1. Auto-Chromatic Instrument Tuner Erin Smith Advisor: Dr. James Irwin Date: November 20th, 2000

2. Presentation Overview n Project Summary n Milestones & Critical Problems n Future Work

3. Project Summary n Brief Overview of Operation n State of Received Tuner n Proposed Modifications

4. Overview of Operation n The auto-chromatic tuner is a self contained tool that is used to determine the pitch and intonation of a musical instrument in real time

5. Functional Description n Inputs –Microphone –Pitch selector –Power/Mode Switch n Outputs –Pitch indicator –Digital tuning indicator –Speaker n 8031 Microcontroller

6. E b 6 Auto-Chromatic Tuner Off Auto Manua l Tuning Audible Pitch GYYRR LED Display Pitches: G: Green LED ± 5 cents Y: Yellow LED ± 5-15 cents R: Red LED ± 15-50 cents Octave Up Pitch Up Tuning Pitch Down Octave Down

7. Microprocessor Threshold Detector AmplifierMicrophone Timer/ Counter Overflow Bus Divide By 2 Tree Bus Power/ Mode Switch Mode Switched DC Power to all sub- systems Clock DC Power Pitch Selector Bus Function Generator Bus Speaker Driver Speaker Selected Pitch Out Audio In Display Control BusAnalog Meter Pitch Indicator Pitch Indicator Tuning LED’s Automatic Gain Control Frequency Look-Up Table - Parts which do not work, or have not been included yet

8. Microprocessor Threshold Detector AmplifierMicrophone Timer/ Counter Overflow Bus Divide By 2 Tree Bus Power/ Mode Switch Mode Switched DC Power to all sub- systems Clock DC Power Pitch Selector Bus Function Generator Bus Speaker Driver Speaker Selected Pitch Out Audio In Display Control BusAnalog Meter Pitch Indicator Pitch Indicator Tuning LED’s Automatic Gain Control Frequency Look-Up Table - Parts which were modified

9. Start Initialization Mode Read Mode/ Power Switch Auto Tune Manual Tune Setup and Start Counter Adjust Frequency Driver Counter Overflow Tuning Mode Yes Read Counter Display Results No Audible Reference Pitch Display Pitch

10. State of Received Tuner n Auto-tune worked with pre-selected octave only n Manual tune supposedly worked, or had some portion working n Analog and Digital Tuning worked n Display worked correctly n Pieces of software worked, but not all in one program

11. State of Received Tuner n Tuner did not work as expected when connected to power supply n Programmer was faulty, PAL’s were broken n Unit did not work until mid-March n Analog meter ceased to work (not sure if problem with hardware or software) n No software located for manual tune

12. Proposed Modifications n Manual Tune completion n Automatic Gain Control n Expand Digital Tuning n Auto-Tune Mode completion

13. Manual Tune n Software for Manual Tune could not be located n Scope was too large, given that no code was available to work from n Due to time constraints, was not able to complete Manual Tune mode

14. Automatic Gain Control n Attempted several different configurations in the Spring –Gain circuit with Varistor –Circuit with an FET

15. Varistor VinVout Gain circuit with Varitstor in parallel gnd Vin Vout Low amplitude signal Gain circuit with FET in feedback loop LPF

16. Automatic Gain Control n Found article with an AGC circuit which involves a digital potentiometer n Parts did not come in, so AGC could not be implemented

17. CONTROL + x(t) y(t) Eref E(t) _ AGC Circuit which utilizes a Digital Potentiometer

18. Digital Tuning n Wanted to expand digital tuning from 5 LED’s to 9 LED’s n Intended to take place of analog meter n Expanded the truth/logic tables n Not enough memory or bits available to implement the expansion n Required major re-design of hardware and doing the wire wrapping over again

19. Excerpts of Expansion of the Truth Tables (formerly only A15-A11 needed)

20. E b 6 Auto-Chromatic Tuner Off Auto Manua l Tuning Audible Pitch GBBYYOORR LED/LCD Display Pitches: G: Green LED ± 3 cents B: Blue LED ± 4-10 cents Y: Yellow LED ± 11-20 cents O: Orange LED ± 21-30 cents R: Red LED ± 31-50 cents Octave:Pitch: Tuning

21. Auto-Tune Mode n Worked with pre-selected octave only n Learned how Timer 0 Overflow worked in relationship to counting the period n When overflow occurred, decremented the octave and reset the divide by 2^n n Once a pitch is successfully detected, reset the divide by 2^n to the 9th octave n Device is then ready to search again

22. Milestones & Critical Problems n Critical Problems –Unit did not work initially –Not enough memory to expand LED’s –Lack of software for manual tune –Parts for AGC did not come in

23. Milestones & Critical Problems n Milestones –Getting unit up and running –Expanding tables for LED’s –Determined a good duty cycle and waveform for the Audible Reference Pitch with a function generator –Determined design for AGC circuit –Successfully implementing Auto Tune Mode

24. Future Work n Manual Tune n Audible Reference Pitch n Expanded LED Display n Packaging n Automatic Gain Control n New Hardware:microphone, speaker, CPU, and memory

25. Any Questions?