{"id":1718,"date":"2017-02-04T19:22:52","date_gmt":"2017-02-04T18:22:52","guid":{"rendered":"https:\/\/www.turborebop.net\/?p=1718"},"modified":"2025-01-23T21:44:26","modified_gmt":"2025-01-23T20:44:26","slug":"cirkulino-4","status":"publish","type":"post","link":"https:\/\/www.turborebop.net\/?p=1718","title":{"rendered":"Cirkulino 4"},"content":{"rendered":"

Cirkulino 4 is a midi sequencer based on Arduino UNO R3 development board. It is an advancement from previous ones – and is final. The pcb’s were ordered to be made to professional standards.<\/span><\/h3>\n

A double boot option for arduino was found – to launch it as a native midi device -> https:\/\/diyelectromusic.com\/2022\/03\/22\/arduino-and-usb-midi\/<\/a><\/p>\n

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mocoLUFA <\/strong>MIDI firmware for Arduino Uno -> http:\/\/morecatlab.akiba.coocan.jp\/lab\/index.php\/aruino\/midi-firmware-for-arduino-uno-moco\/?lang=en<\/a><\/p>\n

This is dual mode firmware for Arduino Uno with 16u2 Midi Serial interface chip. There are two modes in this firmware: USB-MIDI(MocoLUFA) and Arduino-Serial.
\nINSTRUCTIONS:
\n– Burn 16u2 on Arduino Uno (check original document) – Windows -> Atmel Flip
\n– USB-MIDI formware works as default
\n– To enable Arduino-Serial, add jumper to PIN 4(MOSI PB2) and PIN6 (grand) on ICSP connector of 16U2
\n– Reset is required to switch the firmware mode<\/p>\n

DESCRIPTION:<\/p>\n

NEW CIRKULINO SERIES: version 4 – chinese board
\n– smd 4051 on 8 pins used as IO switches -> switch=input \/ led=output
\n– only for 5V 16Mhz atmega 328 based boards: ARDUINO UNO R3
\n– 8 LEDs \/ 3 segments – segments of 8 steps programmable via switches
\n– default step programming is for both segments on midi channel 1 – the basic usage layer -> 8 steps
\n– variations of this via two top buttons for two midi channels and via two bottom buttons for three segments (1st segment: left button, 2nd segment: right button; 3rd segment: both buttons
\n– stop\/ reset button: brief push = reset sequence
\n– stop\/ reset button for pause=stop: longer push; also selective stop for a single midi channel: a combined push of one of the two midi channel buttons + stop\/ reset button
\n– mode button for forward, backward and palindrome (forth and back)- ping pong
\n– selective emptying of the single segment: selected segment switch + mode button<\/p>\n

ROTARY ENCODER:<\/p>\n

– rotary encoder with switch
\n– basic function: clock speed change
\n– to set some options use rotary switch to enter this state
\n– basic mode: sequencer mode: eight led switches select eight basic steps – over three segments
\n– melodic mode: eight led switches select eight notes to be used
\n– tonality select mode: eight led switches to select one of eight tonalities<\/p>\n

IO pins:<\/p>\n

– 10K-22K resistor in series with switches limits the load on pin when in output mode
\n– normally as output to drive LED
\n– additional Si diode in series with LED adds 0.7V to about 3V threshold LED – to have high level for reading (high for arduino UNO at 5V is around 3V)
\n– reading the switches is done in each loop very briefly:
\n+ switch to input, pull up internal resistor, read the state
\n+ turn off the internal pull up, switch pin back to output<\/p>\n

MULTIPLEXER:<\/p>\n

– analog multiplexer HCF4051 to read 8 switches and send to the LEDs the individual pwm values
\n– multiplexer combines readings (digitalRead()) and writings (analogWrite()) on digital pin (LED_PWM)
\n– multiplexer switched channel on-resistance is around 60 to 125 ohms – LED limiting resistor not needed
\n– read switches through multiplexer: internal pullup resistor on pin LED_PWM (20Kohms) pulls input to high
\n– resistor 10-22Kohms from switch to ground is current limiter when switch pushed and pin is set to write
\n– white, blue or pink LEDs because of the 3.4 to 3.6V threshold – high luminiscence LEDs needed\u00a0 because of high speed scanning
\n– additional Si diode on common cathode of all circle LEDs going to the ground – to work on laptops (lower USB 5V psu?)
\n– potentiometers: analogRead makes problems if slider on top – voltage equals Vcc!? Does not return values! Put a diode or 1K ohms resistor there
\n– or use only two terminals of 100K to 1Mohms potentiometers -> define internal pullup 20K resistors on analog inputs<\/p>\n

OUTPUTS:<\/p>\n

– USB-MIDI with mocoLUFA (MIDI firmware for Arduino Uno 16u2 chip – set baudrate to 31250 Hz ) is main data output<\/p>\n

OTHER<\/p>\n

– with two pots at the bottom set transposition of notes on two channels
\n– with two pots above set progressive variations of:
\n– notes and predefined scales
\n– steps and predefined rhythmic patterns?<\/p>\n

Concept view at Ljubljana Mini Maker Faire 2017: Cirkulino_print<\/a><\/p>\n

The previous versions…<\/p>\n

Cirkulino<\/a><\/p><\/blockquote>\n