ESP-01/07/12 Series Modules User's Manual V1.4
Copyright © 2017 Shenzhen Ai-Thinker Technology Co., Ltd All Rights Reserved
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design of the module and the placement of the antenna on the bottom plate according
to this guide.
Option 1 (recommended):
Place the module along the edge of the PCB board, and the antenna is placed
outside the frame or along the board and the bottom is hollowed out;
Option 2:
The module placed along the PCB board side, the antenna placed along the
board and the bottom of the hollow;
Option 3:
Place the module along the board side of the board, the antenna placed along the
board and the bottom are not copper.
Figure 4.7 ESP-12S antenna placement instructions
4.3 Module Peripheral Routing Instructions
The ESP8266 series modules integrates high-speed GPIO and peripheral
interfaces, which can cause severe switching noise. If some applications require high
power and EMI characteristics, it is recommended to connect 10 to 100 ohms in
series on digital I/O lines. This can suppress overshoot when switching power
supplies and make the signal smooth. Series resistance can also prevent electrostatic
discharge (ESD) to some extent.
