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5. SPI Overlap & Display Application Guide

Please refer to

Chapter 4 EPS8266 SPI Communication User Guide for more

information about the application method of Host SPI Module. The conﬁguration method of

Overlap mode is discussed in detail below.

5.2. Hardware Connection of SPI Overlap Mode

Pins including SD_CLK, SD_DATA0, and SD_DATA1 correspond to pins SCLK, MISO and

MOSI in two SPI modes, while pins SD_CMD, U0TXD, and GPIO0 correspond to chip

selection (CS) signals CS0, CS1, and CS2 respectively. Generally, SD_CMD connects to

the CS signal of an external Flash, while U0TXD and GPIO0 can be connect with the CS

signals of two slave devices. It can connect to the CS signal of two salve devices. Besides,

HSPI can read and write Flash data through enabled CS0, independent of SPI (e.g. Read

some pre-stored user data).

If more SPI devices are needed, device can be selected via other GPIOs, while CS0, CS1,

and CS2 are blocked by the conﬁguration register.

5.3. API Description of SPI Overlap Mode

1. void hapi_overlap_init(void)

Function:

After SPI Overlap mode has been initialized, and SPI and HSPI interfaces are invoked,

interfaces including CLK, MOSI, and MISO can be shared with SPI and HSPI interfaces to

communicate with different devices. By default, CS2 is the CS signal of HSPI interface.

Please be careful when switching CS signals during communication.

Location:

\app\user\user_main.c in the DEMO.

2. SELECT_OLED(),SELECT_TFT()

Function:

Switch the CS pin of HSPI and OLED in DEMO connects to CS2. TFTLCD connects to

CS1. Before the start of HSPI communication, macro needs to be called. The macro

deﬁnition is as follows:

#define SELECT_OLED()

CLEAR_PERI_REG_MASK(SPI_PIN(HSPI),

SPI_CS2_DIS);\

SET_PERI_REG_MASK(SPI_PIN(HSPI), SPI_CS0_DIS |SPI_CS1_DIS)

#define SELECT_TFT()

CLEAR_PERI_REG_MASK(SPI_PIN(HSPI),

SPI_CS1_DIS);\

SET_PERI_REG_MASK(SPI_PIN(HSPI), SPI_CS0_DIS |SPI_CS2_DIS)

Therefore, users can change the macro deﬁnition. For example, the following macro can be

deﬁned if HSPI is used to the operate Flash:

#define SELECT_FLASH()

CLEAR_PERI_REG_MASK(SPI_PIN(HSPI),

SPI_CS0_DIS);\

Espressif

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2017.05

ESP8266 Datasheet(PDF) 55 Page - ESPRESSIF SYSTEMS (SHANGHAI) CO., LTD.

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