AN12037 is a commonly adopted solution among LPC users when USB DFU Secondary Bootloader. However when customers run the demo code, they would find their PCs has problem of recognizing LpcDevice.
Scenario 1: “ LpcDevice flashes in Device Manager in a very short time then disappear for ever… “
Scenario 2: “ Device Manager can’t recognize LpcDevice…”
This is because the default demo code set DFU device only exist in 5 seconds. User must type dfu command ( dfu-util.exe -l ) very fast before de-initialize USB
So we suggest modify the code to increase the DFU device existence time.
Change
if ( dwSysTicks > 5 )to
if ( dwSysTicks > 30 )
Theoretically, the DFU existance time increases to 30 seconds. Thus we can have enough time slot to type DFU command.
