Fix for PlatformIO builds

PlatformIO apparently doesn't automatically include Arduino.h in the main library CPP file the way that the Arduino build system does. This patch adds it explicitly to bb_epaper.cpp so that it builds correctly on PlatformIO.

Support for the Seeed Studio Sticky

This release adds support for the Seeed Studio Sticky (ESP32-S3 + 3.97" 800x480 B/W EPD) in the form of 2 new names for simplified initialization (EPD_SEEED_STICKY and EPD_SEEED_STICKY_4GRAY). These allow 1-line initialization of the display without having to know the GPIO connections or special power gating requirements.

Also included in this release is a low power clock example (sticky_clock) which updates the time and date with a partial (non-flickering) update every minue.

Support for Waveshare 3.97 panel and ESP32-S3 board

This release adds support for the 3.97" 800x480 SSD16xx panel as well as Waveshare's ESP32-S3 IoT product which includes this panel.

Patch to rotate TRMNL-mini 180 degrees

This release patches the 4.26" 800x480 panel definition to default to rotate it 180 degrees. The 0,0 pixel is now the upper left corner when the panel is in landscape mode and the connector is on the left.

Initial support for ESPHome

This release adds some infrastructure to allow it to be built as an ESPHome component.

Initial support for ESPHome

This release adds code to allow bb_epaper to run as a component within ESPHome. ESPHome abstracts the I/O, so a new I/O wrapper needed to be added to bb_epaper to support it.

Fast 4-gray mode for 7.5 inch UC81xx panels

With only 4 (imperfect) gray levels, it's possible to generate them without a "full flicker" update. This release adds a "fast" option to 4-gray updates on the 7.5 inch UC81xx panels (the popular ones sold by Waveshare and used in the TRMNL og). This reduces the update time from over 2 seconds to 0.6 seconds and eliminates all flashing. I will see about adding this capability to other panel/controller types.

Added named support for the XTEINK X4

This release adds a new named device (XTEINK X4) an ESP32-C3 with a 4.26" 800x480 EPD built in. I also included the start of supporting a shared SPI option for devices which share the SPI bus with a uSD card.

License update

Thanks to a generous donation by the Open Home Foundation (https://www.openhomefoundation.org/), the license of bb_epaper has been changed from Business Use to GNU GPLv3. This free, open source license allows more widespread use of the library without the need for commercial projects to license it for use in products.

low power light sleep option

This release adds a settable option to use the ESP32's light sleep during the busy-wait loop. It works in 20 millisecond increments to check on the status of the busy line. This can save significant power, especially for long update sequences like on the Spectra6.