announcement-box/README.md

# Announcement Box

Linux box with a loudspeaker and an emergency light to be used for announcements and notifications.

## Hardware
### Overview
 * SBC with GPIOs and sound output :: OrangePi Zero with an expansion board
 * PA system
   * speaker :: 30W, 4 Ohms horn loudspeaker
   * sound amplifier :: mono 18W sound amplifier
   * relay module :: 12V low trigger relay
 * Warning Light system
   * warning light :: 12V 10W rotary orange warning light
   * relay module :: 12V low trigger relay
 * System Activity Light system
   * indicator LED
 * Human Activity Sensor system
   * PIR module

### Building
TBD

## Software
### Overview
 * Operating System - Linux :: Armbian Bullseye for the OrangePi Zero
 * PA System
   * Voice Synthesizer :: Festival / ESpeak

### Installation
Run as root:
```bash
cp toolkit/* /usr/local/bin/

cp etc/systemd/system /etc/systemd/system
systemctl enable --now system-activity-light.service 
systemctl enable --now human-activity-sensor.service
```

## Implementation Notes

### Armbian + OrangePi Zero Installation

#### Enable analog soundcard
```
sudo armbian-config
# System > Hardware > [*] analog-codec
```

#### Software Dependencies
##### OS Packages
```bash
apt install mplayer espeak-ng
```

##### GPIO toolkit
```bash
# upstream:
#git clone https://github.com/orangepi-xunlong/wiringOP
# enhanced:
git clone https://github.com/Dejvino/wiringOP
cd wiringOP
./build clean
./build
```

### PA System
#### Enabling mixed sound output
```bash
cat ~/.asoundrc
pcm.!default plug:dmix
```

#### Text to Speech
```bash
## Festival
# reading
...
# to file
text2wave text.txt > wave.wav

## ESpeak
# voices:
ls /usr/lib/arm-linux-gnueabihf/espeak-data/voices/
# reading
espeak -f text.txt -p 40 -s 160 -v "en-us"
# to file
espeak -f text.txt -p 40 -s 160 -k15 -g 1 -w wave.wav
# using SSML (e.g.: https://www.xml.com/pub/a/2004/10/20/ssml.html)
espeak -f ssml.txt -m
```

#### Converting into a low-quality broadcast audio
```bash
sox infile.wav outfile.wav downsample echo 0.5 1 1 1
```

### Human Activity Sensor

#### Reading File Timestamp
```bash
stat /var/tmp/human_last_seen --format=%Y
```