ultra: ultrasonic speaker

Description

Uses an Arduino Uno, electronic components and a finite state machine (FSM) to create a multimodal ultrasonic speaker.

Microcontroller

Currently uses an Arduino Uno powered by a 1000mAH battery, USB switch and USB cable. A perma-proto board attached to the Uno contains:

• (2) push buttons, UP (Uno 2) and Enter (Uno 4), UP cycles thru states, ENTER enters state
• (3) LEDs with current limiting resistors, Bit0 (Uno 3), Bit1 (Uno 5) and Blue (Uno 6). Bit0/1 indicate state and Blue indicates the indicates the speaker is being driven, and shows by way of intensity, State1 dim, audible frequencies, State2 medium, low ultrasonic random frequencies for a random time and State3 bright, constant 28KHz.
• (1) low power audio speaker
• tbd audio amplifier circuit, not yet implemented

Overview

Uses a 4-state FSM to determine which routine to run. The two buttons cycle through the FSM (up or down) and each state drives a particular routine:

• State 0: Null state
• State 1: Audible state, frequencies from for a random time
• State 2: Low Ultrasonic frequencies from for a random time
• State 3: Constant ultrasonic frequency of 28KHz

Software

clocks

• clocks - provides all clocks required for ultra, used instead of sysclock

• The three Timer/Counters are used in the following manner:

• T/C 0 - drives BLUE LED, indicates sound (audible/ultra 1/ultra 2)

• T/C 1 - drives speaker sound (audible/ultra 1/ultra 2)

• T/C 2 - is a 1 millisecond timer, millis() and a debounce clock

• sound()

  • Uses T/C 1 to drive speaker sound (audible/ultra 1/ultra 2)
  • Speaker, Audible and ultrasonic Audio
  • frequency based on (freq)
  • PWM_freq = 16000000 / (2 * prescalar * OCR1A) DSpage 137
  • OC1A toggles at PWM_freq, effectively a divide by 2
  • speaker freq = 16x10^6 / (2 * 1 * OCR1A * 2)
  • Example frequencies: OCR1A = 4x10^6/frequency or 4000/(freq in kHz)
  • 5kHz = 800 (or 4000/5)
  • 10kHz = 400
  • 20kHz = 200
  • 28kHz = 143

main Finite State Machine Lock - uses a FSM to cycle through 4 states

• Requires 3 LEDs/resistors to be connected to pins 3/5/6
• Requires 2 push buttons to be connected to pins 2/4 INPUT_PULLUP Mode
• UP increments through states
• ENTER enters the state:

state0 Null state, does nothing, provides capability to boot into "safe" state

state1 Audible state, random audible freq for random time

state2 Ultrasonic state, random audible freq for random time

state3 Ultrasonic state, fixed 28KHz freq