Based on ATtiny2313 MCU, scans two manuals and one 25-note bass pedal through a series of 4014 CMOS shift registers (8x 4014 for keybeds with 61 keys, 3x 4014 for bass pedals). Scan time with 8 MHz crystal (for low power consumtion) is around 360 µs, though using a delay of 2 to 4 ms for debounce is recommended (see sources). Sends MIDI notes on channel 1 (Upper), 2 (Lower) and 3 (Pedal). Leave upper and lower inputs open (high level pullup) for bass pedal only. Base channel may be set by jumpers/solder bridges.
Simultaneous scanning of manuals up to 61 keys and bass pedals up to 25 keys with single switches, contact to ground. May be used with following products from KeyboardPartner UG:
https://shop.keyboardpartner.de/en/p/bass25-midi
https://shop.keyboardpartner.de/p/scan61-inline
https://shop.keyboardpartner.de/en/p/scan16-strip
Note: This low-cost design will not work with FATAR or verlocity-sensitive keybeds. If needed, use our MIDI Scan controller design.
Connects to HX3 boards, organs or expander by MIDI cable. MIDI output jack 5-pin DIN. Could be placed inside MIDI pedal, size 170 x 50 mm. Power supply by MIDI phantom supply or 9V wall wart (SNT9). To utilize the phantom supply, two jumpers on HX3 board must be set. Please see HX3 Mainboard Installation Manual.
Schematics to be found on http://updates.keyboardpartner.de/Files/index.php?dir=Schematics%20%28Schaltbilder%29
In case of Arduino IDE, you may have to copy include and lib directory contects into sketch directory. Anyway, we highly recommend using PlatformIO with VSCode for development!
Version Info:
- Optimized for very small MCUs, no buffering for MIDI Tx
- Fast scanning with direct I/O
- TODO: Changes for later use of ATtiny404 MCU,[env:attiny404] does not work yet
C. Meyer 11/2010 - 02/2026