Flashing Firmware instructions

The firmware can be easily flashed on to the Mini Gerbil and Super Gerbil boards via the following flashing firmware instructions.

Step 1 – Preparations:

  • Download the STM Link utility here.
  • For the Mini Gerbil – take a photo of JP9 jumper in position before removing it.  Note: when in position this jumper isolates the line which allows reprogramming of the STM MCU. It must be removed to allow programming.

Step 2. Wire up your controller board to the ST LINK V2 dongle as following. Beware that some dongles have different pin layouts and label errors (e.g. SWDIO/SWCLK swapped):

Controller board to Dongle

  • 3V3 -> 3.3 Pin 8 of the dongle
  • IO -> SWDIO Pin 4 of the dongle
  • CLK -> SWCLK Pin 2 of the dongle
  • GND -> GND Pin 6 of the dongle

The SG boards have the labels on the silkscreen, jp8 programmer port.

Dongles – beware of variants. Note the location of the keyed opening and the small bar on the pin picture

Note: The board should be disconnected from power when programming it via the dongle.

Step 3. Start the STM LINK Utility software. For the Super Gerbil, configure it as shown in the screen shots below (SWD, Freq 4MHz, Connect under reset, Hardware reset).

ST Link Utility Settings

Click OK and in the main console of the ST Link Utility click on the icon with the plug Connect.

Note: SuperGerbils need a hardware reset since we use the SWDIO/CLK as GPIO ports. So click on connect followed immediately with a push on SG’s hardware button to avoid setting these to GPIOs via the firmware.

Third icon on the left – Connect to Target

Step 4. Once connected, load the relevant firmware. For example:

Note: Ensure you save as plain text with a .hex extension (not as a .txt or HTML extension). The easiest way is to click on RAW, then right click Save As and edit the file ending to .hex Or, you can just download all files as a ZIP file and extract just the one you need, the .hex file.

Step 5. Flash the firmware via 6th icon (book/pencil icon) on the left. The firmware is being flashed. Failing to flash can be caused by:

  • swapped SWDIO/SWCLK connections (we had a few of those dongles with erred labels),
  • loose Dupont connectors,
  • (for SG) reset hardware button pushed first before connect or too early (press it after connect with a 1 sec delay).
  • you might need to erase the existing flashed firmware first via the 5th icon of the left (eraser icon).

Step 6. For the Mini Gerbil, reinstall jumper lead JP9 in original position to avoid memory erasure

Hope you enjoyed the flashing firmware instructions and start experimenting with the firmware, it’s yours!

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