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4. Peripheral Interface

RF Initialization

Parameter

The value of the 107th byte of

esp_init_data_default.bin (0 ~ 127 bytes),

vdd33_const

must be set to the real power supply voltage of Pin3 and Pin4.

The unit and effective value range of vdd33_const is 0.1V and 18 to 36,

respectively, thus making the working power voltage range of ESP8266EX

between 1.8V and 3.6V,

RF Calibration Process

Optimize the RF circuit conditions based on the value of vdd33_const. The

permissible error is ±0.2V.

User Programming

Use system_adc_readinstead of system_get_vdd33.

���� Notes:

esp_init_data_default.bin is provided in SDK package which contains RF initialization parameters (0 ~

127 bytes). The name of the 107th byte in esp_init_data_default.bin is vdd33_const, which is defined as

below:

calibration process of ESP8266EX itself. RF circuit conditions should be optimized according to the

testing results.

•

When 18 =< vdd33_const =< 36, ESP8266EX RF Calibration and optimization process is implemented

via (vdd33_const/10).

•

When vdd33_const < 18 or 36 < vdd33_const < 255, vdd33_const is invalid. ESP8266EX RF

Calibration and optimization process is implemented via the default value 3.3V.

Espressif

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