In this project, i performed serial communication using FSK (Frequency Shift Keying) with the help of IC TCM3105. I will explain you a brief explanation about FSK.
FSK a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal. The technology is used for communication systems such as telemetry, weather balloon radiosondes, caller ID, garage door openers, and low frequency radio transmission in the VLF and ELF bands. The simplest FSK is binary FSK (BFSK). BFSK uses a pair of discrete frequencies to transmit binary (0s and 1s) information.[2] With this scheme, the "1" is called the mark frequency and the "0" is called the space frequency.
Source : https://en.wikipedia.org/wiki/Frequency-shift_keying
The board i made was designed using Autodesk EAGLE using one layer printed circuit board. I will call this is IC TCM3105 Board Module. The schematic for the board and the board i designed can bee seen at the picture below. I will also attached the .sch and .brd file that i made at PCB folder. Beside the schematic i provide, you can also refer here.
To perform serial communication we need 2 devices, each acts as transmitter and receiver. I will explain each of this device separatedly.
In this project i used arduino nano as the microcontroller for transimtter that read the height data received from barometer sensor. The barometer sensor itself used I2C communication. The Tx and Rx pin of arduino nano will be connected to the TxD and RxD of the IC TCM3105 module. TxD and RxD means Transmitter Digital and Receiver Digital. Then the TxA and RxA will transmit the analog modulated signal through active speaker. TxA and RxA means Transmitter Analog and Receiver Analog. I connected active speaker and IC TCM3105 Board using 3.5mm audio jack. But you have to remember using this method will make around you a little bit noisy.
I also used arduino nano connected with IC TCM3105 board for the receiver. The difference is, for the receiver i used pre-amp mic to receive the analog modulated signal that had been sent. This pre-amp mic is connected to the 3.5 audio jack which also connected to TxA and RxA. The TxD and RxD of the IC TCM3105 Module is connected to the Tx and Rx pin of arduino nano. Then for the final step i just need to connect LCD with arduino nano. If everything went well, the data read from barometer at the transmitter would be also available in the LCD of the receiver.
You can see full diagram block of my project below. The serial communication is done through modulated analog frequency. The board i designed has 3.5 audio jack. If you want the board to act as transmitter just connect active speaker. If you want the board act as receiver just connect pre-amp mic. I only tested one-way communication in this project. I have a plan implementing this project in order to make my own telemetry device. Actually the active speaker and pre-amp mic can be replaced with long range radio device. This will greatly amplify the range of the serial communication. I am very open and if you have any question feel free to ask. Thanks.
