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3 FIRMWARE

A specific firmware example has been developed to illustrate this application note: ST7 USB

LS DFU Demo for non-USB applications.

This firmware has been created starting from the ST7 USB LS DFU Demo firmware, itself

based on the ST7 USB LS Library and ST7 USB LS EvalKit.

The main changes concern the size optimization of the USB Library and the DFU layer in

order to use a little space as possible in Sector 0. Currently the space required by the USB Li-

brary and the DFU layer is around 2 Kbytes. This optimization leaves 2 Kbytes of code for run-

ning the application during the DFU process or using it for code that does not need to be up-

graded.

This firmware is compatible with Cosmic and Metrowerks compilers.

3.1 MAIN APPLICATION FUNCTION EXAMPLE

void main(void) {

Init_Appli();

while (1) {

// MANDATORY: USED TO GO INTO DFU MODE WHEN THE USB CABLE IS PLUGGED

if (ValBit(PBDR, 5)) { // Check if Vbus is present ?

Stop_Appli();

WDGCR = 0x80; // MCU Reset

}

else {

Application();

}

} // End of while

} // End of main

3.2 DEVICE INFORMATION EXAMPLE

As the application is non-USB, we don’t have the USB descriptors. The descriptors normally

contain strings like: Manufacturer name, Product name, firmware version, ...

Because it is very useful to know which product is connected to the USB, a kind of string de-

scriptor has been created in this project.

The principle is very simple: a fixed table contains the address and the size of these string de-

scriptors (for example the Product name and its version). The host retreives this information

using a DFU_UPLOAD request. It is then possible to display these strings on a Graphical User

Interface.