Get your FREE Ultimate Guide - How to Develop Your New Electronic Hardware Product Programming the Central Security Controller While the I/O pins are 5V tolerant, connecting the VCC of nRF24L01 with Arduino’s 5V regulated supply could damage your transceiver. WARNING: Unless you’re using an external base module with a voltage regulator and bypass capacitors, all nRF24L01 transceivers are 3.3V modules. This capacitor helps to supply any fast current transients required by the RF module. To improve the signal strength and reduce the packet loss, I recommend connecting a 10μF electrolytic capacitor between the VCC and GND of the transceiver module. Since most nRF24L01 modules don’t have the pins labelled on the circuit, here’s the pinout diagram for your reference: Lastly, I have connected the nRF24L01 transceiver module with the Arduino Uno in the following configuration: The positive leg of the piezo buzzer is connected to digital I/O pin 7 of the Uno, while the negative terminal is connected to Arduino GND. Here’s what the hardware prototype of our central security controller looks like:Īs you can make out from the above sketch, I have connected the Tx and Rx of the SIM900A module with digital pins 2 and 3 of the Arduino respectively. Central Security Controller Hardware Design To turn the alarm off, the owner can either send a pre-configured text message from the registered number or simply press the disarm button. As soon as the code for the panic signal is received from the remote, the controller triggers the buzzer and notifies the owner via text message. The Arduino maintains an active radio link with the panic button (via nRF24L01) and constantly listens for the coded signals. As you can see from the above block diagram, the central security controller has a single Arduino MCU that’s connected to the GSM module (via the UART Tx-Rx lines), and a piezo buzzer. High-Level Overviewīefore going into the nitty-gritty of the hardware design and code, let’s first understand how the setup works on a higher level. In case you’re unable to get your hands on a SIM900A module, you can use any equivalent modules (SIM800A/SIM800L) or even opt for the slightly expensive Arduino GSM shield. Lastly, I have used the SIM900A GSM/GPRS module for sending/receiving text messages. Although I have used the basic transceiver model for prototyping, you can always pick higher variants with a power amplifier and an SMA antenna that offer an extended wireless range (~1km). They operate using a 2.4 GHz RF carrier just as with Bluetooth and WiFi. The central security controller runs on the Arduino UNO, while the panic button remote operates on the Arduino Nano.įunctionally, there’s not much difference between the boards (you can really use any Arduino board), but I chose the Nano, as it’s smaller in size and ideal for prototyping the panic button remote circuit on a breadboard.įor establishing the radio link between the controller and the panic button remote, I have used nRF24L01 transceiver modules, which are pretty cheap and reliable. ► 2x 10μF electrolytic capacitor (for removing noise)įor the project, I would be using two different Arduino MCU boards. ► 2x nRF24L01 2.4 GHz Wireless Transceivers Programming the Central Security Controller.Here’s What You’ll Need for the Project:.
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