I never liked Android devices despite the superb hardware some of them have as I don't like also big Linux distributions with their systemd services and daemons or the "click yes and a ton of software will be installed in your computer",I will not talk at all for these "other" operating systems.
For years after Nokia N900 browser became unusable and had no support I was looking for a Linux phone.Working with chroot from Android starves battery very quickly and there is no reason running 2 systems on a phone When I discover Michael's Raspup it was sure that I would give it a try. The bet was to use only of the shelf,easy to fix hardware even if I had to sacrifice much of my comfort.
This is my Puppy phone,tablet,whatever,running Raspup 8.2.1.And YES it is a "brick" phone,and YES it needs a sim card,and NO (Michael) the bluetooth is not connected to raspberry but to the sim800C module (phone)
It has a 5 inch LCD,supports touch,left and right click and using xvkbd (default) keyboard plus some small applications that successfully compiled.Uses Chromium (from repository),too bad that Pale Moon does not support ARM.Now days everything is moving over http(s) and browser are complex things,very difficult to compile by inexperienced users.Sad.
The phone is connected through serial port and all functions are performed with (a lot of) interactive executable scripts.
Raspberry and phone are powered together or independently the drawback being that you can only answer a call when raspberry is off.(I am working on that)
As shown "the brick"includes:
1.raspberry pi3B and lcd attached.
2.extra wi-fi chipset (rt3070).
2.mt3608 boost converter (3.6v to 5v).Coming from early analog electronic ages I never believed that such a small switching chip can handle 1A input current,so i left space for another more powerful chip.By the way this chip is not enough for 3B+.
Below that and between raspberry and lcd a home made over voltage protection is placed which shorts module output if by chance it outputs more than 5.8v hoping that the 5A transistor will survive longer than the slow 1.5A fuse I have placed.
3.a 5v fan (sometimes necessery)
4.pi camera
5.audio amplifier directly connected to pwm output (after filter)and to a loudspeaker.If you know what you are doing beleive me the sound is very clear and loud (by all means NOT hi-fi).When raspberry is off power amplifier is not powered unless someone is calling or receive sms.
6.ISD1820 voice recording chip (and some modifications around) connected to the RI pin of sim800c and to audio amplifier.Although mic and earphone are connected to sim800C ringing is not loud enough and the ringtones are silly.
Taking into consideration that raspberry is not always powered I have recorded the ringing of my analog phone (back from the 60's) and every time someones is calling or sending sms ISD1820 rings the sound I am accustomed to, as LOUD as you wish (not very politically correct!)
7.Above ISD1820 (3mm screws) a Sony-Ericson GM-47 (already had some of them) was placed originally, having in mind that it will be replaced with sim7600E-H which has support 4G and HSPA+.Later I found that sim800C (2g) supports bluetooth so I had the option having the phone
in use (accepting calls only) without having the energy consuming raspberry powered.Since I rarely use mobile phone Ι sticked SIM800c above the batteries to give it a try.2g is good enough for my ssh sessions and for emails provided that you use a decent email client and not smtp over http.
Browsing is slooooow and this is not only because of 2g but mainly because the my internet provider is cheating my bandwidth trying to serve more gsm users but this is another story.After all browsing experience is not so great through a low quality 5 inch display.
8.Finally there are 2 906090 batteries totaling 12Ah (advertized) in parallel, enough for suppling current to raspberry for a working day and many-many days to phone alone.There is also a switching charger large enough to refill batteries when I am sleeping and small enough not to have accidents in case of malfunction.
Batteries especially lithium can be a very sad story.One of the mistakes I possibly made was that I didn't organize inside space for 18650 batteries, since it is easier to find reputable sellers for these kind of batteries.
Some issues I did not manage to fix yet:
1.Some native puppy applications don't fit in the screen,but this is not a big problem since you can run the native application (which puppy application is addressing) from command prompt.
2.When for a reason bluetooth is disconnected from a paired device (e.g. far away) SIM800C has no way to accept connection,unless you power on raspberry.I am working on this with an attiny12(obsolete but have a lot of them) with a very low power consumption.
3.If you try to travell (having this device) with an airplane you will be accused for all the bad things this world has,included damaging the ozone layer.As a result you will be lucky if not executed on the spot (I am serious).
There is a lot more to be said, but as a conclusion I can say I very pleased with my Puppy phone,
I have no words how to say "thank you" to Barry and contributors.