Hi! I'm Arsenijs, a free smartphone enthusiast, and I (with help of many other people) am working on the ZeroPhone - a cheap Linux phone that you can assemble independently. It's based on a Raspberry Pi Zero (can be replaced with other CPUs), has a 2G modem (can be replaced by 3G), a small OLED screen (1.3", 128x64) and a keypad consisting of physical buttons. My goal is to make it into a phone that can actually be used in day-to-day life, and that's a goal I keep in mind while developing; I've been working on it for a year now and I finally feel like it's finally starting to take shape of a user-friendly phone - soon I'm starting a crowdfunded manufacturing run, so that more people can have one.



One of the most important aspects of ZeroPhone is the "hardware hacking" aspect. It has a full-sized USB port, extension ports with various interfaces (GPIO, SPI, I2C, SDIO and I2S) available, as well as all the schematics and board files published. So, you can connect various hardware addons to a ZeroPhone - right now, I have a VEML6070 (UV level) sensor attached to it and collecting data, but I've developed a range of addons that will be available (i.e. Ethernet, RF transceivers, SPI chip flasher, IR receiver/transmitter and so on). Also, it has three free interfaces that can be used for displays: SPI, HDMI and analog TV, which you can use to connect a bigger display if you want (in fact, with HDMI and USB, you can use it as sort of a desktop). Basically, you can hack this phone, mod it ans extend it to your heart's content

In general, you could even call ZeroPhone "modular" - even though modules are soldered to the ZeroPhone boards, they're replaceable. For example, you can replace a charging&protection module (that has the microUSB socket) with one that also has a USB-UART on it and makes the Raspberry Pi debug UART accessible, or replace the 5V step-up (powering the full-sized USB port) with one that can give more current. Or, as I've already mentioned, replace the 2G modem with a 3G modem - as I'm designing a drop-in replacement board Last but not least, you can replace the battery - the 18650 batteries are the ultimate solution, they last a long, are safe, replaceable and easy to source, but you can also have a flat LiIon battery instead, making the phone thinner (which is a requirement for some people, so I have to keep this in mind).

It's evidently limited in terms of UI - you can't really launch most popular UIs on the screen this small, so we have our own UI framework (written in Python). However, what it does really well is run Linux software - I've been using a ZeroPhone for a long time myself, and it works great in the role of a "pocket Linux computer" - mostly in the "SSH into it way", but also running all kinds of services that I want to carry with me.

It still runs Debian (specifically, Raspbian), so, say, reconfiguring a ZeroPhone to use its WiFi card as an access point is the same as configuring a Raspberry Pi to do it - it benefits from all the guides and tutorials written for Raspberry Pi. Also, I can still run something like MPD, Mopidy or MOC for music playing, and only develop a small "music player" app that controls it (for the ZeroPhone UI). Granted, it still has a stock kernel (likely not optimised for lower power consumption) and the default ext4 filesystem (so, not *completely* safe from power failures), but that's something that can easily be solved with a custom distro if necessary.

Last but not least, everything I can open-source is open-source. We have the ZeroPhone Wiki that has a lot of information already, here's a listing of software used on the ZeroPhones, and here's a listing of software that's used for them. The phone is as open-source as possible, but not fully - there are three non-free software&firmware pieces for now:

1. the Raspberry Pi bootloader
2. the ESP8266 firmware blob (an ESP module is used as a WiFi card)
3. the GSM modem firmware.

The great thing about ZeroPhone and the way it's designed (components can be replaced) you can have

1. another CPU board that doesn't need any non-free firmware (I plan to develop a BeagleBone-based replacement CPU board)
2. a USB-WiFi adapter with free firmware
3. either a GSM modem with sources available (like FreeCalypso) or something else, like a POGSAC or LoRa module

; and, as a result, have a completely open-source phone!

We've already published sourcing guidelines, and I'm working on assembly guidelines, so the project is close to achieving the "phone you can build yourself" goal. The next goal I'll work on is "phone that reliably makes calls", as in, doesn't crap out when you press the "call" button, or miss incoming calls. We've already launched ofono with the ZeroPhone modem and figured the most important parts out, and now we're writing an UI for it. Ultimately, I want to build a phone that will be accessible, reliable and free, while still being power-user friendly.

I'm here to ask some questions:

• What do you think of it? Would you use a ZeroPhone day-to-day (that's something I aim to ), if so, what kind of software/hardware features would you need?
• Do you see any problems with this project that I should take into account? Anything - hardware, software, project's goals and direction?

More about ZeroPhone:

• Hackaday.io project
• ZeroPhone Wiki
• Newsletter archive