Support for SPI0 in SPI library

[Shibonja]

Hi guys,

First of all Thanks for the good work, you made development much easier with esp integration with Arduino IDE.
I have one question if someone can answer on them.

1. are the extra SPI pins on esp-12e supported in Arduino IDE and if yes are they using bit-banging.

ESP8226-12E https://www.adafruit.com/products/2491

Thanks in advance, Haris.

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[igrr]

SPI library uses hardware HSPI (a.k.a. SPI1) peripheral (pins 12-15).
Extra pins on ESP-12E are connected to SPI0 peripheral, which is not supported by SPI0 library at the moment.

[Shibonja]

Hi @igrr ,
Thanks for quick answer.
Are you planning to add support for them in future releases?

[igrr]

Actually I did implement this in a hacky manner about a month ago, need to revisit these changes and clean up the code.

[Shibonja]

Hi @igrr ,
I ordered a few ESP8226-12E, so if u need any help, maybe I can be at your service, also I am not a C/C++ guru but I can find my way around.

[Links2004]

is SPI0 not shared with the flash?
so all the SPI code need to be in ram,
may gives problems with other interrupts too?

[igrr]

Actually this is done as follows: you are still using SPI1 peripheral (i.e. registers are the same), but its pins are mapped to the same pins as SPI0. There is a hardware arbiter which can demultiplex two SPI peripherals to the same physical set of pins, controlling two CS lines automatically. SPI0 has higher priority, so flash requests are still serviced, and you can use cached code. Access times via SPI1 become a bit unpredictable in this mode, but you can have an SPI peripheral and keep pins 12-15 free at the same time.

[reaper7]

@igrr - very interesting...is there any chance for tests this solution?

[steffenmauch]

@igrr Is there any possiblity to test your solution?