Bluetooth remote control

This reference design is for implementing a wireless Bluetooth Low Energy (BLE) remote control system. It demonstrates a complete solution with a bootloader for firmware updates, a transmitter application for command transmission, and a (test) receiver for processing the remote control commands.

The demo contains the following projects:

• Transmitter bootloader
  The transmitter bootloader enables over-the-air (OTA) firmware updates, ensuring the remote control stays up-to-date.
• Transmitter application
  This is the main project, it's a modern remote with the following features:
  • BLE,
  • InfraRed transmitter,
  • accelerometer,
  • gyroscope (won't be available in the first releases),
  • PDM microphone(s) (for Voice recording and forwarding via BLE),
  • up to 48 button support,
  • LED backlight,
  • activity LED.
• Receiver
  Test application to verify the correctness of the transmitter application and bootloader.
• Receiver on Host
  Desktop tool (Python-based) that acts as a BLE receiver on Windows, macOS, or Linux. Features include:
  • BLE scanning and connection using Bleak
  • ADPCM audio reception, decoding, and WAV file writing
  • Key press and battery status display
  • Optional IR capture using Flirc tools
  • Optional AI analysis using Gemini API
  • Cross-platform Tkinter-based UI

Hardware

Requirements

• Transmitter:
  • For the first product increment (PI1, until the final board):
    • BG22 Thunderboard (BRD4184A)
  • For the final solution (PI2):
    • Custom BLE remote transmitter board (BRD9402)
• Receiver:
  • BRD4187C
  • A custom expansion board.
• WSTK (BRD4001 or BRD4002) 1 or 2 is needed depending on the product increment. 1 for the custom transmitter (not for the Thunderboard) and 1 for the receiver (BRD4187C).

Setup

The Thunderboard interface is described here.
The custom transmitter board will have a Mini Simplicity connector to use with the WSTK.
During debugging the switch position of BRD9402 shall be DBVDD position, during regular operation it shall be in the BVDD position.

As per the receiver the BRD4187C needs to be put on the WSTK and the expansion board will be on the left of the WSTK, connected directly to the expansion header.
If the expansion board is not available, then the connection is detailed here.

Build

Build system dependency (these are installed if Simplicity Studio is installed):

• CMAKE
• Make
• Ninja
• ARM GCC compiler

Build types

2 type of firmware "debug" and "release" can be built on every project.
As usual debug is intended for development and release is for production.
When debug is selected "DEBUG" is defined with the value 1, otherwise it is not defined.

Build with Make

To build every binary you shall run (in the root folder)

make

The following build targets are available:

• all
  Every project in this repository, this is the default.
• transmitter_btl
  Will build bootloader/apploader for the transmitter application.
• transmitter_app
  Will build BLE remote transmitter application.
• receiver Will build the test receiver of the BLE remote.

The following arguments can be also added:

• TARGET: What shall be the selected project target. Can be: clean_build, configure_build, clean, configure or build.
  The build can be used for incremental building of a project but configure step must be at least once executed before this. The clean_build will execute clean, configure and build in this order. The configure_build will execute configure and build in this order this is the default selection.
• TYPE: What shall be the selected project build type. Can be: debug, or release.

Example:

make tag TARGET=build

Build with Docker

Dockerfile is also present in the root folder, to use it the following shall be done:

1. Install Docker: https://docs.docker.com/engine/install/
2. Build a docker image. (Default platform is x86_64.)
   docker build . -t build-env:latest
   You can also use the Makefile to do this operation. This can also recognize Apple Silicon (aarch64).
   make docker_image
3. Build the image
   docker run --rm -v .:/home -w /home build-env:latest /bin/sh -c "make all"
   With Makefile:
   make docker_build

Flashing

Can be flashed on any host with Simplicity Commander (or with any compatible ARM debugger). Simplicity Commander guide: https://www.silabs.com/documents/public/user-guides/ug162-simplicity-commander-reference-guide.pdf

Debug

Ozone is the suggested debugger.
User guide can be found here: https://www.segger.com/downloads/jlink/UM08025_Ozone.pdf

Testing and Development Tools

The remote has 1 special/dedicated button which is the "Voice/Mic" button.
When this button is pressed the remote will start recording audio from the PDM microphone(s) and will send the audio data via BLE to a connected receiver (if any).

Receiver on Host

The Receiver on Host is a Python-based desktop application that provides an alternative way to test and interact with the BLE remote transmitter. It offers a user-friendly GUI and can run on Windows, macOS, or Linux without requiring embedded hardware.
For detailed setup instructions, configuration options, and feature documentation, see the Receiver on Host README or check directly the Setup chapter.

BLE Voice Testing with Simplicity SDK

Alternatively, the BLE voice transmission can be verified with a PC application which is present in the Simplicity SDK.
The project name is "BT Host Voice", default location (Simplicity SDK relative path): app/bluetooth/example_host/bt_host_voice/.
A How-To can be found in the voice SoC application example: app/bluetooth/example/bt_soc_voice/readme.md.

Note that the MAC address of the remote transmitter shall be provided to the PC application, otherwise it won't be able to connect to the remote transmitter.
If encoding is enabled then SYS_CNF_VOICE_ENCODE_SEND_STATE shall be 0 because the PC application does not support the encoding state (only the remote receiver but for that this macro shall be 1). If encoding is disabled (add -e flag) then SYS_CNF_VOICE_ENCODE_SEND_STATE can be 0 or 1, it does not matter.

Example commands:

  ./exe/bt_host_voice -u /dev/tty.usbmodem0004402543721 -a 34:25:B4:10:AE:A9 -s 16000 -o brd9402_test_audio
  cd scripts/raspbian ; sh convert.sh ; cd ../..

The current path in the example is <SDK_PATH>/app/bluetooth/example_host/bt_host_voice/.
The convert.sh script will search for the audio data on the Desktop by default so you need to copy the audio file there or modify the script to search in the current directory.

Libraries

• Simplicity SDK 2024.12.2

License

• See the LICENSE.md file for details.
• If ST accelerometer is used (LIS2Dx12), this BSD 3 license of ST must also apply.