Reset
There exists internal pull-up resistor in the reset pin, Pin32, which can be left dangled when it is not
used. When the chip is enabled, the reset pin is held low. In order to avoid reset caused by external
interference, the lead is generally required to be short, and no external pull-up resistor is necessary.
The enable pin CH_EN (pin 7) can also serve as a reset pin. If voltage for CH_EN pin is low, the
chipset ESP8266EX will power off. Note that this pin cannot be dangled.
2.2.3. Flash
Currently, the size of flash that we applied in our demo and modules is SPI Flash with 2MB capacity,
and the package size is SOIC_8 (SOP_8).
A resistor (package size: 0402) is connected to Pin21, the SD_CLK pin via serial port, with the aim to
lower the driving current, decrease cross-talk and external interruption, adjust the sequence, and so
on. The initial value of the serial connection resistor is 200 ohm.
Figure 6 ESP8266EX Flash
2.2.4. Crystal Oscillator
Currently, the frequency of crystal oscillators supported include 40MHz, 26MHz and 24MHz. The
accuracy of crystal oscillators applied should be ±10PPM, and the operating temperature range
should be between -20°C and 85°C. !
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