I believe in a society like today, we need to have better control over our communications. Today’s smartphones have been accused of being devices of mass surveillance. Therefore I have decided to build my own cellphone. I found this guide on the internetz, which describes an open-source cellphone platform based on a GSM module and an AVR microcontroller. I selected it as a starting point for my cellphone. It will most certainly receive software updates from me (I want snake!), and probably even hardware updates in the future. Yes, I know, GSM is not secure at all, and it is vulnerable to man-in-the-middle attacks, but I still prefer the man-in-the-middle over nsa-over-the-internetz.
Enough jabber, for now, let’s get to the fun part! So far, I have received all the needed components from the Bill of Materials (BOM) for the phone’s LCD version, besides the PAS414HR-VA5R SuperCap, which has been discontinued. Since the proposed replacement part isn’t good enough, I managed to find some leftover PAS414HR-VG1 at Farnell and instead ordered a few of those. It will take some scratching and soldering to fit it on the PCB, but its values are correct. Since I am living in Sweden, I had to find alternative suppliers for my materials (Electrokit for some electronics, In-Time for the antennas, Farnell for the SuperCaps). Some had to be ordered from DigiKey anyway. Try to keep your parts ordered from DigiKey below your country’s import tax threshold. Otherwise, you might end up paying import taxes like me, which is not fun.
Here is a picture of the PCBs from OSH Park, which are of excellent quality. More will come once I receive the SuperCaps and start soldering the cellphone.