Audio Guestbook

WIP, but seems to be usable

Context

Some good friends are leaving the area and we wanted to give them a gift, an audio guest book.
As we're french, we decided to use the famous old rotary phone made by Socotel, the S63.

Must have features are :

• Be able to use the rotary dialer to execute some actions
• Be able to leave an audio message
• Be able to use mic and speaker from the main phone as well as the secondary speaker
• Be able to make it ring as it used to (Spoiler : I didn't managed to make original bell work ... But I suggest another way to perform it)
• Use a rgb led to provide a status to users
• Send voice messages to a telegram channel

Here are some credits I'd like to give because the authors inspired me :

• https://www.hackster.io/carolinebuttet/turn-a-rotary-phone-into-a-radio-and-travel-through-time-14fd79
• https://github.com/ThomasChappe/S63_Arduino
• https://github.com/revolunet/s63/

Unboxing and understanding what's inside the S63

Here it is !

The rotary dialer

The rotary dialer is composed of 2 dry contacts related to :

• Is the rotary in use ? (blue and blue/while wires)
• Pulses counter linked to the dialed number (red and red/white wires)

Mic and speakers

I found the speaker quality good enough to listen to messages while I found the quality of the microphone very poor.
I decided to change the micro by one from an old unsed headset I had somewhere ;)

Phone line

This part is absolutely not necessary. I'll maybe just use wires to power the raspberry pi.

Setup

Hardware

Item	Photo	Description
Socotel S63 Phone		The phone !!(bought on le bon coin)
Raspberry pi 2 W
USB sound card		To connect mic and speaker from the main phone
Jack 3,5mm adapter		To connect the secondary speaker
USB hub		To connect soundcard and ringtone
USB extender		To connect soundcard and ringtone
USB speaker for the ringtone		Speaker used to play ringtone

OS

I simply used rpi-imager and image Raspberry pi OS LITE 64 bits.

Options set (Ctrl+Shift+X) :

• username as guestbook
• wifi settings

Packages

System

sudo apt update
sudo apt install git python3-yaml python3-pip python3-python-telegram-bot ffmpeg python3-flask
sudo apt remove python3-rpi.gpio
sudo apt install python3-rpi-lgpio
sudo pip3 install --break-system-packages gTTS gTTS-token

Led status option

There is an option to use a led (type ws2128b) to provide the guest book status.
It's executed over a dedicated daemon because it requires root elevation to access ws2128b led.
It publishes a mini API that will be able to control the LED.

In config.yml, you can set options for that led

led:
  enabled: True
  pin: 21  # GPIO pin connected to the LED
  num_leds: 1  # Number of LEDs
  brightness: 127  # Brightness of the LED

Please, choose a GPIO PWM for the led.

• Systemd unit

sudo cp contrib/led-controller.service /etc/systemd/system/
sudo chmod 644 /etc/systemd/system/led-controller.service 
sudo systemctl daemon-reload
sudo systemctl enable led-controller.service
sudo systemctl start led-controller.service

• Testing it

curl -X POST -H "Content-Type: application/json" -d '{"color": [255, 0, 0], "blinking": false}' http://localhost:5000/led # red
curl -X POST -H "Content-Type: application/json" -d '{"color": [255, 0, 0], "blinking": true}' http://localhost:5000/led # red blinking
curl -X POST -H "Content-Type: application/json" -d '{"color": [0, 0, 255], "blinking": true}' http://localhost:5000/led # blue blinking
curl -X POST -H "Content-Type: application/json" -d '{"color": [0, 0, 0], "blinking": false}' http://localhost:5000/led # Switched off

• Color codes

Color	Description
Orange solid	System is booting
Orange blinking	System is UP but audio guestbook is not launched
Green solid	Audio guestbook is launched, you can pick up the phone
Green blinking	Hooked up, waiting for a dialed number
Blue solid	Action is finished, ready to execute another one or to hang up
Blue blinking	Action is executing

Ringtone

You can enable the ringtone option that will allow you to make the phone ring.
It can be executed by calling a endpoint of the API or through a telegram message.

In config.yml, you can set options for the ringtone

ringtone:
  enabled: True
  device_address: 'hw:0,0' 
  volume: 0.1
  sound_file: 'sounds/original_bell.wav'

• Testing it

Through API

curl -X POST -H "Content-Type: application/json" http://localhost:5001/ring # Play ringtone
curl -X POST -H "Content-Type: application/json" http://localhost:5001/stop_ring # Stop ringtone

Through telegram

Audio guestbook itself

Note that most of that code has been written by chatpgt.
There might be some errors, improvements to do and so on.
Of course, you can suggest PR to help the project !

git clone https://github.com/mmourcia/audio-guestbook.git
cd audio-guestbook

Systemd unit to launch the program at start

sudo cp contrib/audio-guestbook.service /etc/systemd/system/
sudo chmod 644 /etc/systemd/system/audio-guestbook.service 
sudo systemctl daemon-reload
sudo systemctl enable audio-guestbook.service
sudo systemctl start audio-guestbook.service

Wiring

On hook contact

The S63 is equipped with a mechanical system which opens or closes a dry contact depending on whether the handset is lifted or hung up.
With a multimeter, I saw that it was a normally closed contact. It means that the circuit is closed when the headset is hung up.

As you can see, I sawed off a large part of the motherboard.

I just wanted to keep the dry contact

Pin	Endpoint	Description
GPIO22	Hook 1	On hook contact
GND	Hook 2

Rotary dialer

The rotary dialer is a piece of genius.

A first contact can tell us the rotary dialer is being used. Wires blue and blue/white are used.
A second one will make a pulse at each step during the rotation. Wires red and red/white are used.

Pin	Endpoint	Description
GPIO23	Red	Pulse counter
GND	Red/White
GPIO18	Blue	Rotary enable
??	Blue/White	I was not obliged to wire it. Who knows ?

Mic and speakers

Mic

The microphone comes from an old headset. I just soldered both wires and glued the mic with hot glue.

Main speakers

I have let the speaker as it was.

Secondary speaker

I have let the speaker as it was.

Solders on the sound card side

From the sound card side :

• I directly soldered mic and speakers wires on external terminals of jacks connectors
• I used a jack/screw adapter to connect the secondary speaker

Test it

First, adjust settings in config.yaml file

rotary:
  enable_pin: 18 # rotary in use pin
  count_pin: 23 # pulse counter pin
  bounce_time: 10
  debounce_delay: 0.01

hook:
  pin: 22 # headset hook pin
  sound_file: 'sounds/on_hook.mp3'

sounds:
  greeting: 'sounds/greeting.wav'
  leave_message: 'sounds/leave_a_message.wav'

audio_output:
  device_address: 'hw:0,0'  # Change this to your desired audio output device address. curl -X GET http://localhost:5001/audio_devices|jq . 

recording:
  max_duration: 10  # Maximum duration in seconds

telegram:
  token: "YOUR_TELEGRAM_BOT_TOKEN" # if set, the program will send recorded voice to telegram. (set it to "" to disable telegram).
  chat_id: "YOUR_TELEGRAM_CHAT_ID"

led:
  enabled: True
  pin: 21  # GPIO pin connected to the LED
  num_leds: 1  # Number of LEDs
  brightness: 127  # Brightness of the LED

ringtone:
  enabled: True
  device_address: 'hw:1,0' # Change this to your desired audio output device address. curl -X GET http://localhost:5001/audio_devices|jq . 
  volume: 0.1
  sound_file: 'sounds/original_bell.wav'

Execute the guestbook from the command line :

python3 main.py

Debug messages will appear on the tty.

Or using systemd

sudo systemctl start audio-guestbook.service

To get logs, use the following command :

sudo journalctl -fu audio-guestbook.service

Now you can try

• to pick up the headset, you'll listen to the original dial frequency
• to dial 1, you'll listen to a recorded message
• to dial 2, you'll be able to record a message (10s max)
• to dial 3, you'll listen to the last recorded message
• to dial 4, you'll listen to a random french joke taken from blagues-api.fr

To update or add new actions, have a look at dialed_number directory.

Enjoy !

Troubleshooting

Audio devices

To help you finding your audio devices, you can use a special route of the API to get it

curl -s -X GET http://localhost:5001/audio_devices|jq .
{
  "audio_devices": [
    {
      "device_address": "hw:0,0",
      "name": "UACDemoV10 [UACDemoV1.0]: USB Audio"
    },
    {
      "device_address": "hw:1,0",
      "name": "Device [USB PnP Sound Device]: USB Audio"
    },
    {
      "device_address": "hw:2,0",
      "name": "vc4hdmi [vc4-hdmi]: MAI PCM i2s-hifi-0"
    }
  ]
}

Set capture volume

First get the name of the mixer

amixer

And then set the volume capture

amixer sset 'Mic' 90%

Get logs

sudo journalctl -fu audio-guestbook.service
sudo journalctl -fu led-controller.service