S3 handheld revA

Handheld Robo DJ

A pocket robot-voice DJ on an ESP32-S3. SAM (the 1982 Software Automatic Mouth speech synth) pre-renders a bank of words into memory, and a "turntable deck" plays, scratches, stutters and reverses them over a drum machine, with a 16-step sequencer, granular and vocoder voice effects and a sci-fi HUD on a 128x128 OLED. Four buttons, one speaker.

The board is a single-sided PCB designed to be milled on a desktop CNC (all copper on the bottom, big pads, no jumper wires). The modules plug into female headers, so there's no SMD soldering.

What's in here

Parts

Pinout

Build the firmware

1. Arduino IDE (or arduino-cli) with the ESP32 core 3.x and the U8g2 library.
2. Board settings: ESP32S3 Dev Module, USB CDC On Boot: Enabled, PSRAM: QSPI PSRAM (it runs without PSRAM, with fewer words). arduino-cli FQBN: esp32:esp32:esp32s3:CDCOnBoot=cdc,PSRAM=enabled
3. Open firmware/handheld_robodj/handheld_robodj.ino and upload. Flash handheld_bringup first if you're bringing up a fresh board.

arduino-cli compile --fqbn esp32:esp32:esp32s3:CDCOnBoot=cdc,PSRAM=enabled firmware/handheld_robodj
arduino-cli upload  --fqbn esp32:esp32:esp32s3:CDCOnBoot=cdc,PSRAM=enabled -p COMx firmware/handheld_robodj

Tips:

• The OLED uses the U8G2_SH1107_PIMORONI_128X128 constructor. The generic SH1107 one shifts the picture by 32 px.
• If the SuperMini sits silent after an upload, press its RST button. The auto-reset can leave it in the bootloader.
• Intermittent buttons on a milled board usually turn out to be a solder bridge between neighbouring 2.54 mm pads.
• handheld_bringup prints to Serial every 250 ms: run it with a serial monitor open.

Controls

Diamond: UP = SHIFT, LEFT = VOICE, RIGHT = BEAT, DOWN = FX. Live hits play instantly. With REC on they're quantized into the 16 steps.

• Voice FX: CLEAN, CRUSH, ECHO, GRAIN (slow cloud of grains at mixed pitches), SWARM (dense detuned robot choir), VOX (16-band vocoder on a chord, words stay clear), CHOIR (pure vocoder).
• Scratch styles: BABY, CHIRP, TRANSFORM, TEAR, FLARE.
• Robot voices: ROBOT, SAM, ELF, E.T., STUFFY, OLD LADY.
• Words: HELLO, ROBOT, YEAH, ERROR, DANCE, BEEP, BOOP, SYSTEM, ONLINE, WOW, FRESH, SCRATCH, ONE-FOUR, OH NO, COMPUTER, PARTY, FUNKY, AWESOME, DOES NOT COMPUTE. Edit bank[] in the sketch to make it say anything.

Make the board

The PCB is single-sided with all copper on B.Cu, made for isolation milling. The Gerbers in hardware/cnc/ also work at a board house as a 1-layer board.

Milling order (details in hardware/cnc/CNC_CHEATSHEET.txt): 0.1 mm 20° V-bit isolation, 1.0 mm drill, 2.0 mm drill, then V-bit outline score. The .nc files are ready to run on a GRBL machine. The drill files are already patched by fix_drill_spinup.py, which fixes the spindle start for GRBL laser mode. To regenerate with FlatCAM, set the path at the top of load_and_mirror.tcl and run it (File > Scripting > Run Script). It mirrors the board, because the copper is on the bottom.

Before milling, print PRINT_1to1_fit_test.pdf at 100% and check your modules against it. The OLED and joystick outlines were measured from photos.

Credits and license

• SAM (Software Automatic Mouth) by Mark Barton / Don't Ask Software (1982). C port by Sebastian Macke, ESP8266SAM by Earle F. Philhower III. The C core is bundled in firmware/handheld_robodj/.
• U8g2 by olikraus; esp-dsp and the ESP32 Arduino core by Espressif.
• Co-created by Mark Hellar and Claude (Anthropic). PCB milled and soldered by Mark Hellar.

Licensed under the GNU GPL v3 (see LICENSE), the same as the bundled SAM core.