btstack/port/stm32-l476rg-nucleo-sx1280

BTstack Port with Cinnamon for Semtech SX1280 Controller on STM32L476 Nucleo

Cinnamon is BlueKitchen's minimal, yet robust Controller/Link Layer implementation for use with BTstack.

In contrast to common Link Layer implementations, our focus is on a robust and compact implementation for production use, where code size matters (e.g. current code size about 8 kB).

Overview

This port targets the Semtech SX1280 radio controller. The Host Stack and the Controller (incl. Link Layer) run on a STM32 MCU, with the SX1280 connected via SPI.

It uses the SX1280 C-Driver from Semtech to communicate with the SX1280. The main modification was to the SPI driver that uses DMA for full packets.

Status

Tested with theMiromico FMLR-80-P-STL4E module (see port/stm32-l451-miromico-sx1280) and the STM32 L476 Nucleo dev kit with our SX1280 Shield.

SEGGER RTT is used for debug output, so a Segger J-Link programmer is required, but the on-board ST-Link programmer and debugger can be replaced by an SEGGER J-Link OB.

Uses 32.768 kHz crytstal as LSE for timing

Support for Broadcast and Peripheral roles.

The Makefile project compiles gatt_counter, gatt_streamer_server, hog_mouse and hog_keyboard examples.

Limitation

Advertising State:

• Only Connectable Advertising supported
• Only fixed public BD_ADDR of 33:33:33:33:33:33 is used

Connection State:

• Encryption not implemented
• Some LL PDUs not supported

Central Role:

• Not implemented

Observer Role:

• Not implemented

Low power mode - basically not implemented:

• MCU does not sleep
• SPI could be disabled during sleep
• 1 ms SysTick is used for host stack although 16-bit tick time is provided by LPTIM1 based on 32768 Hz LSE.

Getting Started

Just run make. You can upload the EXAMPLE.elf file created in build folder, e.g. with Ozone using the provided EXAMPLE.jdebug, and run it.

TODO

General

• indicate random address in advertising pdus
• allow to set random BD_ADDR via HCI command and use in Advertisements
• support other regular adv types
• handle Encryption

Low Power

• enter STANDY_RC mode when idle
• implement MCU sleep (if next wakeup isn't immediate)
• sleep after connection request until first packet from Central
• replace SysTick with tick counter based on LPTIM1
• disable SPI on MCU sleep