btstack/port/stm32-l451-miromico-sx1280

BTstack Port with Cinnamon for Semtech SX1280 Controller on Miromico FMLR-80

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 the Miromico FMLR-80-P-STL4E module and our SX1280 Shield - see (port/stm32-l476rg-nucleo-sx1280). On the FMLR-80-P-STL4E module, the 52 Mhz clock for the SX1280 is controlled by the MCU.

SEGGER RTT is used for debug output, so a Segger J-Link programmer is required.

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

For the FMLR-80-P-STL4E module, 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