ESP8266 Community Forum

- Tue Feb 19, 2019 1:58 am #80652 Hello,

I was wondering if I can use the SDIO peripheral on GPIOs[9..14] on the ESP8266 module. I have only U0RXD and U0TXD tied to the main uC of the project because I plan to use the ESP8266 as a WiFi co-processor for future firmware updates. However, I have an SD card module connected to the main uC and it would help a lot if I can access the file system on the card over the Wifi connection so I can exchange data using PC or mobile phone.

As far as I know, GPIOs[9..14] are used to access the internal flash, so I just wanted to make sure using the SDIO on those pins won't conflict with the firmware and functionality on the ESP8266.

Thank you!

- Tue Feb 19, 2019 2:42 am #80655 AFAIK the SD interface is an alternative to using the SPI flash for user firmware. The parallel use as simple storage device might fall under "Extended mode" from https://arduino-esp8266.readthedocs.io/ ... s.html#spi

- Tue Feb 19, 2019 3:22 am #80656

AFAIK the SD interface is an alternative to using the SPI flash for user firmware. The parallel use as simple storage device might fall under "Extended mode" from https://arduino-esp8266.readthedocs.io/ ... s.html#spi

There are several points to be cleared in your reply. First of all, what do you mean by "alternative to using SPI flash for user firmware"? Do you mean one could program the SPI flash onboard over SPI? Also, the "parallel use as simple storage device" refers here to the SPI flash itself? But I do not intend to use the flash as the storage medium. What I want is to interface SD card to the ESP8266 module, that's it!

I read about the "extended mode" but I guess it has nothing to do with the SDIO interface. It's only about assigning the SPI to the same pins the controller uses to access the flash.

Perhaps the only way to do it is to interface the SD card module using SPI?

- Tue Feb 19, 2019 3:07 pm #80665

Perhaps the only way to do it is to interface the SD card module using SPI?

most probably ... yes

"alternative to using SPI flash for user firmware"?

meaning ... boot from SD instead of SPI flash

But I do not intend to use the flash as the storage medium.

not the flash, the SD, parallel to the spi flash on the hwspi