Project P06520 - Tempo Meter
Preliminary Design Review (2/24/2006) – Pre-Read Material
Team Members: John Gifford [EE – team lead and sponsor]
Scott DVileskis [EE]
Frank Gill [ME]
Jeremy LaDuke [ISE]
I. Project Overview:
The purpose of this project is to design and construct a device for providing
real-time feedback to a drummer about the average speed, or tempo, at which
they are playing. This information is useful to drummers, because they are
typically responsible for setting and maintaining the tempo for the whole band.
This "tempo meter" device will be a significant improvement over the traditional
metronome device which tells a musician how fast to play rather than telling
them how fast they are playing. A tempo meter will allow a drummer to adjust
tempos as desired while still providing an indication of how consistent the
tempos are. There is already one tempo meter device on the market, but it only
displays the amount of time between each two consecutive trigger events, which
is too simplistic to be very useful. The intent of this project is to design a better
tempo meter, one which is capable of finding the "beat" in any rhythm in order
to calculate and display the average tempo being played. The primary target
application for this device is a marching bass drum, although it is desirable for
the device to work with various types of drums. The sponsor's goal is to produce
at least one complete working unit, with the possibility of creating a marketable
product.
II. Definition of Terms:
beat - the "pulse" of the music; when marching, each footstep is one beat;
the beats are evenly spaced at a constant rate
tempo - the rate of the beats, in Beats-Per-Minute [BPM]
impulse - one strike of the drum; one note in the music; a single trigger event;
impulses may or may not coincide with beats
rhythm - the pattern of notes or impulses; typically more complex than a
straight beat
III. Implementation:
Four operational modes:
1. Tempo Meter Mode
- This is the unit’s power-on default mode.
- Unit continuously calculates and displays the current tempo.
- The determination is based on impulse timing from drum trigger(s).
- The algorithm supports a range of 75-149BPM.
2. Metronome Mode
- The unit is just a basic metronome in this mode.
- Use UP and DOWN buttons to set the target tempo.
- Unit flashes the target tempo at the indicated rate (50% duty cycle).
- The metronome supports a range of 40-199BPM.
3. Tempo Trainer Mode
- This mode is for practice situations.
- Unit starts in metronome mode to provide desired reference tempo.
- Upon detection of first impulse, unit shifts to tempo meter mode.
- Use UP or DOWN button to stop sampling and display statistics:
overall average tempo
average deviation from reference tempo
4. Clock Set Mode
- This mode is for setting the time-of-day clock.
- Use UP button to set the hours and DOWN button to set the minutes.
Display:
1. Always display the current mode.
2. Always display the time-of-day in 12-hour format.
3. Display the appropriate tempo value or statistics for the current mode.
4. The display is a 128x64 graphic LCD, reflective type for long battery life.
Power Supply:
1. Four AA cells in series provide power to the microcontroller, the RTC,
and the LCD module via a dual-output +/-5V DC-DC converter.
2. A BR2032 3V Lithium cell provides long-term backup for the RTC.
Switches:
1. There is one push-on/push-off POWER switch.
2. There are three momentary switches for MODE, UP, and DOWN.
3. Tapping the MODE switch cycles the unit through its four modes.
Signal processing:
1. The unit has two industry-standard ¼” mono female phone jacks.
2. The input signals are low-pass filtered and passed to an ADC.
3. An algorithm in the PIC microcontroller detects and times the impulses
and then analyzes the timing of the impulses to determine the tempo.
P06520_pdr_preread.doc
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P06520_pdr_preread.doc
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