Our parents’ first mobile phone, probably.
Background
These phones are cheap on eBay and elsewhere, and so are simple GSM/Bluetooth radio modules.
What it does
Makes and receives calls either by itself or as a Bluetooth extension to your existing mobile phone.
What it’s made of
Look for the MicroTAC models with the dot-matrix display – they’re way cooler.
Here are the models I have:
Theory of operation
Resources
- https://www.adafruit.com/product/1946
- http://mobile4dev.blogspot.com/2016/07/sda5714-led-display-working-with.html?m=1
- http://www.picaxe.com/RTTTL-Ringtones-for-Tune-Command/
- https://forum.arduino.cc/index.php?topic=53358.0
- https://forum.arduino.cc/index.php?topic=225485.0
- https://github.com/cefn/non-blocking-rtttl-arduino
- https://adamonsoon.github.io/rtttl-play/
- https://codepen.io/mog13/pen/WYRJQJ
- https://www.pocket-lint.com/phones/news/131502-best-and-worst-nokia-phones-ever
- https://hackaday.com/2017/01/16/shmoocon-2017-dig-out-your-old-brick-phone/
- https://www.rtl-sdr.com/tag/amps/
- https://github.com/PetteriAimonen/esp-walkie-talkie
- http://iot-bits.com/interfacing-audio-codec-esp32/
- https://github.com/IoTBits/ESP32_SGTL5000_driver
- https://github.com/torvalds/linux/blob/master/sound/soc/codecs/wm8960.c
- https://github.com/TaraHoleInIt/tarablessd1306
- https://www.makerfabs.com/esp32-a1s-wifi-bt-soc-audio-module.html