Latest upgrades:

2016/04/12: First prototype ready and working.

2015/02/14: Initial version is working quite fine. I will definately develop this furher as easy to mount PCB. Stay tuned.


Arduino / Atmel ATMega328 based midi upgrade for DR55 replaces the TC5501 SRAM. It acts like the original RAM but it can also carry extra tasks for midi receiving and transmitting. Without midi connectors fitted, the operation of the DR55 remains the same as on stock DR55, so it's possible to use this as replacement of 9V battery killed RAM. 

New features are:

- Internal clock is rejected if the midi clock is received. Clock pulse triggers hihat as in original one.

- Patterns 7 and 8 (12 steps) has different prescale for midi clock keeping the bar tempo same as 4/4 patterns

- It responses the midi in notes. Accent is enabled if velocity is greater than 100.

- On internal playback mode the sequencer output is echoed to midi

- Amount of patterns are doubled. The bank is selected during the power up, by variation switch position (A or B).


First version running on Arduino Uno board