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4. Peripheral Interface

4.8. IR Remote Control

ESP8266EX currently supports one infrared remote control interface. For detailed pin

definitions, please see Table 4-8 below.

The functionality of Infrared remote control interface can be implemented via software

programming. NEC coding, modulation, and demodulation are supported by this interface.

The frequency of modulated carrier signal is 38 kHz, while the duty ratio of the square wave

is 1/3. The transmission range is around 1m which is determined by two factors: one is the

maximum current drive output, the other is internal current-limiting resistance value in the

infrared receiver. The larger the resistance value, the lower the current, so is the power, and

vice versa.

4.9. ADC (Analog-to-Digital Converter)

ESP8266EX is embedded with a 10-bit precision SAR ADC. TOUT (Pin6) is defined as

below:

The following two measurements can be implemented using ADC (Pin6). However, they

cannot be implemented at the same time.

•

Measure the power supply voltage of VDD3P3 (Pin3 and Pin4).

•

Measure the input voltage of TOUT (Pin6).

Table 4-8. Pin Definitions of IR Remote Control

Pin Name

Pin Num

IO

Function Name

MTMS

9

IO14

IR TX

GPIO5

24

IO 5

IR Rx

Table 4-9. Pin Definition of ADC

Pin Name

Pin Num

Function Name

TOUT

6

ADC Interface

Hardware Design

TOUT must be floating.

RF Initialization Parameter

The 107th byte of

esp_init_data_default.bin (0 ~ 127 bytes), vdd33_const must

be set to 0xFF.

RF Calibration Process

Optimize the RF circuit conditions based on the testing results of VDD3P3 (Pin3

and Pin4).

User Programming

Use system_get_vdd33 instead of system_adc_read.

Hardware Design

The input voltage range is 0 to 1.0V when TOUT is connected to external circuit.

Espressif

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