README.md
1# BTstack Port with Cinnamon for Semtech SX1280 Controller on STM32L476 Nucleo
2
3*Cinnamon* is BlueKitchen's minimal, yet robust Controller/Link Layer implementation for use with BTstack.
4
5In contrast to common Link Layer implementations, our focus is on a robust and compact implementation for production use,
6where code size matters (e.g. current code size about 8 kB).
7
8## Overview
9
10This 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.
11
12It 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.
13
14## Status
15
16Tested with the[Miromico FMLR-80-P-STL4E module](https://miromico.ch/portfolio/fmlr-8x-x-stlx/)
17(see port/stm32-l451-miromico-sx1280) and the
18[STM32 L476 Nucleo dev kit](https://www.st.com/en/evaluation-tools/nucleo-l476rg.html)
19with our [SX1280 Shield](https://github.com/bluekitchen/sx1280-shield).
20
21SEGGER RTT is used for debug output, so a Segger J-Link programmer is required, but the on-board
22[ST-Link programmer and debugger](https://www.st.com/en/development-tools/st-link-v2.html) can be replaced by an
23[SEGGER J-Link OB](https://www.segger.com/products/debug-probes/j-link/models/other-j-links/st-link-on-board/).
24
25Uses 32.768 kHz crytstal as LSE for timing
26
27Support for Broadcast and Peripheral roles.
28
29The Makefile project compiles gatt_counter, gatt_streamer_server, hog_mouse and hog_keyboard examples.
30
31## Limitation
32
33### Advertising State:
34- Only Connectable Advertising supported
35- Only fixed public BD_ADDR of 33:33:33:33:33:33 is used
36
37### Connection State:
38- Encryption not implemented
39- Some LL PDUs not supported
40
41### Central Role:
42- Not implemented
43
44### Observer Role:
45- Not implemented
46
47### Low power mode - basically not implemented:
48- MCU does not sleep
49- SPI could be disabled during sleep
50- 1 ms SysTick is used for host stack although 16-bit tick time is provided by LPTIM1 based on 32768 Hz LSE.
51
52## Getting Started
53
54Just run make. You can upload the EXAMPLE.elf file created in build folder,
55e.g. with Ozone using the provided EXAMPLE.jdebug, and run it.
56
57## TODO
58
59### General
60- indicate random address in advertising pdus
61- allow to set random BD_ADDR via HCI command and use in Advertisements
62- support other regular adv types
63- handle Encryption
64
65## Low Power
66- enter STANDY_RC mode when idle
67- implement MCU sleep (if next wakeup isn't immediate)
68- sleep after connection request until first packet from Central
69- replace SysTick with tick counter based on LPTIM1
70- disable SPI on MCU sleep
71
72
73
