How to flash firmware to STM32Fx

Some of stm32 boards have build-in USB DFU protocol support. For those you can use tools like DFuSe demo from ST or open-source dfu-util to directly upload firmware image through USB. Its obvious and i’m not going to describe it here. (You can find full list of DFU-enabled MCUs in app note AN3156).

For those MCUs without DFU support (like STM32F103C8T6 used in BluePill) you need separate hardware programmer, for example ST-Link V2 Mini

You need to connect it to dev mini board and wiring is simple:

ST-Link        STM32F103C8T6
3.3V     ---       3.3V
GND      ---       GND
SWDIO    ---       DIO
SWCLK    ---       DCLK

Like this:

Then you have to download from st.com and install ST-Link Utility. When you connect programmer first time, it is recommended to upgrade firmware of programmer itself. Open ST-Link Utility program and choose in menu ST-Link -> Firmware update, then click Device Connect and if newer firmware is available,  you will see something like this:

Click Yes and newer firmware will be installed.

Then you have to open file with firmware and choose Target -> Connect. If your wiring between programmer and board is correct, you can see info about your MCU:

The next step is necessary and it’s full chip erase. Choose Target -> Erase Chip.

Then you have to choose Target -> Program and thats all!

 

If my firmware for Pedal & Buttons controller already flashed to the board and needs to updated or reflashed than programmer will can’t connect to the board. Its because I disabled SWD and used its pins as normal GPIO. We have here 2 choices:

1. Switch both yellow jumpers, so your board will load directly to internal bootloader
2. Make a «Connect under Reset». So in this case you have to do:

• choose Target -> Settings in ST-Link utility
• choose Hardware Reset in Reset Mode
• push and hold Reset button on the board
• click OK in ST-Link utility
• release Reset button

ST-Link utility should now connect to stm board and you can flash a newer firmware. (don’t forget to make full chip erase!)

 

PS. If you have another development board, for example STM32F4Discovery, you can use its build-in programmer. In this case you need to remove both CN3 jumpers and use Disco’s SWD connector this way:

STM32F4Discovery        STM32F103C8T6
3.3V              ---      3.3V
PIN2              ---      DCLK
PIN3              ---      GND
PIN4              ---      DIO

Something like this: