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'My Morse Guide', an AVR Electronics Kit Project

My Morse Guide is an electronics kit aimed at young people. The kit delivers both some fun in soldering the kit together as well as having a kit for playing with Morse code. My Morse Guide is a project by Ivo PA1IVO, Leo PA0LEZ and Marianne, and is a successor to the successful Share Your Morse project for the Jamboree On the Air 2013 at Scouting Elfregi Zaanstreek. This page contains a technical description of the project.

My Morse Guide Morse Badge

English text Er is ook een pagina met algemene informatie in Nederlands aanwezig.

Main functionality

The My Morse Guide electronics kit delivers the following functionality after it is successfully soldered together. With the 'Key' key it is possible to send Morse code yourself with the kit, or an external Morse key can be connected via the PCB terminal block (short-circuit for key down).

Schematic

The schematic of the electronics is displayed below. Electronic scheme
Electronic schematic.

Component list

Share Your Morse Badge
Description Name/value Part(s)
AVR Microcontroller ATtiny85V - PDIP IC1
IC socket 8w IC socket machined contacts N.A.
Speaker 41.T70P015HLF Ls1
Battery clips Keystone 2468 N.A.
Batteries Panasonic Batteries
LR03XWA/B2
Bat1/Bat2
LED Multicomp OVL-3324 LED1
Capacitor 100 nF C1
Switches Alps SKHHARA010 Mijn Morse
Woorden
Key
ABC
PCB Terminal Blok 2WAY, 26-12AWG N.A.
Resistor 560 Ohm R1
Resistor 100 Ohm R2
Resistor 10k Ohm R3

Table 1: Component list.



AVR Selection

Share Your Morse Badge The heart of the logic of this kit is based on a small AVR microprocessor. The selection for a chip in the AVR range is only based on previous experiences with AVRs, and therefore the availability of software, programmers, and knowledge. A PIC microprocessor should probably also be able to do the job.

The AVR selection was based on the following criteria:

By using the AVR Compare Devices page (well done!) we selected the ATtiny85V, which has only 8-pins in a DIL housing, a supply voltage down to 1.8 Volt, and the maximum memory in this range.

Speaker Selection

We looked for a small speaker, being a speaker and not a piezo buzzer. With a real speaker you are able to change the tone frequency, which is not possible with a piezo. The speaker selection was based on the following criteria: It is hard to find small PCB mounted speakers that are not piezos. We found one at Farnell (it's really a speaker, we opened one ....). It clearly peaks in volume at the resonance frequency of 2048 Hz, but it is still usable a few hundred Hz above and below the resonance frequency.

Software

The AVR software was developed with Atmel Studio, and therefore written in the C programming language.

Pictures

My Morse Guide components
All (electronic) components to build one kit.



My Morse Guide PCB

Front and back side of the printed circuit board (PCB).



Connection external key

Connection for an external morse key and the empty battery holder.



My Morse Guide connected to a morse key

A My Morse Guide badge connected to a real morse key



AVR Dragon

Research and development for the My Morse Guide project.
An AVR Dragon programmer is used to perform high voltage serial programming (HVSP) to the AVR.
HVSP is required to be able to use the reset pin of the AVR as an extra input.



AVR Dragon

Zero-insertion-force (ZIF) connector together with the AVR Dragon in an enclosure.
Extra connection to the PCB for easy testing.



2014-2017 by Ivo Klinkert, PA1IVO - Contact