Thanks for your interest in our product.
1. ESP8266 can indeed work in SPI-Slave mode.
About the schematic and notes of ESP8266 working in SPI-Slave Mode, you can refer to "1-HDK-ESP8266_Module Application Design Guide(EN).pdf" for details.
2. If you only use SPI interface in the occasion of transmitting commands and the like which no high speed need, we advise you to use HSPI-Slave instead.
The clock rate that HSPI supports can be the same as standard SPI. However, HSPI may be limited by the rate of processing data for there is no link-list and DMA
The communication pins are shown as below.
SPI:
SD_CLK---SPICLK
SD_D0---SPIQ/MISO
SD_D1---SPID/MOSI
SD_D2---SPIHD
SD_D3---SPIWP
SD_CMD---SPICS0
HSPI:
MTMS---HSPICLK
MTDI---HSPIQ/MISO
MTCK---HSPID/MOSI
MTDO---HPSICS
3.The SPI-Mode SDK is still in developing. With regard to the SDK of HSPI-Slave, you can e-mail us to apply for it.Statistics: Posted by Espressif_Kelly — Mon Dec 15, 2014 7:47 pm
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