Sharp memory display generic shield

Overview

This is a generic shield for Sharp memory pixel LCD. It supports displays of LS0XX type. These displays have an SPI interface and few other pins. Note that the SCS is active high for this display.

The DISP pin controls whether to display memory contents or show all white pixels, this can be connected directly to VDD, to always display memory contents or connected to a gpio. If devicetree contains disp-en-gpios then it will be set to high during driver initialization. Display blanking apis can be used to control it.

Sharp memory displays require toggling the VCOM signal periodically to prevent a DC bias occurring in the panel as mentioned in the appnote [1] and datasheet [2]. The DC bias can damage the LCD and reduce the life. This signal must be supplied from either serial input (sw) or an external signal on the EXTCOMIN pin.

Currently the driver only supports VCOM toggling using the EXTCOMIN pin (EXTMODE pin is connected to VDD). When extcomin-gpios is defined, driver starts a thread which will toggle EXTCOMIN at extcomin-frequency frequency. Higher frequency gives better contrast while lower frequency saves power.

To use a different method of toggling for example pwm, user may not define extcomin-gpios and implement their preferred method in application code.

Pins Assignment of the Generic Sharp memory Display Shield

Pin

Function

SCS

Serial Slave Select

SI

Serial Data Input

SCLK

Serial Clock Input

EXTCOMIN

VCOM Inversion Polarity Input (VCOM can be controlled through SW)

DISP

Display ON/OFF switching signal (Can be connected directly to VDD)

EXTMODE

COM Inversion Selection

Current supported displays

Following displays are supported but shield only exists for LS013B7DH03. Other shields can be added by using the LS013B7DH03 as a reference and changing the width, height, etc configurations.

LS012B7DD01 LS012B7DD06 LS013B7DH03 LS013B7DH05 LS013B7DH06 LS027B7DH01A LS032B7DD02 LS044Q7DH01

Display

Shield Designation

LS013B7DH03

ls013b7dh03

Requirements

This shield can only be used with a board that provides a configuration for Arduino connectors and defines node aliases for SPI and GPIO interfaces (see Shields for more details).

Programming

Set --shield ls013b7dh03 when you invoke west build. For example:

# From the root of the zephyr repository
west build -b nrf52840dk/nrf52840 --shield ls013b7dh03 samples/subsys/display/lvgl

References