AS-02 is an optional accessory, it is USB Type-C converter.
AS-02 provide below feature:
1) Access AT console of LHT52 when used with USB-TTL adapter.
Connection:
✓ USB to TTL GND <--> Program Converter GND pin
✓ USB to TTL RXD <--> Program Converter D+ pin
✓ USB to TTL TXD <--> Program Converter A11 pin
2) Update firmware to LHT52 when used with DAP-Link adapter.
Connection:
✓ USB to DAP-LINK GND <--> Program Converter GND pin
✓ USB to DAP-LINK RXD <--> Program Converter D+ pin
✓ USB to DAP-LINK TXD <--> Program Converter A11 pin