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a phone os

- Thu, 10 Aug 2017 09:59:00 EST CZA5DFLp No.37145
File: 1502373540803.jpg -(80244B / 78.36KB, 1000x661) Thumbnail displayed, click image for full size. a phone os
How realistic would it be to create a very basic os for an arm phone?

I'd be content if I could just boot, and maybe send a blank sms by pressing the home button or something. Has anyone ever done something like this? Do you know of any good resources to get started?
I had a basic computer architecture class, so I know how to program simple startup code and taskmanagers for x64/x86 and some microprocessors, so learning arm assembly wont be a problem. Having access to I/O, and eventually the gsm functions will probably be the difficult part.

I never really wanted a smartphone, but now I got a 2015 samsung galaxy a3 because it was only 25 euro. The battery life is really shitty (40 hours at best), so an ultra efficient os would be really cool.
Priscilla Miblinghall - Thu, 10 Aug 2017 12:34:24 EST P6PS9CBz No.37146 Reply
Take a look at the Android source code, I'm sure they have lots of examples of how to write bootloaders and SMS interfaces.

I'm not sure if this is still the case (probably is for backwards-compatibility), but maybe 5 years ago pretty much all cell phone modems used a pretty simple interface of "AT commands" which you can read more about here:

There's also really good resources for this sort of thing online, but here's one that I found really quickly:

Basically if you can figure out how your cell modem is wired to talk to your microprocessor, then you should be able to use that connection to send/receive AT commands and have the cell modem do things such as connect to the network and send/receive text messages. Other operations like making phone calls, handling MMS with embedded files, and connecting to the Internet and sending/receiving arbitrary network data might be a bit more complicated, so start with simple text-only SMS messages first.
Lillian Chinderham - Thu, 10 Aug 2017 15:33:53 EST 9QSfnS0r No.37147 Reply
A phone is basically "just" a glorified raspberry pi with a touch-screen, a mobile network module, wifi & bluetooth module, a 3 axis accelerometer, a loudspeaker and a microphone.
But: In contrast to how you would by those modules C/C++ header files to access the peripherals might not be available, and because there certainly is no schematic you'd have to find out which components they are using and how they are wired together yourself. (Or find somebody who did that)
Then you'd have implement the drivers yourself according to the devices datasheet and the reverse-engineered schematic.

If you are a professional embedded programmer it might take you a week (just spit-balling here, I'm not that) otherwise who knows.

Seriously get a prototyping board and a mobile module and 3d-print a case.
If you want it to last forever put in 2x 18650s and use a board that has a multi-cell charging controller.

Otherwise just look for old phones that have already been reverse engineered and use that.
Phyllis Fabblefane - Fri, 11 Aug 2017 01:51:37 EST P6PS9CBz No.37148 Reply
I feel like a professional embedded programmer might take a little while longer than 1 week to reverse-engineer and implement the entire layout of a modern cell phone to the point that they could run their own code on every different piece of it. They're humans too, not gods!
Basil Duckspear - Fri, 08 Sep 2017 15:10:13 EST 2mg3P58s No.37184 Reply

Holy shit, AT commands are from 1981?? wow

In general there are some neat computing concepts that trace back to the early days. However in the case of AT commands I don't think it qualifies as "neat".
Betsy Paffinghall - Sat, 09 Sep 2017 01:13:59 EST P6PS9CBz No.37185 Reply
Is that because they're somewhat antiquated, or because they've worked well since then?
Oliver Cemmlehood - Sat, 09 Sep 2017 13:41:24 EST 2mg3P58s No.37186 Reply
> because they're somewhat antiquated
yes, because of this. AT commands and telnet are similar in that way.
Oliver Cemmlehood - Sat, 09 Sep 2017 13:44:06 EST 2mg3P58s No.37187 Reply
this, by the way, is coming from someone who's a great fan of unix and lives on the cli basically so it's not that i'm *inherently* biased against "old" things. but with some things you feel that it should have been replaced a long time ago when you use it.
Jarvis Sodgemon - Sun, 10 Sep 2017 00:33:33 EST xLKzmVTo No.37188 Reply
> but with some things you feel that it should have been replaced a long time ago when you use it.

Agreed. AT commands are a pain in the ass.
Ian Brookfield - Mon, 18 Sep 2017 16:27:34 EST 4MJeso9G No.37192 Reply
You should try flash it to lineage
many report huge battery time increases with all the bloat removed

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