gp_display.h File Reference

Hardware displays. More...

#include <backends/gp_backend.h>

Go to the source code of this file.

Data Structures
struct	gp_backend_display_model
	A display model description. More...

Enumerations
enum	gp_backend_display_model_ids {   GP_WAVESHARE_7_5_V2 , GP_WAVESHARE_3_7 , GP_WEACT_2_13_BW , GP_WEACT_2_9_BW ,   GP_GMG12864 , GP_JLX256128_1 , GP_JLX256128_2 , GP_ST7789_1_9 ,   GP_GMT020_02 , GP_ST7789_2_8 , GP_ST7796_3_5 , GP_ST7735_1_8 }
	Supported displays. More...

Functions
gp_backend *	gp_backend_display_init (enum gp_backend_display_model_ids model)
	Initializes a hardware display.

Variables
const struct gp_backend_display_model	gp_backend_display_models []
	NULL-terminated array of display model names indexed by enum gp_backend_display_model_ids.

Detailed Description

Hardware displays.

Hardware display backends support various displays connected to hardware GPIO e.g. SPI e-ink RPi Hat. These displays are coupled with Linux input driver so that you can get a computer with a keyboard, mouse and display just by connecting display to GPIOs as well as USB keyboard and/or mouse.

In order to start an application with a hardware display backend display:$display_name string has to be passed to the display init function. This is usually done on a commandline by passing the -b option.

Attention

In order to run display backends as a regular user the user has to be in the right groups that is gpio and for SPI displays spi group as well.

SPI displays need spidev userspace SPI driver and a few GPIOs for additional signaling. The default RPi GPIO mapping is compatible with WaveShare e-ink display hats.

Attention

SPI displays require spidev (userspace SPI interface) driver that is bind to the hardware SPI driver. On RPi this is done by raspi-config where you enable SPI and reboot. After the reboot the /dev/spidev0.0 should be available.

RPi GPIO Map

Display	GPIO	Display SPI	GPIO
Reset	17	MOSI	10
Data/Cmd	25	MISO	9
Power	18	SCLK	11
Bussy	24	CS0	8

Definition in file gp_display.h.

Enumeration Type Documentation

gp_backend_display_model_ids

enum gp_backend_display_model_ids

Supported displays.

Enumerator
GP_WAVESHARE_7_5_V2	WaveShare RPi e-ink HAT 1BPP grayscale 800x480. Chip GD7965 aka UC8179c
GP_WAVESHARE_3_7	WaveShare RPi e-ink HAT 1BPP/4BPP grayscale 280x480. Chip SSD1677
GP_WEACT_2_13_BW	WeeAct 2.13 inch BW display. 250x122 Chip SSD1680
GP_WEACT_2_9_BW	WeeAct 2.9 inch BW display. 296x128 Chip SSD1680
GP_GMG12864	An 128 x 64 BW LCD display. 1BPP Grayscale 58.5x46.5mm SPI LCD display. Chip ST7565
GP_JLX256128_1	A 256x128 LCD display 1bpp mode. Chip ST75256
GP_JLX256128_2	A 256x128 LCD display 2bpp mode. Chip ST75256
GP_ST7789_1_9	170x320 1.9 TFT LCD. The display has inverse colors! Chip ST7789
GP_GMT020_02	240x320 2.0 TFT LCD. The display has inverse colors! Chip ST7789
GP_ST7789_2_8	240x320 2.8 TFT LCD. Chip ST7789
GP_ST7796_3_5	320x480 3.5 TFT LCD. Chip ST7796
GP_ST7735_1_8	128x160 1.8 TFT LCD. Chip ST7735

Definition at line 47 of file gp_display.h.

Function Documentation

gp_backend_display_init()

gp_backend * gp_backend_display_init

(

enum gp_backend_display_model_ids

model

)

Initializes a hardware display.

Warning

Using wrong display model or connecting it wrongly can damage your hardware!

The backend uses Linux input devices for keyboard and mouse support.

Parameters

model

A display model.

Returns

An initialized backend.