Audio Trigger / Detector

This device listens for an audio signal at the RCA input and in response turns the audio equipment on using IR remote code or a relay. It als turns the audio equipment off when there was no audio signal detected for longer than 10min

Initial Setup

Installation

• Connect the RCA splitter to the RCA socket of the device.
• Connect one end of the 3.5mm jack cable to the device and the other one to the audio amplifier IR input.
• Connect mini-usb power cable

Use

When powered, system indicates if any pre-recorded IR codes were found by blinking slowly every 2 seconds. If not, the fast blinkng indicates that you need to set-up the device. You need to press and hold the button.

It will initiate 2-stage recording, first AUDIO START code and AUDIO STOP code. System indicates the recording status with a LED: slow blinking for the 1-st stage and fast blinking for the 2-nd.

Setting up device sensitivity is simple - done by pressing the device button once while playing audio. The device will listen to the audio signal for a short while and set the sensitivity to the given audio volume.

Status Leds

• fast blinking after startup - device was not configured yet, hold button to record IR codes and press button once to record trigger audio volume

• slow blinking after startup - everything is ok, device waits for the audio signal

• led stays on - audio detected

• fast blinking after button hold - device waits for your first infrared remote signal

• slower blinking after button hold - device waits for your second infrared remote signal

• fast blinking after button press - device learns the volume level for which it should trigger

Arduino

The board used is the Arduino Nano and the libraries:

• arduino-fsm stellarshenson fork - State Machine was implemented with arduino_fsm state machine library https://github.com/jonblack/arduino-fsm. This project however uses my fork of the library to allow timed transitions reset: https://github.com/stellarshenson/arduino-fsm. Pull was already requested from the arduino-fsm owner, hopefully my fork will be merged soon
• IRRemote v2.6.1 - IR code recording and sending was implemented with library https://github.com/z3t0/Arduino-IRremote
• JLed v4.11 - non-blocking led library used for various blinking patterns
• EnableInterrupt v1.1.0 - simple interrupt driver
• Smoothed 1.2.0 - moving average for signal detection (detecting averaged value)

State Machine

Diagram was generated by http://asciiflow.com/. System defines 4 states:

• state_audio_sense - the default state, device listens for an audio signal

• state_ircode_record - active after holding the button, records remote control codes

• state_audio_start - active when audio was detected, starts the audio system and moves to state_audio_enabled

• state_audio_enabled - active when audio is enabled

    			+---------------------+
    			| state_ircode_record |
    			+---------+--------+--+
    					  ^        |
    TRIGGER_IRCODE_RECORD |        | TRIGGER_IRCODE_RECORDED
    					  |        v
    			+---------+--------+--+
    			| state_audio_sense   +----------------------+
    			+-------------+-------+                      |
    						  ^                              |
       TRIGGER_AUDIO_DISABLED |         TRIGGER_AUDIO_SENSED |
    						  |                              v
    			+-------------+-------+             +--------+-----------+
    			| state_audio_enabled +<-----+------+ state_audio_start  |
    			+---------------------+      |      +--------------------+
    										 +
    									TRIGGER_AUDIO_ENABLED
  

Circuit and PCB

Below are the electronics circuit diagram and the board files (600dpi PNG images) for the PCB fabrication