Project Introduction

An ultra-small core board of STM32F103C8T6/STM32F103C6T6 uses M.2-M interface, which can greatly facilitate project hardware transplantation and simplify circuit design. (Only SW and STMISP burning programs were successfully used, and no functional verification was performed)

project instruction

• The uploaded files include the core board schematic diagram, PCB, and M.2 interface package (AD).
• The project has been shared on GITHUB: https://github.com/mark-fyq/BEIDOU-project/tree/main/tianquan/V1.0

update record

November 28, 2021

• Create open source projects.

November 29, 2021

• README adds update records and core board circuit and PCB design instructions.
• Corrected the mapping error between schematic diagram and PCB network.
• Change the SW download from the extra interface to the M.2 interface.
• Change the PIN pin of the GND network in the PCB from full copper to a "cross flower" connection with copper.

December 5, 2021

• Completed the design, layout and testing of the expansion board V1.0.
• The core board is updated to V1.1.
• Adjust the M.2 packaging model according to actual use, and add vertical M.2 interface packaging.
• Complete STMISP download verification (FLYMCU).
• Completed the upgrade design of the expansion board, added the SW independent interface, BOOT0/1 interface, and changed the M.2 interface to vertical packaging.

Precautions

• When making the core board, please choose a board with a thickness of 0.8mm and green color, and note: Do not do half-hole process (it doesn’t matter if you are rich) PS: The general process is tin plating of the pads, and the number of plugs and pulls is limited!
• The core board PCB is designed according to the reflow soldering process (actually blown with a hot air gun), so there is no space reserved for hand soldering.
• There may be differences between the PCB and the schematic, and the PCB shall prevail.
• Please note that the matching capacitor of the crystal oscillator is not necessarily 12PF, and pay attention to the merchant's remarks when purchasing.
• The size of the tact switch is 3X4X2.5 (there should be no smaller size than this).
• If you want to redraw the PCB, please note that the TOP and BOTTOM layers within 2mm near the M.2 interface should not be paved with copper to prevent short circuits caused by possible scratches; the ground PIN pins should be connected with cross flowers to prevent tombstones or shifting.
• During the test, it was found that the chip information could not be read and the core board was severely heated. Please check whether the STM32 chip is soldered normally. For chips soldered with a hot air gun, it is recommended to use an electric soldering iron to press each side to prevent false soldering (PS: Be sure to solder the chip first, otherwise The space is too small and there is no room for operation).

project progress

• Principle design (√)
• LAYOUT design（√）
• PCB layout and welding (√)
• Program burning verification (√)
• Adapter base plate design (√)
• Adapter base PCB layout and welding (√)
• Fully functional and verified

Core board hardware functions

• SW download interface (V1.1 and subsequent versions are led from the M.2 interface)
• 5V to 3V3 power conversion
• Serial to USB
• 16MBit SPI FLASH
• Power and serial communication indicators
• reset button

Core board physical picture

Core board circuit and PCB design

The AD project files are in the attachment, please download and read by yourself; all principles are open source materials and there is nothing to say;

Additional information

Please correct me if there are any mistakes!