You’ve finished designing a new PCB for your Z-Wave product and are now ready to start testing with your own custom firmware. Well, the first thing you need are bootloaders. The bootloader is a standalone application that handles upgrading the application firmware among other things. Downloading a bootloader into a Silicon Labs devkit is easy, just click on “run”. But for custom PCBs you must build it from the source code. There are two types of bootloaders needed: One for End Devices which will receive the updated firmware image over the radio, the other is for Controllers which will receive the image via the UART wires. These are similar but there are a few important differences. This post is specifically for the Z-Wave 800 series and GSDK 4.4.1. Hopefully the process will be a little easier in a future release.

End Device Bootloader – OTA

Fortunately the End Device bootloader is easy with the release of GSDK 4.4.1 (Z-Wave 7.21.1). Plug your board into a ProKit (WSTK) via the Tag-Connect connector. The WSTK should show up in Simplicity Studio v5 (SSv5) Launcher Perspective with “custom board” and the EFR32ZG23 part number on your board. Click on Detect Target if not. Ensure the Debug Mode is set to Mini (or OUT for WSTK1). Select the debug adaptor then start the New Project Wizard via File->New. Make sure the latest SDK is selected and GCC12 (not GCC10). Click on Z-Wave to filter the list and uncheck Solution Examples. Scroll down to “Bootloader – SoC Internal Storage (For Z-Wave Applications)” and select that. Click Next then rename the project to something more meaningful with the chip (ZG23A) and GSDK version (_411 for 4.1.1) for example. Build the project which should complete without error. The bootloader has a lot of security options but I recommend using the defaults. If you have a complex device and need additional code space, you can relocate the OTA buffer to an off-chip serial flash chip which will free up nearly 200K of FLASH space but no additional RAM.

Controller Bootloader – OTW

This example uses a custom PCB and the EFR32ZG23A (mid-security) chip. I start with this combination as that is what most customers will start with. Using one of the devkits causes SSv5 to automagically “know” all sorts of things about the board and what GPIOs are wired to what and what other features are available. When you pick this chip, there are zero pre-built “demos” as all of the current devkits have B (high-security) parts on them.

Start the New Project Wizard via File->New. Ensure the IDE/Toolchain is GCC12 and not GCC10. scroll down and click on the “Bootloader – NCP UART XMODEM (for Z-Wave Applications)” then click on Next. This will create a project called bootloader-storage-internal-single-zwave then append the GSDK version to that which in this case is 4.4.1 so add “ZG23A_441” to the project name to keep track of which chip and which GSDK this is for. Click on Finish then build the project. This will fail because SL_SERIAL_UART_PERIPHERAL_NO is not defined as well as several other things related to the UART.

Clearly the UART needs to be configured but a guide is needed to figure out what that might be. Plug in a Devkit and build the same project but with a different name. This project builds just fine so search for SL_SERIAL_UART_PERIPHERAL_NO. btl_uart_driver_cfg.h has a define for this for USART0. The same file in the custom project says “bootloader UART peripheral not configured”. Obviously somehow it needs to be configured. The .slcp file has Platform->Bootloader->Drivers->Bootloader UART Driver configured.

We don’t need RTS/CTS as they are not used. Configure the custom project with USART0, RX=PA09 and TX=PA08 then the project compiles. This should be the default since you MUST use a UART for XMODEM. Maybe a future release will fix this! There are other configuration items under the Bootloader Core component but generally these can remain at the defaults.

Conclusion

Bootloaders are critical to being able to field-upgrade the firmware of any Z-Wave product which is mandatory for certification. See the Bootloader Users Guide (UG489) for more details on the many options available. The process to create the Z-Wave bootloaders is a bit more complicated than it should be but I hope this guide will bring your Z-Wave product to market a little quicker. Let me know what you think by commenting below.