Wireless Coupler Terminal Interface using AVR microcontroller

This is a Minimum Mass Wireless Coupler that connects a terminal, or PC running terminal software, to other Minimum Masss Wireless devices by means of a 1200 baud data channel at 181.818 kHz.
The basic Minimum Mass Wireless Coupler technology is described and links to other projects on this site that use the Minimum Mass Wireless Coupler are located on the web page, Minimum Mass Wireless Coupler.
Download the AVRStudio assembly source for the program: vlfterm2313.asm
Download the AVRStudio assembly source for the include file: vlfcw2313.inc
Wireless Coupler Terminal
The loop antenna goes around the perimiter of the circuit board.
The componenets inside the loop seem to have little effect on performance.
The purpose of the terminal interface is to allow my computer to communicate with Minimum Mass Wireless Coupler equipped devices using a terminal emulator program.  Consequently, the Base Unit is basically  an RS-232 interface and Minimum Mass Wireless Coupler.  The Base Unit is the larger enclosure in Photo 1. The RS-232 interface to the computer is 9600 baud, 1 stop bit, no parity, plenty fast to keep up with the 1200 baud maximum data rate from the Coupler.
The antenna is made of 12 turns of #30 enameled wire threaded through metal guide loops arranged around the perimeter of the board (See the photograph.) This antenna’s area is about 160% that of the prototype 5.5 cm loop so it  has a little more range for both transmitting and receiving.
To further increase the transmitter’s range, I used 220 ohm bias resistors (See the schematic, Figure 4). This sets the maximum peak current from the microcontroller’s output pin at about 23 milliamps, safely below the maximum current specified on the microcontroller’s data sheet. Since the antenna is resonant, the peak antenna current is greater than the microcontroller’s drive current, about 70 milliamps peak-to-peak in this cae.
For more detail: Wireless Coupler Terminal Interface using AVR microcontroller

About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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