| Silk screen mark | explain |
| SCK | SPI clock line |
| VCC | Power supply 3.3v-5v |
| SDO | SPI data output |
| SDI | SPI data input |
| GND | Ground wire |
| NCS | SPI chip selection |
| SWCLK | MCU download clock line |
| RX | TTL serial port receiving pin |
| TX | TTL serial port sending pin |
| SWDIC | MCU download cable |
After sale instructions
