README.md
1# BTstack Port with Cinnamon for Semtech SX1280 Controller on Miromico FMLR-80
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/)
17and our [SX1280 Shield](https://github.com/bluekitchen/sx1280-shield) - see (port/stm32-l476rg-nucleo-sx1280).
18On the FMLR-80-P-STL4E module, the 52 Mhz clock for the SX1280 is controlled by the MCU.
19
20SEGGER RTT is used for debug output, so a Segger J-Link programmer is required.
21
22Uses 32.768 kHz crytstal as LSE for timing
23
24Support for Broadcast and Peripheral roles.
25
26The Makefile project compiles gatt_counter, gatt_streamer_server, hog_mouse and hog_keyboard examples.
27
28## Limitation
29
30### Advertising State:
31- Only Connectable Advertising supported
32- Only fixed public BD_ADDR of 33:33:33:33:33:33 is used
33
34### Connection State:
35- Encryption not implemented
36- Some LL PDUs not supported
37
38### Central Role:
39- Not implemented
40
41### Observer Role:
42- Not implemented
43
44### Low power mode - basically not implemented:
45- MCU does not sleep
46- SPI could be disabled during sleep
47- 1 ms SysTick is used for host stack although 16-bit tick time is provided by LPTIM1 based on 32768 Hz LSE.
48
49## Getting Started
50
51For the FMLR-80-P-STL4E module, just run make. You can upload the EXAMPLE.elf file created in build folder,
52e.g. with Ozone using the provided EXAMPLE.jdebug, and run it.
53
54## TODO
55
56### General
57- indicate random address in advertising pdus
58- allow to set random BD_ADDR via HCI command and use in Advertisements
59- support other regular adv types
60- handle Encryption
61
62## Low Power
63- enter STANDY_RC mode when idle
64- implement MCU sleep (if next wakeup isn't immediate)
65- sleep after connection request until first packet from Central
66- replace SysTick with tick counter based on LPTIM1
67- disable SPI on MCU sleep
68
69