IntegTheremin

From blwiki
Jump to: navigation, search

Tindie-larges-v2.png

ITheremin-2.jpg

Features

The Integrated Theremin combines five of our boards into one. The boards included are:

  • MiniDuino
    • 16 MHz ATMega 328 processor
    • Arduino UNO Code and IDE Compatible
    • TFT Display connector
  • FTDI-USB-TTL
    • USB Interface
    • Board is not powerable from FTDI
  • HV Digital Pots
    • 10-bits, 1024 steps
    • Control Frequency and Voltage
  • AudioAmp386
    • 3/4 Watt Output
    • Standard RCA phone style connector
  • XR-2206 Voltage Controlled Oscillator
    • Waveform Adjustment pot from X3 version of XR-2206

Additional Features

The board has additional features including:

  • Advanced Power Supply Design
    • Single +12V power supply input
    • +5V High-Efficiency Switcher to drive logic and High Intensity IR Sensors
      • Previous (separate board) design had a hot regulator on the MiniDuino
        • Due to the current drop of the +12V or +9V to 5V
          • At 200 mA due to the IR sensor cards
      • Total power Measured at 12V, 130 mA =  1.6 Watts
  • Dedicated connectors for IR Sensors
  • Direct (DC) coupling for Voltage Controlled Oscillator to Audio Amplifier
    • AC cap in series with the previous design led to clipping of the audio
  • Added connection to allow Microprocessor to monitor (via A/D) the VCO level for smoother volume control transitions
    • Write all of the D/A serial bits then cycle the FSYNC line to load the D/A
    • Voltage divider
      • Average voltage into divider is 6V
      • Divider resistors 2.2K, 4.7K
      • Divider ratio is (2.2/(2.2+4.7)) = 0.31884
      • 6V * divider ratio = 1.913 V
      • 1.913V * (1023 counts/5V) =  391 counts
      • Peak voltage is 12V - scales to 3.82V which is safely below the 5V input of the A/D
    • Measurements:
      • Minimum count = 278
      • Maximum count = 414
      • Average count = 346
    • Measured the average voltage and it wasn't 6V as expected, it was 5.3V which correlates well to the 346 count
    • Where is the transition supposed to happen with respect to the waveform to write data to the pots? 
    • A/D sample rate is around 10K samples/sec
    • If the max freq is 1KHz that means that the waveform is only sampled 10 times per cycle so there could be a large step in volume
    • Start up question as well - the board needs to be autocalibrated at startup
    • May need hardware assist to cycle FSYNC at zero crossing
    • May want to connect the data and clock to the MOSI and SCK lines instead of PIO lines to speed up transfers
    • May want to use logic analyzer to debug
  • Board layout is slightly under 50 mm x 100 mm to use SeeedStudio service ($30 for 10 pcs).
  • Board has four mounting holes
  • New schematic design using hierarchical sheets
  • Split Power and ground planes (+12V/+5V) at center of card with jumper to connect GNDs

Block Diagram

IThereminBlockX1.png

Connectors

J1 - Power Connector

  1. +12V
  2. Ground

J2 -Analog Output - RCA connector

J3 -USB-B Mini

J4 - 5-Way Switch

  1. Ground
  2. Voltage (+5V)
  3. Signal (Keypad)

J5 -Volume GVVS

  1. Ground
  2. Emitter Voltage (5V @ 100 mA)
  3. Sensor Voltage
  4. Sensor Output

J6 - Frequency GVVS

  1. Ground
  2. Emitter Voltage (5V @ 100 mA)
  3. Sensor Voltage
  4. Sensor Output

J7 -Analog Spares

  1. AD5
  2. AD4
  3. AREF
  4. GND
  5. AREF
  6. VCC

J8 - TFT LCD

  1. VCC
  2. Backlight (GND)
  3. RESET
  4. RS
  5. MISO
  6. MOSI
  7. SCK
  8. LCDCS
  9. SDCS
  10. GND

J9(X2)/J10(X1) - Ground jumper

1-2 - GND to GNDA

RV1 - Waveform Adjust

Supported Peripherals

LCD screen.png

Sw5Way.png

IR-horiz-top.png

IR-vert-top.png