TA3ZGR CW Keyer & Trainer

TA3ZGR CW Keyer is an ESP32-based amateur-radio Morse keyer, hand-soldered on perfboard. It began as a simple iambic keyer and grew into a full-featured Morse trainer that needs no computer once flashed. Every setting, message memory, training progress and lifetime statistic is stored on the device and survives power-off.

Highlights

Iambic keyer — modes A and B, adjustable weight, paddle L/R swap.
Self-decoder — decodes what you send on the OLED, with prosign labels (<SK> <AR> <BT> <AS> <KN>).
Radio-like sidetone — two audio engines on one pin: PWM buzzer, and a DAC sine wave with a raised-cosine envelope for a soft, click-free tone through a PAM8403 amp. Adjustable tone, volume and rise/fall.
Rotary-encoder menu — 5 categories, long-press to go back; interrupt-driven so no detents are missed.
Message memories — 4 slots + quick-CQ + a beacon (never overlaps).
On-device text editor — edit messages without a computer.
Koch / Farnsworth trainer — 9 modes, separate character speed, correct ARRL Farnsworth timing, adaptive weighting, a rolling-window level-up rule, lifetime accuracy stats.
WiFi + web panel + OTA — all settings in a browser, plus wireless firmware updates.
Radio key output — open-collector NPN; drives a rig's straight-key jack (QMX, Icom, etc.).

Training modes

Echo · Listen · Call · Word-recognition · Learn (crib) · Head-copy · QSO · Traffic (operating tokens) · Word (crib-based vocabulary). Level advancement is Koch-style: ≥90% over the last 20 attempts. Character speed is kept independent of effective speed, and the "highest level" record only rises in the crib-free Echo mode.

Hardware

GPIO	Function	Connection / note
32	dit — paddle (left)	INPUT_PULLUP, active LOW · common → GND
33	dah — paddle (right)	INPUT_PULLUP, active LOW · common → GND
34	Pot — WPM	wiper · input-only pin
25	Sidetone (DAC1)	audio chain → PAM8403
27	Key-out (radio)	2.2k → NPN base → TRS jack
26 / 14 / 13	Encoder CLK / DT / SW	INPUT_PULLUP
21 / 22	OLED SDA / SCL	SSD1306 128×64, I²C 0x3C

Audio chain — DAC → amplifier

ESP32                                   PAM8403          4-ohm SPEAKER
GPIO25 --[1k]--+----------[1uF]--> IN L    VCC --- +5V     L+ --+
 (DAC1)        |                           GND --- GND      L- --+
            +-[22nF]-+
            |        |   Speaker BETWEEN L+/L- (BTL, never to GND)
         [1k tune]  GND  Add 1000uF + 100nF across VCC-GND (recommended)
            |
           GND

Radio key output — open collector

GPIO27 --[2.2k]--+--- B --+
                 |        +- C -----------> TIP    = rig key (+)
              [10k]       +- E -----------> SLEEVE = GND
                 |                           RING   = unused
                GND    Set the radio to STRAIGHT-KEY mode

Open source

All firmware, the schematic and 3D case files are on GitHub under the MIT license: github.com/innteger/ta3zgr-cw-keyer. Built with PlatformIO; the ESP32 Arduino core is intentionally pinned to 2.0.17. Use it, learn from it, build your own — 73!