Design Aim

The Keyer PCB is made of two boards which is the framework for the STRAIGHT-KEY/PADDLE sounding side-tone as well as sending Morse code to radio. The boards offer flexibility and minimize wiring chores by hosting the following components:

• MCU board (Adafruit Metro-mini)
• LCD display (generic 16x2)
• USB power + serial data connector
• key/paddle input, output & speaker port

Another important factor in design is allowing the builders freedom in terms of the form-factor flexibility, placement of the components, and if to add/eliminate some parts at will. A few examples are if LCD module to be built-in, the power indicator, green LEDs, if to eliminate the LCD backlit all the time, etc. Thus, the boards can be used for other purpose than the KEYER project entirely.

The photos show one of the form-factors we came up with building a CW keyer. More details are available in the USER GUIDE document including schematics, how to use the firmware (available as compiled hex file), and viewing the key/paddle actions on LCD display as well as on the PC detailing the precise key/paddle actions.

Also built-in in the firmware is Farnsworth CW-Trainer between 5 to 20 WPM where characters are sent to a local speaker, if one is provided. Else, the same can be sent to the user's radio as if one is working in CW mode on the radio directly.

Boards

All parts are through-hole type making it easy to build

1) Main board accommodates the user supplied,

• controller board (Metro-mini)
• standard LCD display unit
• supporting components for a keyer
• interface headers & cabling

2) Input/Output board accommodates the user supplied,

• 3 jacks for straight-key, paddle & speaker
• USB-C (female) breakout board
• trimmers for volume, LCD contrast
• cable headers and other pads+pins

What makes it unique

Since each board has different functions but working together they need to communicate. They can be, however, located anywhere to fit the form-factor user choose to have. That is the premises of having separate boards dividing the tasks.

When the boards are separated, the cabling must be done between the 10-pin headers. Else, the two boards can be hard soldered to act as a single board. The LCD display module augmented is the same idea that the main board can be piggybacked on the display module or connected via 12 hookup wires.

As to other parts, such as switches & LEDs, they are not mounted on the PCB offering freedom to locate the parts and boards where it is most logical and convenient, thus fabricating an enclosure the way the builder wishes.

Assembling & Testing

By providing the schematics and firmware, the maker is giving the builder all the information they need to build/modify a functioning keyer. The firmware will also help to ensure that the PCBs & assembly are done correctly, as it will check all the necessary components and connections. Additionally, component level details are shown on the schematics included in the 'Documentation' link below.

Should a user wish to have other than Metro-mini controllers, one can fabricate a conversion adaptor to fit into the main board very easily and inexpensively, yet, having all the peripheral resources available. Of course, by doing so, it requires a different firmware.

We are offering the PCBs only at this time but for any reason the builder wishes to have stuffed boards or an assembled keyer, please send an inquiry email to us.

Now, the user is ready to write one's own firmware displaying text & more, and ample I/O ports making a CW keyer or any other similar project.