Feature Request: Soft SPI compatible with ESP-01? (libraries provided for starting point)

[Potato-Matic]

Basic Info

Feature request: Software SPI host that can be run on an ESP-01, with the four existing GPIO (including TX and RX)

Hardware

Hardware: ?ESP-01?
Core Version: ?2.1.0-rc2?

Description

Hi.
First off, I wanna say am absolutely astounded what igrr (thanks for https!) and company have managed to accomplish here. You guys deserve a dozen rounds of applause.

I'm currently running an ESP-01 (and have an SPI card reader with a fairly simple library) and was wondering if it's possible that you might consider implementing a software SPI host library similar to the soft I2C that already exists (and allows configuration of the GPIO pins it uses). I looked into doing this myself, and found some existing software SPI libraries that might make the job easier:

https://github.com/greiman/DigitalIO/tree/master/DigitalIO/src

It uses 'fast' digital functions (fast pinmode, fast digitalwrite, fast digitalread) but those should be easy to replace if you're familiar with the way the GPIO is accessed.

There's also this library which provides soft SPI for the teensy and a bunch of others, which might also be of use, but doesn't have a mapping defined for the ESP8266:

https://github.com/niteris/ArduinoSoftSpi

[igrr]

Closing as duplicate of #33. That issue also has some pieces of code, in assembly.