Lyra Series – GA2 Release Notes - Additional Information for Customers

A brief walkthrough of new features and resolved issues in our latest GA2 firmware release for the Lyra series.

Published on April 7, 2023

Lyra Series – GA2 Release Notes - Additional Information for Customers

For more information, please also refer to our latest Lyra Series – Release Notes document and our Lyra Series – AT Interface Application User Guide, available under

Download the GA2 release on GitHub:

New Features

  • You can now use the ATS 138 and 139 parameters in our AT Interface application to enable a dedicated connection and encryption indication pin. They indicate if a non-VSP connection is active and/or has been encrypted. This implementation provides a very convenient and user-friendly way to monitor the connection and encryption state of the module with e.g. the help of LEDs located on your base board. Additionally, the ATS 137 parameter can be used to set the polarity for both connection indication pins accordingly to your needs. You can select between active HIGH and active LOW polarity. Each connection pin can be configured individually. Please note that both connection and encryption indication pins are disabled by default.
  • Support for user functions have been added and implemented allowing customers to migrate from Wireless Xpress to our AT Interface application more easily and seamlessly. The usage of user functions is optional. This feature is available in conjunction with the AT+UFU and AT+SIOC commands. They can be used to trigger a specific behavior when a module event occurs. For example, you can toggle a GPIO when establishing a BLE connection, remove bonding information on disconnect, change TX power or the BLE device appearance, modify scan and advertising intervals, and a lot more – with less work to be handled and controlled by your MCU. Currently, only one AT command can be associated with each user function. Supported are SIO and BLE connection events as well as the boot event which gets triggered each time after resetting or rebooting the module. The number of user functions is limited, and 320 bytes of total storage can be used for the AT command parameters.

Resolved Issues

  • The AT+UUID command is used to specify and set a string for the UUID (Universally Unique Identifier) in hex format. For parser and application reasons, the UUID parameter can now be issued with and without quotation marks. This command for example is often used in combination with the AT+GSSB, AT+GSMD, AT+GSCB, AT+GSCE and AT+GSSE commands to define and create a custom GATT database structure as demonstrated in our Lyra Series – Custom GATT Database with AT Command Set Application Note. Please note that the Bluetooth SIG assigns 16-bit and 32-bit UUIDs for adopted services and characteristics as well as to member companies / organizations. See here for more details and a complete list of all reserved UUIDs. It’s highly recommended to generate and use 128-bit UUIDs for your own application in case a custom services and characteristics implementation is required.
  • The GATT table attributes for the Silicon Labs OTA service and characteristics have been mapped to their expected addresses. It is now possible to update Lyra and the AT Interface application Over-the-Air (OTA) using your own smartphone app or e.g. the EFR Connect mobile app from Silicon Labs. As part of the Lyra Bootloader, OTA images are uploaded in DFU mode via BLE / GATT and then transferred to the module. This is important for customers who need or want to update deployed modules in the field quickly and reliably. The reasons to do this may include bug fixes, security vulnerabilities, or new features. If you are currently running GA1 ( [Lyra S] or [Lyra P] respectively) on your modules, please make sure to first upgrade to the GA2 release via the Serial DFU (UART) or Serial Wire Debug (SWD) interface as described in our latest Lyra Series – Firmware Options and Upgrading User Guide as a workaround solution for the OTA issue. Other release versions of our AT Interface application such as GA1.1 and GA1.2 are not affected by this issue and can be updated remotely via OTA, as usual.
  • We brought the AT+PRSP functionality in line with our BL65x AT Interface implementation. The command now works as expected and can be used to complete the pairing process with the AT+PAIR command. Since each BLE module supports different I/O (Input/Output) capabilities, multiple security and pairing methods are supported for this: (1) Just Works, (2) Numeric Comparison, (3) Passkey Entry, and (4) Out of Band. Simply speaking, it specifies whether a BLE device has a keyboard input, display, buttons or no input methods at all. In our AT Interface application, you can configure the I/O capabilities for Lyra with the ATS 107 parameter. This information is then used during the initial negotiation of the pairing process. Please note that if a BLE connection is denied upon processing of an AT+PRSP request, the connection will immediately be dropped and must be performed again. This can happen due to a timeout or when incorrect data for the authentication is provided.
  • The overall power consumption has been optimized and reduced for BLE operations such as advertising, scanning and connecting. This is a huge benefit and improvement for all battery-powered wireless sensors and applications where low power usage is essential and a must-have. It is also well-suited for devices that do not send and exchange data via BLE very often and are idle for most of the time. By implementing our Low Power UART (LPUART) mode you can get down close to 3 µA. Please note that this requires an additional GPIO line output from your host. If this GPIO is HIGH, then Lyra and the AT Interface application will not try to close the UART automatically. If it is LOW (and the UART Idle Timer configured with the ATS 213 parameter is exceeded) the UART will be closed automatically to reduce the current and average consumption. Please keep in mind that in normal operating mode, the Lyra module consumes about 1 mA when the UART interface is open.
  • The VSP throughput has been improved and error rate reduced. VSP (Virtual Serial Port) is a so called “cable replacement” protocol and solution provided by Ezurio (formerly Laird Connectivity). In VSP mode, Lyra initializes the GATT server table by populating it with the VSP service (and the mandatory GAP and GATT services) on boot. Lyra then starts advertising to welcome incoming connections. Once connected, data to or from the VSP service is bridged to the UART interface. Please note that once a BLE connection is established, no further AT commands are parsed. While there is no active BLE connection, AT commands are parsed and processed in the normal way. You can find more details about our custom BLE Serial Port implementation and specification in our Custom BLE Serial Port Service Application Note.