AV Institute · Week 2Programming & Control Basics

Lesson

Program a Room Start-up, Display On/Off, Source Selection & Volume Workflow

Est. 75 minCompetency: Express a complete room workflow as program logic and pseudocode.

Learning objectives

Write a Start sequence that powers devices in the right order.
Implement display on/off with feedback confirmation.
Implement source selection that routes video and updates the UI.
Implement volume and mute control with feedback.
Write a Shutdown sequence that leaves the room safe.

Vocabulary

Sequence: An ordered set of commands executed to reach a room state.
Source selection: Choosing which input feeds the display (and which audio path).
Ramp: A gradually changing value, e.g. volume rising over time.
Interlock: Logic where selecting one source deselects the others.

Lesson content

Now combine everything into the room's core workflows: Start, power, source, volume, and Shutdown. Written as pseudocode, these become the specification you later implement in any ecosystem.

Start sequence

event: button "Start" pressed
  if roomState != STANDBY: return        // ignore if already starting
  roomState = STARTING
  send display power ON
  send switcher route SOURCE_LAPTOP -> OUTPUT_DISPLAY
  send dsp unmute program
  volume = 50; mute = false
  // confirm from feedback, then:
  roomState = ON

Display on/off with feedback

event: button "Display Power" pressed
  if displayPower == OFF:
    send display "PON"; displayPower = PENDING_ON
  else:
    send display "POF"; displayPower = PENDING_OFF

event: feedback display power state
  displayPower = receivedState
  update UI button state = receivedState
  if displayPower == ON and roomState == STARTING:
    roomState = ON

Source selection (interlock)

event: button "Laptop" pressed
  currentSource = LAPTOP
  send switcher route LAPTOP -> DISPLAY
  send dsp route LAPTOP_AUDIO -> PROGRAM
  update UI: highlight Laptop, dim others   // interlock

event: button "Codec" pressed
  currentSource = CODEC
  send switcher route CODEC -> DISPLAY
  send dsp route CODEC_AUDIO -> PROGRAM
  update UI: highlight Codec, dim others

Volume and mute

event: volume slider moved to v
  volume = v; mute = false
  send dsp set program level = v
  update UI slider = v

event: button "Mute" pressed
  mute = !mute
  send dsp mute program = mute
  update UI mute button state = mute

Shutdown sequence

event: button "Shutdown" pressed
  if roomState != ON: return
  roomState = SHUTTING_DOWN
  send dsp mute program
  send display power OFF
  currentSource = NONE
  // after display confirms off:
  roomState = STANDBY
  update UI to welcome/standby screen

Order matters

Power the display first and let it settle before routing. Mute audio before un-routing to avoid pops. Always end Shutdown with the room in a known standby state so the next Start is clean.

Worked example

Full room flow: press Start → display powers on, laptop is routed, audio unmutes at 50. Press Codec → source switches, audio follows. Adjust volume slider → level changes, UI reflects the real value. Press Shutdown → audio mutes, display powers off, room returns to standby. Every step is confirmed from device feedback.

Implementation checklist

✓Start sequence powers devices in the right order with confirmation.
✓Display on/off updates the UI from real feedback.
✓Source selection interlocks: only one highlighted at a time.
✓Volume and mute update from DSP feedback.
✓Shutdown leaves the room in a safe standby state.

Downloadable study guide

study-guide.txtcopy-paste ready

01. Start: set state, power display, route source, unmute at 50, confirm, set ON.
02. Display on/off: send command, set pending, confirm from feedback, update UI.
03. Source selection = interlock; only one source highlighted.
04. Volume/mute: update variable, send level, reflect real feedback.
05. Shutdown: mute, power off, clear source, return to STANDBY.