CODEWITHSUNDEEP
androidsmartphonelte
J. Doe
J. Doe

Reputation: 49

Hardware Access

I've always liked cheap smartphones ($ 50) because with little money I can have a powerful system with lots of sensors and things like that. So I wondered if it was possible to use the hardware without using the very limited android APIs, programming it at a low level then, of course with the root. In particular I wanted to see how the LTE module worked and experiment with this having full control, the Android API does not allow it to do much.

UPDATE: I'm using something called libhybris, a wrapper that permit the use of android driver blobs in Linux.

Upvotes: 2

Views: 2297

Answers (3)

J. Doe
J. Doe

Reputation: 49

I'm using something called libhybris, a wrapper that permit the use of android driver blobs in Linux.

Upvotes: 0

CecilMerrell aka bringrainfire
CecilMerrell aka bringrainfire

Reputation: 732

The first layer of software for the phone is the bootloader. It tells the processor what partition to load into memory for executing the kernel. This is the level that is usually blocked by manufacturers because of greedy corporate reasons that are beyond the scope of this site.

The second layer of the phone is the linux kernel. Rooting is the process of gaining root user access to this layer. Root is the main administrator user account that has permission to do anything to the device. Accessing this layer is what most people refer to rooting. A large portion of the kernel is written in C, with other parts in c++. What happens at this level is where all the magic is. For most phone this is where the code for the modem resides. Talking to this can usually be done via at commands of serial. Sensors are also programmed at this level and communicate via drivers. Root access is not normally needed to read sensor data, its just a case of permissions usually.

The next level is the android operating system, the java instance runs on top of that, which in turn executes the android operating system. This is the portion that most users will see and is primarily written in java. In reality you can run any kind of user interface at this level.

A very brief view of android apps.

The android api provides a way for java developers to write "apps" that communicate with the kernel and access different parts of the phone's hardware. These apps can also be written using c++. Only until recently has google integrated c++ into android studio, but the most common and still most effective method of doing so is using the QT framework.

Upvotes: 4

Itamar Kerbel
Itamar Kerbel

Reputation: 2568

It's a bit problematic.

Hardware manufacturers do that actually.

Take into account that Android is Linux much like other distributions. The manufacturers develop hardware and then compile a version Android that sits on top of it. Each Android compilation is specifically tailored to the hardware and equipped with drivers that enable the main OS access to the different hardware capabilities.

For example, some tables will tweak the Android OS to not support cellular communication because they decided to cut costs and deliver the tablet without a cellular module.

From here you have 2 options:

  1. To hack a specific hardware and understand how the OS communicates with the hardware.
  2. Find hardware manufacturers that release some/all of their Android OS code. This is a much simpler way as you can both learn and extend the Android OS for that specific device. An example of the 2nd way is Sony who has AOSP that allows low-level access to some of the Sony devices.

Also, there is always the Android NDK which gives you a more low-level access to Android but you are still constrained by the KIT API so I'm not sure it will help you.

Upvotes: 0

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