How to get ch55x's Unique ID about ch55xduino

[DeqingSun]

  USBSerial_print_ub(*(__code uint8_t*)(0x3FFC), HEX);
  USBSerial_print_c(' ');
  USBSerial_print_ub(*(__code uint8_t*)(0x3FFD), HEX);
  USBSerial_print_c(' ');
  USBSerial_print_ub(*(__code uint8_t*)(0x3FFE), HEX);
  USBSerial_print_c(' ');
  USBSerial_print_ub(*(__code uint8_t*)(0x3FFF), HEX);
  USBSerial_print_c(' ');
  USBSerial_print_ub(*(__code uint8_t*)(0x3FFA), HEX);
  USBSerial_print_c(' ');
  USBSerial_print_ub(*(__code uint8_t*)(0x3FFB), HEX);
  USBSerial_print_c(' ');
  USBSerial_println();

I get

3 C0 BC 4C 31 52

[nerdralph]

0x3FFB isn't part of the unique ID. The datasheet says it is reserved "保留", though it seems to be used for the chip ID, just like SFR CHIP_ID at address 0xA1. With a CH551, this should output 51.
p.s.:
I just tried it on a CH551, and it looks like I'm wrong about 0x3FFB being the same as CHIP_ID. here's what I get:
98 B0 4B 47 9D 32

[wukongxuetang]

I am using ch552,Test the code,I get 1C 7E 80 58 31 52;
I test another ch552g,get uid is 03 7E 80 58 55 5A,0x3FFB value is 5A,not same with chip_id,