• Support for setting the ambient temperature through either a one-time designated API
call or on a per-update basis.
• Support for user control of the delay between completing all updates and powering
down the EPDC.
9.2 Hardware Operation
The detailed hardware operation of the EPDC is discussed in the i.MX 6DualLite
Applications Processor Reference Manual.
9.3 Software Operation
The EPDC frame buffer driver is a self-contained driver module in the Linux kernel. It
consists of a standard frame buffer device API coupled with a custom EPD-specific API
extension, accessible through the IOCTL interface. This combined functionality provides
the user with a robust and familiar display interface while offering full control over the
contents and update mode of the E Ink display.
This section covers the software operation of the EPDC driver, both through the standard
frame buffer device architecture, and through the custom E Ink API extensions.
Additionally, panel intialization and framebuffer formats are discussed.
9.3.1 EPDC Frame Buffer Driver Overview
The frame buffer device provides an abstraction for the graphics hardware. It represents
the frame buffer video hardware and allows application software to access the graphics
hardware through a well-defined interface, so that the software is not required to know
anything about the low-level hardware registers. The EPDC driver supports this model
with one key caveat: the contents of the frame buffer are not automatically updated to the
E Ink display. Instead, a custom API function call is required to trigger an update to the E
Ink display. The details of this process are explained in the
.
The frame buffer driver is enabled by selecting the frame buffer option under the graphics
parameters in the kernel configuration. To supplement the frame buffer driver, the kernel
builder may also include support for fonts and a startup logo. The frame buffer device
depends on the virtual terminal (VT) console to switch from serial to graphics mode. The
device is accessed through special device nodes, located in the /dev directory, as /dev/fb*.
fb0 is generally the primary frame buffer.
Hardware Operation
i.MX 6Solo/6DualLite Linux Reference Manual, Rev. L3.0.35_4.1.0, 09/2013
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Freescale Semiconductor, Inc.
