- Wed Jan 21, 2015 4:31 pm
#7904
I would also love to have SD card access directly from the ESP8266 for a future project i have in mind..
However using bit-banged SPI to do that would be unusably slow.
Especially considering the ESP8266 has on-board high-speed SDHC interface - i'd much rather use that.
This would also free up the I2S interface which i would also need.
One small complication though is that most ESP8266 modules seem to use SHDC for their flash rom,
so one would need a way to share the SDHC bus between the connector and on-board serial flash without interfering with the latter, which seems difficult.
An easier solution might be to place the firmware binaries onto the SD card itself and switch to running from that image after the SD filesystem is successfully initialized.
you would also want to have provisions to automatically fallback to the on-board flash in the event the SD card is removed.
There would be a slight performance hit when loading code into ram due to the filesystem API, but i doubt that would be a real problem.
However using bit-banged SPI to do that would be unusably slow.
Especially considering the ESP8266 has on-board high-speed SDHC interface - i'd much rather use that.
This would also free up the I2S interface which i would also need.
One small complication though is that most ESP8266 modules seem to use SHDC for their flash rom,
so one would need a way to share the SDHC bus between the connector and on-board serial flash without interfering with the latter, which seems difficult.
An easier solution might be to place the firmware binaries onto the SD card itself and switch to running from that image after the SD filesystem is successfully initialized.
you would also want to have provisions to automatically fallback to the on-board flash in the event the SD card is removed.
There would be a slight performance hit when loading code into ram due to the filesystem API, but i doubt that would be a real problem.
