Spi Communication User Guide; Functional Overview; Esp8266 Spi Master Protocol Format; Communication Format Supported By Master Spi - Espressif ESP8266 Technical Reference

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4.

4.1. Functional Overview

ESP8266 SPI module is used for communication with devices supporting SPI protocols. It
supports the SPI protocol standard of 4 line communication CS, SCLK, MOSI, MISO
the electrical interface. ESP8266 SPI module has special support for FLASH memory in
the SPI interface. Therefore, master and slave SPI module have its corresponding hardware
protocol to match with the SPI communication device.

4.2. ESP8266 SPI Master Protocol Format

4.2.1. Communication Format Supported by Master SPI

Master ESP8266SPI communication format is command+address+read/write data, which
is,
Command: a must; length: 1 ~ 16 bits; master output and slave input (MOSI).
•
Address: optional; length: 0 ~ 32 bits master output and slave input (MOSI).
•
• Read/write data: optional; length: 0 ~ 512 bits (64 Bytes); master output and slave
input (MOSI) or master input and slave output (MISO).

4.2.2. Master SPI Communication Format Supported by Current API

The API function of ESP8266 SPI has two master initialization modes: one supports most
of the general signals and the other is designed for driving a colored LCD screen. The
device needs non-standard 9 bits SPI communication format. Please refer to Section 4.4.1
for detailed information.

4.3. ESP8266 SPI Slave Protocol Format

4.3.1. SPI Slave Clock Polarity Configuration Requirement
The master device clock polarity configuration of ESP8266 SPI slave communication
should be set with idle low power , rising edge sampling and falling edge data
transformation. Please make sure to keep low power for CS in a 16's reading/writing
process. If the CS power is raised to high level while sending, the internal state of slave will
be reset.
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SPI Communication User
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4. SPI Communication User Guide

Guide
in
2016.05