Firmware update

If you want to update the firmware to the latest version, there are two ways of flashing the Firmware binary:

A: Using USB-DFU (Device Firmware Update)

The MCU can be re-flashed via the USB port by using the on-board USB-DFU capability.

The programming process via USB requires two steps:

1. Booting the dongle into USB-DFU mode:

   The MCU has a special Bootloader in ROM memory, which provides the functionality of DFU. In order to start this process, the MCU has to be reset into DFU-Bootloader mode. This is accomplished by powering-up the device while holding the BOOT0 (DFU) signal into logic-high level (3.3V).

   

   To do this, unplug the dongle, hold a jumper (conductive material, like a piece of wire, screwdriver, paper-clip, etc.) shorting the pads indicated as "DFU" on the top-right side of the PCB, and plug the device into the USB port while shorting these 2 pins. In this case, the status LEDs should stay OFF. The jumper can be then released.

   To verify if the Bootloader has enumerated the MCU this time as a USB-DFU capable device, use the command lsusb.

   • This is the displayed information in MacOS:

   Bus 020 Device 008: ID 0483:df11 STMicroelectronics STM32  BOOTLOADER  Serial: FFFFFFFEFFFF
   

   • In a Debian distribution:

   Bus 001 Device 004: ID 0483:df11 STMicroelectronics STM Device in DFU Mode
   

   • In Windows, the Device Manager shows a “STM Device in DFU Mode” under USB devices.

2. The DFU-UTIL command:

   DFU-UTIL is a CLI application available for MacOS, Linux and Windows. In the Unix-based systems it’s available in the usual packet managers (Homebrew, apt-get, etc.). The version v0.9 is the latest one at the moment of writing and it’s been tested successfully on Debian 10 and MacOS.

   To perform the firmware programming, issue the following command, where “USBthingMNL.bin” is the application to flash in .bin format (no HEX or ELF is supported by DFU-util):

   dfu-util -a 0 -D USBthingMNL.bin  --dfuse-address 0x08000000:force:mass-erase:leave -d 0483:df11
   

   Note: In Linux, the dfu-util may need to be run as root, or a udev rule and permissions should be added.

   If everything went right, the output should look like the one below:

   Opening DFU capable USB device...
   ID 0483:df11
   Run-time device DFU version 011a
   Claiming USB DFU Interface...
   Setting Alternate Setting #0 ...
   Determining device status: state = dfuIDLE, status = 0
   dfuIDLE, continuing
   DFU mode device DFU version 011a
   Device returned transfer size 2048
   DfuSe interface name: "Internal Flash  "
   Performing mass erase, this can take a moment
   Downloading element to address = 0x08000000, size = 103880
   Erase       [=========================] 100%       103880 bytes
   Erase    done.
   Download    [=========================] 100%       103880 bytes
   Download done.
   File downloaded successfully
   Transitioning to dfuMANIFEST state
   

B: Using a debug probe connected to the SWD pads

In this case, it's necessary to solder the correspondent signals to the SWD port on the board bottom-side (do not forget to connect the 3V3 power signal or the debugger won't detect the target).

ID	Signal name	Comment
GND	Ground	System ground reference
RST	nRESET	Target reset, JTAG RESET line
DIO	SWDIO	corresponds to the JTAG TMS line
CLK	SWCLK	corresponds to the JTAG TCK line
3V3	VCC/VTref	Target reference voltage (it’s used by most debug probes to check target power and drive level converter references)

Alternatives to J-Link

Many different debug probes could be used instead (as the ones based on FT2232/OpenOCD or ST-Link™).