Raspberry Pi in a Rotary Dial Phone

======================================== The first intention for this project was to put skype on the raspberry pi and use this as a skype voice call client. Considering how downloading the skypekit is no longer available this quickly changed.

Now this project will allow the user to dial a number on the phone and using the raspberry pi the phone will read back some information like

• Time
• Date
• Temperature inside or outside(dual DS18B20 sensor)
• A random compliment
• Latest news headlines
• weather for the day
• anything else I can think of

So what is inside and how does it work

At present there is the raspberry pi, the phone and two DS18B20 temperature sensors.

Temperature Sensors

These are two DS18B20 sensors connected with 1-wire to GPIO 4 using a single 4.7k pullup resistor to 3.3V. Both sensors are powered from 3.3V and are not configured in parasite mode.
To get them working on the pi by loading them manually I used

    modprobe w1-gpio
    modprobe w1-therm

and to load them automatically add these lines to /etc/modules

    w1-gpio
    w1-therm

To read the sensor you just use this, where 28-00xxxxxxx is your device.

    cat /sys/bus/w1/devices/28-000035432/w1-slave

Rotary Dial

This is a fairly basic device. I found a sweet library written by markfickett here for the arduino. I used it to confirm mine operated the same and quickly realised that my phone goes 0,1,2...9 not 1,2,3...9,0. So this is a trap for young players.
Connection is as follows;
The common goes to ground, both contacts are connected to 3.3V through some pull up resistors. The contacts are then connected to your input pins.

Handset

This has a speaker at the ear end and this is connected to the 3.5mm audio jack on the raspberry pi.

Speech

I decided, after reading and testing this that I should use the Google Text to speech and espeak as a backup for no internet connection. There is a good guide there how to get this working. I still have some troubles with poping and cracking when the speaking starts and stops but this will be investigated soon.

Other ideas and changes

• Use a wifi dongle as then the phone will only need power connection.
• Use a power over ethernet breakout for the same reason as above.
• Get skype or another free commonly used internet calling program working.
• Use a larger phone with the ringer for an alarm clock
• Setup the usb microphone so that a message can be recorded and played back later, or sent to someone as mp3 or text with speech to text decoding.
• Add a ringer.