A comparative study of Microprocessors and Microcontrollers in musical instruments.

Musical instruments work by outputting an electrical, electronic or digital audio signal that ultimately is plugged into a power amplifier which drives a loudspeaker, creating the sound heard by the performer and listener. They must include a user interface for controlling its sound, often by adjusting the pitch, frequency, or duration of each note. Evolving through the ages it is increasingly common in electronic musical instruments to separate user interface and sound-generating functions into a music controller (input device) and a music synthesizer, respectively, with the two devices communicating through a musical performance description language such as MIDI or Open Sound Control, microprocessors and microcontrollers.

·       Microprocessors play a significant role in musical instruments, they are used to modify volume, attack, decay, and use special effects like vibrato. Basically it is used synthesize music after sampling is done. The first musical instrument with embedded microprocessor was:

      PROPHET-5(1978)

It was the world’s first fully-programmable polyphonic analog synthesizer. The Prophet-5 set the standard for programmable poly synths. Even today, virtually all poly synths can trace their designs back to this ground-breaking instrument.

Due to lack of compatibility between synthesizers from different manufacturers, the technology got evolved to MIDI(Musical instrument Digital Interface). The Prophet-600 was the first MIDI-equipped instrument. It featured a voice architecture similar to the Prophet-5, as well as a built-in arpeggiator and sequencer.

·       Microcontrollers usually take the form of a single IC that contains these basic parts:
1. CPU - a microprocessor (4-bit or more)
2. non-volatile flash memory --- this holds the program to be run.
3. RAM - random access memory (volatile memory for data storage)
4. EEPROM - Electrically erasable programmable read-only memory 
    used for non volatile storage of program data
5. GPIO pins - General purpose in/out pins - used to interface with switches, LEDs etc etc.
Microcontrollers are also able to bridge the divide between digital and analog. So we can use them in the world of analog synths.

     There are many examples of microprocessors being used in synthesisers:

Motorola produced the 6800 in 1974. It's a 8-bit microprocessor. The 6800 was used in the Fairlight CMI series II.

Texas Instruments produced the TMC0281 Speech Synthesizer in 1978. The TMC0281 was the world's first single-chip speech synthesizer.

Zilog  made the Z80 microprocessor in 1976..  

Synthesizers that used the Z80 include: Roland Jupiter 8, Sequential Circuits Prophet 5 & 10, Sequential Circuits Prophet 600, Roland MC4, E-mu 4060, Roland MSQ700, Oberheim OB-8, MemoryMoog, Emulator I and II, Akai 2700, E-mu SP-1200, E-mu Drumulator, Sequential Circuits Drumtraks.

                                                                                                                                     

Microchip Technology introduced the PIC 16C84 Microcontroller in 1993. The PIC 16C84 used a new type of memory called EEPROM (electrically erasable programmable read-only memory).

 The most common microcontrollers used in modern day synths:

                1.  Atmel (AVR, ARM, Arduino, ATtiny, ATmega, ATxmega, AT89, AT90, AT91)
     Eg.

     >Mutable Instrument--Branches (ATMEGA88PA), Grids (ATMEGA328P), Edges (ATXMEGA32A4U), Shruthi - ATMega644p

     >ADDAC -  VCC (Voltage Controlled Computer) Atmega2560. >Elby AVR synth (AT90S8535)

2.             STM32

    Eg. 

    > Mutable Instruments

     Tides, Peaks, Streams, Yarns, Braids, Frames (STM32F103CBT6)
     Clouds, Elements 

     Clouds, Elements STM32F405RGT6

    > Owl modular - STM32F4

 

The technology being used in musical instruments gets evolved by the ages and has come from use of microprocessors , to microcontrollers and then to PICs(The name PIC initially referred to Peripheral Interface Controller), the general purpose microcontrollers. Hence, the microcontrollers and microprocessors have a vital contribution even in the musical sector.