The launch of the Genuino 101 with integrated Bluetooth Low Energy (BLE) and the Genuino MKR1000 with Wi-Fi connectivity has resulted in an explosion of interest in using Arduinos wirelessly, but there's still one stumbling block: neither are particularly cheap. The problem is exacerbated if, like us, you have a workshop filled with various older models of Arduino and Genuino which lack integrated wireless connectivity - which is why we're pleased to see Embedded Lab running a guide to simple, low-cost wireless communication between Arduinos.
Written by founder Raj Bhatt, the guide centres around low-cost amplitude shift keying (ASK) radio transmitter and receiver pairs. Available in 315MHz and 433MHz flavours, taking a chunk of the licence-free industrial, scientific and medical (ISM) spectrum band available in most countries around the globe, these modules are easily connected to almost any model of Arduino and simply integrated into any existing sketch or project.
Raj's example project for the ASK radio modules uses the popular DHT22 sensor to read temperature and humidity from a remote Arduino Nano, which is then transmitted to a receiving Arduino connected to a re-purposed Nokia 5110 liquid-crystal display (LCD) to display the reported information. Using Mike McCauley's VirtualWire library data is transmitted from the remote Arduino to the display module automatically - and with a range Raj claims more than capable of reaching from one corner of his house to the other, despite the low-power nature of the radio modules in use.
While point-to-point radio communication systems like Raj's aren't always suitable for all projects - they can be difficult to make work in anything other than a simple transmitter-receiver model, such as having multiple transmitters all communicating with a single receiver, and are ill-suited to high-bandwidth uses such as video transmission - it's a great way to get started at a very low cost, and an excellent introduction to working with radio modules.
This article explores an easy wireless communication setup between two Arduinos using low-cost ASK RF transmitter and receiver modules that are readily available in the market. They are found in different shapes, but functionally they are all same. Both Tx and Rx modules contain a single data line for input and output and support a low-speed Amplitude Shift Keying modulation for data communication.