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4. SPI Communication User Guide

For other full duplex slave devices, 16 bits slave communication should be set. The

effective data should be put to the second byte of slave sending caching which will be

received by master ESP8266.

Figure 4-2. The slave waveform of spi_byte_read_espslave read from ESP8266

4.4.2. Master SPI API Function Description

1. void spi_slave_init(uint8 spi_no)

Function:

Initialization of slave SPI mode. Conﬁgure IO interface to SPI mode, enable SPI

transmission interruption and register the function spi_slave_isr_handler.

Communication format is set at 7bits command +1bit address+8bits read/write data.

Command and address combines to be high 8 bits and the address must be 0. According

to descriptions in 3.3, it supports the three master commands, i.e. 0x04 master write and

slave read, 0x06master write and slave read, 0x0c master and slave read/write. The

communication waveform is illustrated in Figure 4-1, 4-2.

Parameter

Description

uint8 spi_no

The number of SPI module. Only input SPI(0) and

HSPI(1). Any other inputs are invalid.

uint8 data

8 bit memory address data receiving.

! Note:

Yellow line: CS, blue line: CLK, red line: MOSI, green line: MISO.

Parameter

Description

spi_no

The number of SPI module. ESP8266 processor has two SPI

modules with the same function, i.e. SPI and HSPI.

Optional values: SPI or HSPI.

Espressif

! /!

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2017.05

ESP8266 Datasheet(PDF) 33 Page - ESPRESSIF SYSTEMS (SHANGHAI) CO., LTD.