CAMBRIDGE, UK, November 26, 2002, Crossware (www.crossware.com), a leading embedded software tools developer, has added support for multiple application debugging to its entire family of debuggers. Using this facility, programmers can rapidly develop applications that are to be transferred from a remote location and programmed into flash using a boot loader running on the target board. Simultaneous source level debugging of both the boot loader and the applications allows the programmer to observe and control the operation of the complete software system.

Multiple application debugging facilitates more rapid development by allowing the application to be developed in the real environment using a minimal version of the boot loader. While one developer is engaged in developing the boot loader, another developer can use a preliminary version of the boot loader to develop the application. Multiple application debugging is supported while simulating too, allowing development to proceed in the absence of hardware.

An increasing number of systems take advantage of the re-programmability of flash memory by allowing the application software to be updated or replaced remotely. Some microcontrollers have in-built facilities to achieve this but often the developer will need to develop both a boot loader and the applications that go with it.

The boot loader includes facilities for both receiving the stream of data that constitutes the application and for programming this data into flash memory. Once the application is fully programmed into flash, the boot loader can transfer control to it. Control is transferred back to the boot loader when the application needs to be updated or replaced, or when a second application on the target board needs to run.

Typically, the programmer will develop the boot loader first and make sure that it can receive and program the application into flash memory. However, when control is then passed to the application, the programmer would, without multiple application debugging, only be able to step through the application at the assembly code level - no source level debugging information being available.

The programmer would get around this problem by developing the application separately, only running it via the boot loader once it was developed. This is not ideal because there may be problems that only occur when the application is running in conjunction with the boot loader. Identifying these problems is not easy.

Crossware's multiple application debugging facility avoids these issues and provides additional benefits too. The boot loader and the application can be developed simultaneously. With a preliminary version of the boot loader running in the debugger and a preliminary version of the application ready to test, the debugger can be instructed to load the application into the target board's memory. The programmer can then test that the boot loader will transfer control to the application even before any of the boot loader code for programming flash has been written. When control passes to the application, all of the debug records for the application are available to the debugger. The developer can step through the boot loader program at the source level and can continue to step through the application at the source level too. Source level breakpoints can be simultaneously set in both the boot loader and the application.