ESP8266 ESP-01S serial WiFi wireless transceiver module used 4MB Flash, not 1MB flash ^^
Red: USB
Programmer selectable working mode: On-board toggle switch. UART side for serial TTL debugging by AT commands, PROG for firmware programming ^^
Red: Programmer USB to serial
TTL chip: CH340G, please check if your computer has installed the driver before use it ^^
Blue: This downloader use CH340C chip, added ESP8266 auto-download circuit, it is very convinent for user to download program, update firmware, debuggin ^^
Blue: No need connection, no need to press button, WiFi module will go into download mode automatically