 4 parts to this tutorial:

• Part 1: Testing the 433 MHz RF transmitter and receiver
• Part 2: Receive and interpret code from an RF remote
• Part 3: Transmit a known 433 Mhz RF code to a 433 Mhz RF device - ** you are here **
• Part 4: Record and play back a 433 Mhz RF remote signal

To get the most out of this tutorial - it is best to start at tutorial Part 1, and then progress to Part 2 then Part 3 and then do Part 4 last. Doing the RF tutorials in this order will help you to understand the process better.

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Project 3: RF Remote Control Emulation

In the first tutorial, I introduced the 433 MHz Transmitter and Receiver with a simple sketch to test their functionality. In the second tutorial, the 433MHz receiver was used to receive a signal from an RF remote. The RF remote signal was coded based on the pattern and length of its HIGH and LOW signals. The signals received by the remote can be described by the code below:

 
Code comparison table

The RF remote that I am using transmits the same signal 6 times in a row. The signal to turn the light on is different from that used to turn the light off. In tutorial 2, we were able to "listen to" or receive the signal from the RF remote using the RF receiver. I thought it would be possible to just play back the signal received on the Arduino's analogPin, but the time it takes to perform a digital write is different to the time it takes to do an AnalogRead. Therefore it won't work. You need to slow down the digitalWrite speed.
I would like to find out if it is possible to apply this delay to all 433 MHz signal projects, however, I only have one 433 MHz remote.

If the delay in your project is the same as mine (or different) I would be keen to know - please leave a comment at the end of the tutorial.

We are going to use trial and error to find the optimal digitalWrite delay time. We will do this by slowly incrementing the delay until the transmission is successful. The transmission is considered successful if the fan-light turns on/off. All we have to do is count the number of transmissions until it is successful, then we should be able to calculate the delay.

 

Parts Required

• Arduino UNO or compatible board
• Breadboard
• Wires
• RF Module (433 Mhz) - Transmitter and Receiver pair 
• Mercator Ceiling Fan/Light with Remote

 

The Transmitter Fritzing Sketch

 
 

RF Calibration - Arduino Sketch

I used an array to hold the RF code for light ON and light OFF. Each number within the code represents a specific sequence of HIGH and LOW lengths. For example, 2 represents a SHORT HIGH and a LONG LOW combination. A short length = 3, a long length = 7, and a very long length = 92. You need to multiply this by the timeDelay variable to identify how much time to transmit the HIGH and LOW signals for.
The short and long lengths were identified from the experiments performed in tutorial 2 (using the RF receiver). Each code is transmitted 6 times. The LED is turned on at the beginning of each transmission, and then turned off at the end of the transmission. The timeDelay variable starts at 5 microseconds, and is incremented by 10 microseconds with every transmission.
In the video, you will notice that there is some flexibility in the timeDelay value. The Mercator Fan/Light will turn on and off when the timeDelay variable is anywhere between 75 and 135 microseconds in length. It also seems to transmit successfully when the timeDelay variable is 175 microseconds.
So in theory, if we want to transmit a signal to the fan/light, we should be able to use any value between 75 and 135, however in future projects, I think I will use a value of 105, which is right about the middle of the range.

Video

  Now that I have the timeDelay variable, I should be able to simplify the steps required to replicate a remote control RF signal. Maybe there is room for one more tutorial on this topic :)

Update: Here it is - tutorial 4
Where you can record and playback an RF signal (without using your computer).

Description: 433 MHz RF module with Arduino Tutorial 3 Rating: 3.5 Reviewer: Unknown ItemReviewed: 433 MHz RF module with Arduino Tutorial 3