DocID024106 Rev 1

5/13

AN4227

Hardware description

•

Some LEDs have been mounted on the board, thus allowing a real-time check of what

the demonstration board is performing. LEDs D1 and D5 give feedback about the

supply and successful enumeration while the purpose of D2, D3 and D4 is to check the

status of the board. D2 and D3 will alternately blink while the STM32 is in DFU mode

(before the dedicated firmware has been correctly loaded into the flash memory of the

microcontroller). Checking the PC “Device Manager”, the STM device in DFU mode will

appear (see Figure 3 below).

Figure 3. Device manager when STM32 is in DFU mode

The audio hub boards are provided by ST with the firmware already loaded; the DFU

section has been included to allow a firmware update by the user with no need for flash

loader kits and is directly supported by the APWorkbench tool. The status of LEDs D1-D5 is

summarized in the table below.

Table 3. LED status

D1

D2

D3

D4

D5

ON: USB

enumeration

successful

Blinking: DFU mode

Off: Firmware correctly

downloaded

Blinking: DFU mode

Off: Firmware correctly

downloaded

Off: Firmware correctly

downloaded

ON: Board supplied