Answer
Our AT Interface application and implementation for both Lyra (22) + 24 series are making use of the Silicon Labs Stack. They are based on the following − different − Bluetooth Gecko SDK (GSDK) versions:
- Lyra (22) series with Ezurio's (formerly Laird Connectivity) GA release >= 2.2 (https://github.com/LairdCP/Lyra_Firmware/releases) is based on the Silicon Labs GSDK v4.0.2 (https://www.silabs.com/documents/public/release-notes/gecko-platform-release-notes-4.0.2.0.pdf)
- Lyra 24 series with Ezurio's GA release >= 1.1 (https://github.com/LairdCP/Lyra_24_Firmware/releases) is based on the Silicon Labs GSDK v4.2.0 (https://www.silabs.com/documents/public/release-notes/gecko-platform-release-notes-4.2.0.0.pdf)
Please also refer to https://www.silabs.com/developers/gecko-software-development-kit for additional information.