How to customize the STM32MPU distribution for Android

This articles explain how you can customize the STM32MPU distribution for Android™. It's intent to be used by distribution package users.

1 Prerequisites

The environment used must have been installed using the Distribution Package adapted to your microprocessor device. See Distribution_Package.

To execute the following instructions, go to your distribution root directory and initialize your environment:

 source build/envsetup.sh
 lunch aosp_<BoardId>-userdebug

2 Layout configuration

The memory layout can be configure through the android_layout.config file located in device/stm/<STM32Series>/layout. It contains all the necessary data.

When changes are complete, reload the environment:

 source build/envsetup.sh
 lunch aosp_<BoardId>-userdebug

2.1 Memory type

To adapt your build to the required memory, change the PART_MEMORY_TYPE parameter in the android_layout.config file. PART_MEMORY_TYPE values can be:

• sd
• emmc

2.2 Memory size

To adapt your build to your memory size, change the PART_MEMORY_SIZE parameter in the android_layout.config file. PART_MEMORY_SIZE values can be:

• 4GiB (4 Gbytes)
• 8GiB (8 Gbytes)

Its value must match the parameter of name PART_<Memory size>_MEMORY_MAX_SIZE, located at the end of the file.

It might need to be changed. For example:

PART_8GiB_MEMORY_MAX_SIZE 7432M x1 sd

The 7536M must be adapted if your memory size is lower that the value defined.

To find the correct value, execute the command below:

 sgdisk -p /dev/mmcblk<x>

It displays the following information:

Disk /dev/mmcblk0: 15433728 sectors, 7.4 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXX
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 15433694
Partitions will be aligned on 2-sector boundaries
Total free space is 0 sectors (0 bytes)

The first line show the microSD card available size: here 15433728 sectors.

To calculate the size in MiB (Mbytes):

size = (NbSectors * SectorSize) / 1024 / 1024
In this example: (15433728 * 512) / 1024 / 1024 = 7536 MiB

Report this value in PART_8GiB_MEMORY_MAX_SIZE:

PART_8GiB_MEMORY_MAX_SIZE 7536M x1 sd

For more details, refer to the README file located in the same folder.

2.3 Partition size

To change the size of a partition, modify it in the android_layout.config file.

Adapt the following parameters:

PART_<NAME> <PART_SIZE> <PART_NB> <PART_LABEL> <PART_SUFFIX> <PART_ENABLE>
NAME: name of the local variable (last partition MUST start with PART_LAST_)
PART_SIZE: as xxxMB or xxxKB or xxxGB
PART_NB: number of instances of partition (x1 or x2)
PART_LABEL: name of the partition label
PART_SUFFIX (optional): name of the suffix in case PART_NB equal x2 (_a/_b by default)
PART_ENABLE (optional): device for which the partition is only applicable (sd)

Then adapt every FlashLayout_*.tsv under device/stm/<STM32Series>/layout/programmer to match your changes.

To do this, use the device/stm/<STM32Series>/script/layout/build_tsv.py script.

3 Audio configuration

The audio.stm.xmlconfiguration file is stored in device/stm/<STM32Series>/<BoardId>/media/audio.

Refer to How to change audio device for Android for more details.

4 Light configuration

The lights.stm.xml configuration file is stored in device/stm/<STM32Series>/<BoardId>/lights.

This file allows associating the list of LEDs with the Android light IDs:

• notifications
• attention
• backlight
• keyboard
• buttons
• battery
• bluetooth
• wifi

First identify the list of available LEDS (it is recommended to stub the list of lights by adding device="stub").

Open a terminal on the device:

 adb shell

Get the list of available labels:

 ls /sys/class/leds/

In the device-tree associated to your device, you can check the list of <label> names in the <led> structure.

Then associate the following Android light IDs with the correct label.

5 Thermal configuration

The thermal.stm.xml configuration file is stored in device/stm/<STM32Series>/<BoardId>/thermal.

Thermal information can be returned for the following temperature types:

• CPUx (one index for each CPU)
• GPU
• Battery
• Skin (external part of the device)

First identify the list of available thermal zones (it is recommended to stub the list of thermal data by adding stub="1" and adding fixed values for threshold,shutdown and threshold_vr_min).

Open a terminal on the device:

 adb shell

Check the list of available zones:

 ls /sys/class/thermal/

Check each thermal zone type. Below the example corresponding to the case of two thermal zones with indexes 0 and 1:

 cat /sys/class/thermal/thermal_zone0/type
 cat /sys/class/thermal/thermal_zone1/type

For each zone, check the list of available trip points (not systematically present). Below the example corresponding to the case of two trip points with indexes 0 and 1 for thermal zone 0:

 cat /sys/class/thermal/thermal_zone0/trip_point_0_type
 cat /sys/class/thermal/thermal_zone0/trip_point_1_type

Update the configuration file according to the information returned:

• If no information is available, you can stub the list of thermal data by adding fixed values stub="1"
• If a thermal zone is associated to one or several temperature types: stub="0"
  • No trip point data: fix the values in the file.
  • Trip point data: put all data at 0 and add each trip index and type values in the file.

6 Bluetooth configuration

The configuration is stored in bdroid_buildcfg.h located in device/stm/<STM32Series>/<BoardId>/network/bt.

Bluetooth is enabled in device/stm/<STM32Series>/<BoardId>/BoardConfig.mk:

BOARD_HAVE_BLUETOOTH := true
BOARD_HAVE_BLUETOOTH_LINUX := true

Add the path of the configuration file overlay bdroid_buildcfg.h:

BOARD_BLUETOOTH_BDROID_BUILDCFG_INCLUDE_DIR ?= device/stm/<STM32Series>/<BoardId>/network/bt

The Android Bluetooth stack (located in system/bt) can be configured through the device/stm/<STM32Series>/<BoardId>/network/bt/bdroid_buildcfg.h file.

It must at least contain the definition of the Class of Device (CoD) (refer to the Bluetooth Specification for additional information):

#define BTA_DM_COD {0x5A, 0x01, 0x1C}

Additionally, it can contain the Bluetooth Stack profile configuration. If a variable is not set in this file, the default configuration is used in the stack.

By default, all the profiles are selected (see system/bt/include/bt_target.h). Example for the PAN profile:

#ifndef BTA_PAN_INCLUDED
#define BTA_PAN_INCLUDED TRUE
#endif

To disable it, add the following line in bdroid_buildcfg.h:

#define BTA_PAN_INCLUDED FALSE

Refer to Android Bluetooth for more details

7 Wi-Fi configuration

The configuration is stored in device/stm/<STM32Series>/<BoardId>/network/wifi.

You can change the following parameters:

• p2p
• wpa supplicant
• dhcp

Refer to How to change Wi-Fi device for Android for more details.

8 Modification of the Android distribution

The list of changes performed during the <STM32Series>setup (ex: stm32mp1setup for STM32MP1 series) can be adapted by modifying the android_patch.config available in device/stm/<STM32Series>/patch/android/ file.

First retrieve the original configuration:

 <STM32Series>clear -p

Then adapt the file (add or/and remove list of commits and patches).

Some rules must be respected for adding patches:

• Patch files shall be added with the relative path to device/stm/<STM32Series>/patch/android/ directory.
• Patch files shall be added without the .patch suffix.
• Patches shall be added in the correct order.

Some rules must the respected for removing patches:

• Test the new configuration on the targeted directory by applying the patches manually (generate them again if required).
• Do not remove patches and commits with do not modify mention.

When this is done, apply the new configuration:

 <STM32Series>setup

Then rebuild the distribution to take into account your changes:

 make -j

eval,disco (Generic term used, to complete configuration modules paths depending on used board)

stm32mp1

Central processing unit

Graphics Processing Units

technology for wireless local area networking with devices based on the IEEE 802.11 standards

eval,disco (Generic term used, to complete configuration modules paths depending on used board)

stm32mp1

Central processing unit

Graphics Processing Units

technology for wireless local area networking with devices based on the IEEE 802.11 standards