Espressif Systems ESP8266EX, Hardware User'S Manual, Page: 34 / 48

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Espressif Systems
ESP8266EX
Hardware User Guide
Before the module is powered on, pin GND RXD TXD should be lead out, and be connected with
USB to TTL serial cable (FT232 is suggested) so as to download, print log and communicate.
By default the Flash is empty. Therefore, the following procedures should be followed when you
burn the programs into the Flash:
• Before burning, set the module to work under UART Download mode;
• Pull IO15 and IO0 to low-voltage level, leave IO2 dangled;
• Burning the programs into Flash;
• Burning the program into Flash using flash downloading tools;
• After burning the programs into Flash, pull down IO15 to low-voltage level, keep IO2 dangled,
and pull up IO0 to high-voltage level. The module is then shifted from UART Download mode to
the Flash Boot mode;
• The initialisation would read and run programs from Flash after it is powered on.
Note:
• The whole operating process can be examined through the log information printed by UART
interface. If the programs written into the Flash do not function in the right way, please check the
initial settings of the working mode through logs printed from a serial port.
• Serial printing tools (for example, SecureCRT) and flash downloading tools cannot open the serial
port simultaneously.
Espressif Systems / Jun 1, 2015 34 48