'TinyRhythm'

Multichannel Midi-Triggerinterface with onboard digital drumsynth

The basic idea was to try to get the most out of the tiny13-controllers. I stumbled upon this device somewhere and was immediately inspired by its simplicity and possibilites. This simple 1€-8pin-chip with only 1kByte flashrom has 4 analog-to-digital converters onboard (!). This means you can very simply put 4 pots at its pins, add ground and 5Volt and start writing some code to produce audio signals which can later be tweaked in realtime by the pots.

Another reason for this project is the desire to know more about:

• digital to analog converters and reverse (ADCs and DACs)
• generating audio with a microcontroller
• developing a midi-to-trigger interface
• using pulsewidthmosulation for led-fading and audio-output
• saving data in eeprom
• clean hardware design without thousands of individual cables - i know :) 'clean' would be to make a PCB with eagle but, well , this is still all prototyping.

Developing-thing

The tiny13 only got 8 pins which means its hard to led pins out for in service programming. in addition, one of the beloved ADCs shares the reset-input. If we want to use this fouth converter we must set the disable-reset-fuse. But then we only can flash the divice by serial, highvoltage-programming. I use the stk500 developmentboard to keep things simple and prevent confusion about flashing.

I made this little development addon to easily send voltages to the adcs while the tiny13 is still on the development board. The PB0 and PB1 are also led out.

a little helper for developing the tiny13-drummodules

Base board

The base board is the heart and brain of the TinyRhythm.

• convert Midi-Notes into digital Triggers
• DAC-converter to convert digital into analog triggers
• powersupply for the whole thing
• central point to spread triggers and ausio to daughterboards

... more info on the baseboard

the finished baseboard

Mixer-/Triggerindicator  board

• mix 8 audiochannels to 1 outputchanel
• add an accent to the outputchannel
• accent can be adjusted in length and depth

... more info on the mixerboard

the board with audiomixer and led-drivers for 8 trigger-indicators

Board for individual outputs

• jack for each instrument

Neat housing

it should be cheap and it should look nice.

... more on casing the whole thing

Module 1 : Bassdrum 1

• everrunning neverstopping squarewaveoscillator inside the tiny13
• digital envelope for PAOWWW instead of POWWW
• analog lowpassfilter
• analog VCA with analog envelope

...more info on the bassdrum 1

Module 2 : Snaredrum

• totally digital
• shifted noise, tunable from dark to bright
• digital envelope for bend of square and noise
• blendable from noise to square
• output only ON or OFF - no fading - sidstyle

... more info on the snaredrum

Module 3 : HiHats

• shifted noise, tunable from dark to bright
• 6 different ringing-oscillator-spectra
• analog, tunable highpassfilter
• output only ON or OFF - no fading - sidstyle

... more info on the hihats

Module 4 : Cymbal / Cowbell

the most complicated module yet:

• 3 oscillators with different tunings for 3 noisespectra and 3 different cowbell-tunings
• tuneable shifted noise
• analog vca with envelope
• bandpassfilter tunes by lightsensitive resistor
• pulsewidthmodulated LED modulating the bandpassfilter with different fadingmodes: lfo, envelope and sample and hold

... more info on cymbal/cowbell-module

Module 5 : modeled 808-Bassdrum with tiny13

planed features:

• sounds abit like the original
• digital triangle oscillator
• logarythmic, digital envelope for amplitude
• timer-pwm with lowpassfilter as DAC
• pots for Tune, Bend, Tone & Decay

... more info on the µController 808-Bassdrum

Module 6 : Clap / Guiro

• many different preset-burstmodes with several burst count & timespread combinations for wide spectrum of different sounds
• different waveforms/spectra
• roughly based on DR110-Clap (Reverb and filtersection)

... more info on the Clap / Guiro module

Module 7 : analog Maracas & Clave of Vermona ER-9

• no microcontrollers here :)
• very, very simple but good sounding voices
• just to have some soft enveloped noise percussion
• Maracas-Attack adjustable
• manual switch between voices

... more info on the Maracas / Clave module

Module 8 : analog 808-Clave / Noise-Rim / CR5000-Clave

• 808-clave-sources both tuneable from clave to conga
• 808-rim with noise as soundsource
• clave doesnt sound like the original but makes a nice electronic 'bec' :)
• voices switched by triggerstrength

... more info on the analog percussion module