Revision as of 19:52, 11 November 2024

Press #1 For:

Description

From getting your BSN to installing internet in your new home to renting a car, rigid mazes of bureaucratic systems hold us all hostage. In the spirit of collective catharsis 'Press One For' invites you to share and listen to stories of how these systems frustrated you, or how you frustrated them.

T65 Rotary Phone bought by Sevgi n' Fred

Cookbook

Parts Required

USB interface to 3.5mm

https://www.adafruit.com/product/1475

3.5mm Cables

Old phone (T65)

https://www.marktplaats.nl/v/telecommunicatie/vaste-telefoons-niet-draadloos/m2158407457-ptt-t65-goed-werkende-nostalgische-telefoon

Raspberry Pi

TRS 3.5 Jack x2

Loads of wires

old headphones with a mic (apple earpod works best)

Things we done

- We got one phone from ScrapXL Rotterdam and one from Marktplaats. The first one was a T65

[11 (Neg), 12(Pos) speaker output]

We

- We took the phone apart and got the speaker to work by connecting the blue and red cables from the phone out to the audio jack to the soundcard to the computer. played show me the body, was good.

- Then we tried the microphone but its a carbon mic and it didnt work. so we atttached a battery and hoped. didnt work.

- We took apart wired headphones that had mic in them to see if we could use the mic from it rather than the carbon mic in the telephone.-> didnt work, headphone cable is TRRS not TRS:

spent a day trying to wire up TRRS to an audio cable, turns out the audio jack was the wrong kind.

then wired it directly to a TRS jack, worked!!!!!!!!!!!!!

then cable managed, looks beautiful now. now we have working speakers and working mic.

This is how you could make it work too (Schema 1)

From the headphones you need to...

Connect th Blue (Ground) to the Sleeve of the TRS jack

Connect the Red (mic) to Pin (Ring) 1 or 2 of the TRS jack

MAKE SURE THE HEADPHONES CONNECTION IS CLOSED!

The wiring used

sketch of the wiring of the handset connection (Schema 1)

Next Steps:

We need to work out how to read the keypad input on the raspberrypi. Mark Powers has a snippet of code that supposedly works with this: https://marks.kitchen/blog/rotary_phone_running_linux/

To test our phone we used this GitHub project: https://github.com/ralphcrutzen/PTT-Tafeltjes-Telefoon?tab=readme-ov-file. > This project turns the phone into a math game where a child asks you a times table question and you are supposed to give the correct answer using the rotary keypad. When you dial the answer the py code reads it as 2 separate entires and gives you a Goed zo! if you gave the correct answer.

Fred is translating the code to eng. He also thinks I can't do times tables.

Set up the raspberrypi, named it telephone.(tut here:https://nematicslab.com/how-to-enable-ssh-without-using-a-monitor/)

Fred made me a user(Sevgi) as well and we tested the connections first, adjusted the code accordingly. Fred tested the connections like this (this is the final working version):

import RPi.GPIO as GPIO


GPIO.setmode(GPIO.BCM)
GPIO.setup(23, GPIO.IN, pull_up_down = GPIO.PUD_UP)
GPIO.setup(24, GPIO.IN, pull_up_down = GPIO.PUD_UP)
GPIO.setup(25, GPIO.IN, pull_up_down = GPIO.PUD_UP)

while True:
        
        print('-')
        if GPIO.input(23):
                print('23')
        if GPIO.input(25):
                print('25')
        if GPIO.input(24):
                print('24')

Here is how we set up the wires and the raspberry pi:

This wiring worked for us at first, but then we had to put the ground cables in different Rbpi GND's for it to work again.

Here is the eng version of the dutch code: https://pzwiki.wdka.nl/mediadesign/User:Wordfa/oldphonehack/PTT_Tafeltjes_Telefoon

We now reverted back to writing the code Ralph Crutzen's way, using pygame. We pulled this code from: https://github.com/pygame/pygame/blob/main/examples/audiocapture.py

""" pygame.examples.audiocapture

A pygame 2 experiment.

* record sound from a microphone
* play back the recorded sound
"""
import pygame as pg
import time
import wave

from pygame._sdl2 import (
    get_audio_device_names,
    AudioDevice,
    AUDIO_F32,
    AUDIO_ALLOW_FORMAT_CHANGE,
)
from pygame._sdl2.mixer import set_post_mix

# sound length (seconds, a float)
SOUNDLEN = 2.0
# sound frequency (in Herz: the number of vibrations per second)
SOUNDFREQ = 1000

# maximal amplitude
MAXAMP = 32767 / 2
# sampling frequency (in Herz: the number of samples per second)
SAMPLINGFREQ = 44100
# the number of channels (1=mono, 2=stereo)
NCHANNELS = 2

pg.mixer.pre_init(44100, 32, 2, 512)
pg.init()

# init_subsystem(INIT_AUDIO)
names = get_audio_device_names(True)
print(names)
sounds = []
sound_chunks = []


def callback(audiodevice, audiomemoryview):
    """This is called in the sound thread.

    Note, that the frequency and such you request may not be what you get.
    """
    # print(type(audiomemoryview), len(audiomemoryview))
    # print(audiodevice)
    sound_chunks.append(bytes(audiomemoryview))


def postmix_callback(postmix, audiomemoryview):
    """This is called in the sound thread.

    At the end of mixing we get this data.
    """
    print(type(audiomemoryview), len(audiomemoryview))
    print(postmix)


set_post_mix(postmix_callback)

audio = AudioDevice(
    devicename=names[0],
    iscapture=True,
    frequency=44100,
    audioformat=AUDIO_F32,
    numchannels=2,
    chunksize=512,
    allowed_changes=AUDIO_ALLOW_FORMAT_CHANGE,
    callback=callback,
)
# start recording.
audio.pause(0)
print(audio)

print(f"recording with '{names[0]}'")
time.sleep(2)


print("Turning data into a pg.mixer.Sound")

sound = pg.mixer.Sound(buffer=b"".join(sound_chunks))
snd = pg.mixer.Sound(sound)

# open new wave file
sfile = wave.open('pure_tone.wav', 'w')

# set the parameters
sfile.setnchannels(NCHANNELS)

# write raw PyGame sound buffer to wave file
sfile.writeframesraw(snd.get_raw())

# close file
sfile.close()

print("playing back recorded sound")
sound.play()
time.sleep(2)
pg.quit()

This didn't really work, just worked for us to record the sound and play it back on the handset.

We gave up on pygame and used instead.

#!/usr/bin/env python3
"""Create a recording with arbitrary duration.

The soundfile module (https://python-soundfile.readthedocs.io/)
has to be installed!

"""
import argparse
import tempfile
import queue
import sys

import sounddevice as sd
import soundfile as sf
import numpy  # Make sure NumPy is loaded before it is used in the callback
assert numpy  # avoid "imported but unused" message (W0611)


def int_or_str(text):
    """Helper function for argument parsing."""
    try:
        return int(text)
    except ValueError:
        return text


parser = argparse.ArgumentParser(add_help=False)
parser.add_argument(
    '-l', '--list-devices', action='store_true',
    help='show list of audio devices and exit')
args, remaining = parser.parse_known_args()
if args.list_devices:
    print(sd.query_devices())
    parser.exit(0)
parser = argparse.ArgumentParser(
    description=__doc__,
    formatter_class=argparse.RawDescriptionHelpFormatter,
    parents=[parser])
parser.add_argument(
    'filename', nargs='?', metavar='FILENAME',
    help='audio file to store recording to')
parser.add_argument(
    '-d', '--device', type=int_or_str,
    help='input device (numeric ID or substring)')
parser.add_argument(
    '-r', '--samplerate', type=int, help='sampling rate')
parser.add_argument(
    '-c', '--channels', type=int, default=1, help='number of input channels')
parser.add_argument(
    '-t', '--subtype', type=str, help='sound file subtype (e.g. "PCM_24")')
args = parser.parse_args(remaining)

q = queue.Queue()


def callback(indata, frames, time, status):
    """This is called (from a separate thread) for each audio block."""