The Problems of a Guitarist
• Tuning mechanism hasn’t evolved much.
• Each peg is still turned manually to get the right tone.
• Factors like heat change the tone of strings.
• Stretched strings are very tough to keep in tone.
• People rely on software like Guitar Tuner Pro.
• Lot of time gets wasted.
MCK – Master Control Knob
• adjusts volume – normal function
• on pull – becomes tuning selector
• LEDs show status of tuning
• shows battery level (1-10)
• 2.4 V NiCd battery pack
• Stepped up to 12V to power other parts (motors etc)
• 90 minutes full charge
•200 tunings per full charge
Powerhead Locking Tuners
• Rohm's BA6845FS motor drivers
• Rotates to pull strings for tuning
• RPM is reduced by ratio of 500:1
• also works for manual tuning
• detects frequencies
• feeds signals to Data Transmitting Tailpiece
• the signals are multiplexed into C8051F120 MCU’s
Data Transmitting Tailpiece
• contains Silicon Labs C8051F120 12-bit MicroController
• uses crystal-derived reference frequency, to decide if string’s
frequency is flat, sharp or on pitch.
• depending on the string’s frequency, controls the motors in
#1 Master Control Knob is pulled up
• this enables the C8051F120 unit
• lets user load a preset
#2 Pickup detects frequencies
• converts string vibrations into frequencies
• multiplexes all 6 string frequencies
• feeds them to C8051F120 ‘s input
#3 Tailpiece (MCU) analysis
• C8051F120 MCU analyses the signals from pickup
• decides which string to tune
• decides how much to tune on the basis of
• preset loaded
• sends signals to Rohm's BA6845FS motor drivers
#4 String Tuning
• Rohm's BA6845FS motor driver controls the tiny servo
motors attached to each string
• Each string is rotated unless it reaches desired frequency
• Make sure no two strings touch each other – might lead to short
• Make sure MCK is not pulled when while guitar is in storage, this
would drain out the battery completely
• While strings are removed, make sure that Tailpiece (MCU)
doesn’t move, this could damage its connectors
• Don’t turn the pegs manually while MCK is pulled, i.e. Robot is
• We saw, how a microcontroller helps in automating difficult
• A microcontroller makes redundant tasks easier.
• Gibson Guitar Robot is able to take intelligent decisions by help
of a microcontroller.
• A microcontroller adds more functionalities and values to a
For more information -
• C8051F120 Datasheet