|Level of support||Good|
|Bootloader||Flash with |
|User LED(s)||PC13 (lights when PC13 is LOW)|
The USB standard require a 1.5k pullup resistor on D+, but this board is known to have a wrong value (R10 on the board). It ships with either a 10K resistor or a 4.7k resistor, but it should be replaced with a 1.5k resistor, or put an appropriate resistor value (e.g 1.8k) in between PA12 and 3.3V. It is also true that some PCs are tolerant of incorrect value so, before you change the resistance, you can try if it works in your case.
Bootloader needs to be flashed using USB to Serial or ST-Link (SWD) See Flashing the bootloader
Follow the normal Installation guide
Note that after first flashing the bootloader you may have to place the board into "perpetual bootloader" mode before you can upload a sketch; place resistor between pin PC14 and 3.3V, then reset the board. You should now be able to flash a blank sketch, then remove the resistor and restart the board, after which uploading new sketches should work as expected. If you find that the IDE successfully resets your board, but dfu-util complains about no DFU-devices being present you may have to edit the maple-upload script in tools-folder, find the line where it calls upload-reset and increase the value given to it.
Where to buy
Ebay or AliExpress etc
128KB Flash on C8 version
F103C8 ST MCU is declared to have 64KB of Flash, but virtually all the C8 MCU tested have 128KB of flash instead.
At least one exception was reported in the forum, so it is not guaranteed []
The stm32duino core have two uploading board settings, one for 64KB and one for 128KB. Also the integrated serial bootloader communicates at startup that are present 128KB of flash.
- - Bootloader message:
- Using Parser : Raw BINARY
- Interface serial_w32: 57600 8E1
- Version : 0x22
- Option 1 : 0x00
- Option 2 : 0x00
- Device ID : 0x0410 (Medium-density)
- - RAM : 20KiB (512b reserved by bootloader)
- - Flash : 128KiB (sector size: 4x1024)
- - Option RAM : 16b
- - System RAM : 2KiB
The name on the forum for these boards is a reference to the Matrix, and comes from this thread on the forum It's one of the cheap STM32F103 boards that can be found from Chinese retailers. It's currently very popular with retailers, it costs about 2$.
- ARM Cortex M3
- 64KB/128KB Flash
- 20KB RAM
- Reset button
- LED on PIN PC13
- 32kHz Real time clock crystal
- Jump links on Boot0 and Boot1
- Micro USB connector for power and data
- ST-Link header on the top of the board.
- The micro-USB connector is not soldered to the board very well, and is easily broken. The best solution to this is to cover the connector in epoxy glue or hot glue. There are multiple versions of this board with different connectors. Refer to the pictures for examples.
- Analogue power and ground is connected directly to digital power and ground, which can cause additional noise on the ADC input.
- The reset button on some of these boards is very hard to press.