7.8inch e-Paper HAT

7.8inch e-Paper raw Panel 1872 × 1404, 7.8inch EPD panel without driver board

7.8inch e-paper HAT 1872 × 1404, 7.8inch EPD HAT for Raspberry Pi, USB/SPI/I80/I2C interface

{{{name3}}}

{{{name4}}}

{{{name5}}}

Primary Attribute Category: {{{userDefinedInfo}}}: {{{userdefinedvalue}}} Brand: Waveshare

Website International: Waveshare website Chinese: 官方中文站点

Onboard Interfaces I2C I80 SPI USB

Related Products 4.3inch e-Paper UART Module 13.3inch e-Paper HAT 13.3inch HDMI e-Paper 12.48inch e-Paper Module 12.48inch e-Paper Module (B) 10.3inch HDMI e-Paper 10.3inch e-Paper HAT (D) 10.3inch e-Paper HAT 9.7inch HDMI e-Paper 9.7inch e-Paper HAT 7.8inch e-Paper HAT 7.8inch HDMI e-Paper 7.5inch HD e-Paper HAT 7.5inch HD e-Paper HAT (B) 7.5inch e-Paper HAT 7.5inch e-Paper HAT (B) 7.5inch e-Paper HAT (C) 7.5inch e-Paper (G) 7.5inch NFC-Powered e-Paper 7.5inch NFC-Powered HD e-Paper 6inch e-Paper HAT 6inch HD e-Paper HAT 5.83inch e-Paper HAT 5.83inch e-Paper HAT (B) 5.83inch e-Paper HAT (C) 5.65inch e-Paper Module (F) 4.2inch e-Paper Cloud Module 4.2inch e-Paper Module 4.2inch e-Paper Module (B) 4.2inch e-Paper Module (C) 4.2inch NFC-Powered e-Paper 4.01inch e-Paper (F) 4.01inch e-Paper HAT (F) 3.7inch e-Paper 3.7inch e-Paper HAT 2.9inch e-Paper Module 2.9inch e-Paper Module (B) 2.9inch e-Paper Module (C) 2.9inch e-Paper HAT (D) 2.9inch Touch e-Paper HAT 2.9inch NFC-Powered e-Paper 2.7inch NFC-Powered e-Paper Module 2.7inch e-Paper HAT 2.7inch e-Paper HAT (B) 2.66.inch e-Paper 2.66inch e-Paper Module 2.66inch e-Paper (B) 2.66inch e-Paper Module (B) 2.13inch e-Paper Cloud Module 2.13inch e-Paper HAT 2.13inch e-Paper HAT (B) 2.13inch e-Paper HAT (C) 2.13inch e-Paper HAT (D) 2.13inch Touch e-Paper HAT 2.13inch NFC-Powered e-Paper 1.54inch NFC-Powered e-Paper (BB) 1.54inch NFC-Powered e-Paper (BW) 1.54inch e-Paper Module 1.54inch e-Paper Module (B) 1.54inch e-Paper Module (C) 1.02inch e-paper Module e-Paper Driver HAT EINK-DISP-103 E-Paper Shield e-Paper ESP8266 Driver Board E-Paper ESP32 Driver Board

7.8inch e-Paper is a big size screen, the glass panel and FPC is fragile, please be careful when using it for developing. we recommend you reinforce the FPC with scotch tape when developing. Please connect all the cables before powering the device, the device cannot support hot-plug.

There are two versions, one is a raw panel and another is a HAT version. Driver board (IT8951) is required for the raw panel, if you are the first time buying this e-paper, recommend you choose the HAT version which comes with the driver board.

Introduction

• 7.8-inch EPD (Electronic Paper Display) HAT for Raspberry Pi, 1872 x 1404 resolution, 16 gray scales, USB/SPI/I80/I2C interface.

• It has the advantages of low power consumption, wide viewing angle, and clear display under direct sunlight, and is often used in display applications such as shelf labels and industrial instruments.

More

Features

• No backlight, keeps displaying last content for a long time even when powered down.
• Low power consumption, basically power is only required for refreshing.
• Compatible with Raspberry Pi Zero/Zero W/Zero WH/2B/3B/3B+.
• USB/SPI/I80 interface, for connecting with host boards like Raspberry Pi/Nucleo, etc.
• Comes with development resources and manual (examples for Raspberry Pi/STM32).

Specifications

• Operating voltage: 5V
• Interface: USB/SPI/I80
• Outline dimension: 173.8mm × 127.6mm × 0.78mm
• Display size: 158.184mm × 118.638mm
• Dot pitch: 0.0845mm × 0.0845mm
• Resolution: 1872 × 1404
• Display color: black, white
• Grayscale: 2-16 (1-4 bit)
• Full refresh time: 450ms
• Total refresh power: 1.2W (typ.)
• Total standby power: 0.1W (typ.)
• Viewing angle: >170°

Working principle

This product is an E-paper device adopting the image display technology of Microencapsulated Electrophoretic Display, MED. The initial approach is to create tiny spheres, in which the charged color pigments are suspended in the transparent oil and would move depending on the electronic charge. The E-paper screen displays patterns by reflecting the ambient light, so it has no background light requirement. Under ambient light, the E-paper screen still has high visibility with a wide viewing angle of 180 degrees. It is the ideal choice for E-reading. (Note that the e-Paper cannot support updating directly under sunlight.)

How to use

Working with Windows PC

• Connect 7.8inch e-paper to IT8951 driver board as below:

• Connect the USB interface of the IT8951 driver board to PC.
• Download and open E-LINK-TCON-DEMO software.
• Click connect as below:

• Check option "AutoSet", then click "Open File" to open one picture for display. The browse diagram will be opened, and you should click "OK".

• Click "display" to refresh the picture.

Note: If you want to use the USB interface to develop the e-Paper on Windows, you need to contact the Waveshare team and sign the NDA before you can get the E-LINK-TCON-DEMO source code.
Note: Currently not available for individual users.

Working with Raspberry Pi

• Hardware connection

Insert IT8951 driver board to GPIO of Raspberry Pi, Connect e-Paper to the driver board.

You can also connect by wires.

Connect to Raspberry Pi via SPI

IT8951 Driver HAT	Raspberry Pi (BCM)	Description'
5V	5V	5V power input
GND	GND	Ground
MISO	P9	MISO Pin of SPI
MOSI	P10	MOSI Pin of SPI
SCK	P11	SCK Pin of SPI
CS	P8	Chip selection of SPI (Low active)
RST	P17	Reset pin (Low active)
HRDY	P24	Busy stats pin (Low when busy)

• Make sure you have switched the sail switch to SPI mode.

• Step 3: Install the BCM2835 C function library, open the Raspberry Pi terminal, and execute the following codes:

wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.60.tar.gz
tar zxvf bcm2835-1.60.tar.gz 
cd bcm2835-1.60/
sudo ./configure
sudo make
sudo make check
sudo make install
#Fore more, you can refer to: http://www.airspayce.com/mikem/bcm2835/

Finish.

• Step 4: Enable the SPI.

The Raspberry Pi adopts SPI to drive the IT8951 and the E-paper. Firstly, you need to enable the SPI as below:

Open the terminal command line and enter:

sudo raspi-config

And then execute: Interfacing Options -> P4 -> SPI -> Yes, as shown below:

• Step 5: Compile and execute the program:

Download and compile the demo, and run the following commands:

Method 1: Download from the official Waveshare website (recommended):

sudo apt-get install p7zip-full
sudo wget  https://files.waveshare.com/upload/8/80/IT8951_20200319_Release.7z
7z x IT8951_20200319_Release.7z -O./IT8951
cd IT8951/
sudo make clean
sudo make -j4

Method 2: Download from GitHub:

git clone https://github.com/waveshare/IT8951-ePaper.git
cd IT8951-ePaper/Raspberry
sudo make clean
sudo make -j4

• Check the VCOM value on the FPC

Add the VCOM value as a parameter and test the e-Paper, and this model is mode 0.

sudo ./epd -2.51 0

• Demo execution phenomenon:

1) First, the r-paper will refresh the 16 gray bars partially in sequence.

2) Then demonstrate the demo of drawing lines, circles, rectangles, characters, and numbers.

3) Then respectively demonstrate the demo of displaying BMP pictures in 1bp, 2bp, and 4bp modes.

4) Next, demonstrate the effect of fast refresh in A2 mode.

5) Then display a gif animation.

6) Then demonstrate a Demo that counts the frame rate.

7) Finally, the e-paper is whitened in Init mode for long-term storage.

Working with STM32

Driver Interface Selection

• Using the SPI to drive (recommended), the advantage is to occupy fewer pins, be easy to drive, and have a communication speed that can meet most of the scenarios.
• Using the I80 to drive (adopt this way if the SPI interface communication speed is not ideal), the advantage is that the drive method is relatively simple, communication speed is very fast, but occupy more pins.
• Using I2C to drive (not recommended due to its slow speed).

Driver Board Selection

As the IT8951 occupies most of the RAM space, some of the STM32 cannot support external SDRAM devices. So we here use Open429I as a test board, Open429I integrates IS42S16400J (64-MBIT) SDRAM, has full memory to drive the 7.8inch-e-Paper-HAT.

SPI

1) Hardware connection

Connect to STM32F429IGT6 (SPI)

IT8951	STM32	Description
5V	5V	5V Power input
GND	GND	Ground
MISO	PE13	Data output
MOSI	PE14	Data input
SCK	PE12	Clock input
CS	PE11	Chip select (Low active)
RST	PC5	Reset (Low for reset)
HRDY	PA7	BUSY state output (Low for busy)

2) Set the DIP switch to SPI mode

3) Download the demo code and test.

You can download the Demo code.

Open the project with Keil: Open429I-IT8951-Demo\Project\IT8951\MDK-ARM\Project.uvproj

Compile it, then open IT8951.h, and check if SPI mode is enabled. Compile it again and download to your board.

After downloading, the information will be printed as below (115200, 8N1)

I80

1） Hardware connection

Connect to STM32F429IGT6 (I80)

IT8951	STM32	Description
Vcc	5V	5V Power input
GND	GND	Ground
DBUS0~DBUS15	PB0~PB15	Data pins
HWE	PC1	Write enable (Low active)
D/C	PC7	Data/Command (Low for command)
CSEL	PC6	Chip select (Low active)
HRD	PC3	Read enable (Low for active)
RST	PC0	Reset (Low for reset)
BUSY	PA7	Busy state output (Low for busy)

2) Set the DIP switch to I80 mode

3) Display with demo code

You can download the Demo code

Open the project with Keil: Open429I-IT8951-Demo\Project\IT8951\MDK-ARM\Project.uvproj

Compile it, then open IT8951.h, and check if I80 mode is enabled. Compile it again and download it to your board.

Information is printed to the serial port as below (115200, 8N1)

Display pictures

For easy porting of our demo code, we display pictures with a data matrix instead of the file system.

We should first convert the BMP picture to a data matrix (arrays), and use it in demo code.

1) Prepare a BMP image, resize the picture to 800*600

2) Open BMP convert software, Click File->Open..-> to open the picture as below:

3) Click Image -> Convert to ->Gray256(8 BPP)

4) Click File ->Save As... ->Choose "C" bitmap file (*.c) -> input file name and click Save.

5) Choose 8 bits per pixel, and click OK. A C file will be saved to your PC

6) Add the C file to the Keil project, select unusable information

*********************************************************************
*                SEGGER Microcontroller GmbH & Co. KG                *
*        Solutions for real time microcontroller applications        *
*                           www.segger.com                           *
**********************************************************************
*                                                                    *
* C-file generated by                                                *
*                                                                    *
*        Bitmap Converter for emWin V5.22.                           *
*        Compiled Jul  4 2013, 12:18:24                              *
*        (c) 1998 - 2013 Segger Microcontroller GmbH && Co. KG       *
*                                                                    *
**********************************************************************
*                                                                    *
* Source file: zoo_800_600                                           *
* Dimensions:  800 * 600                                             *
* NumColors:   256                                                   *
*                                                                    *
**********************************************************************
*/
 
#include <stdlib.h>
 
#include "GUI.h"
 
#ifndef GUI_CONST_STORAGE
  #define GUI_CONST_STORAGE const
#endif
 
extern GUI_CONST_STORAGE GUI_BITMAP bmzoo_800_600;
 
/*********************************************************************
*
*       Palette
*
*  Description
*    The following are the entries of the palette table.
*    The entries are stored as a 32-bit value of which 24 bits are
*    actually used according to the following bit mask: 0xBBGGRR
*
*    The lower   8 bits represent the Red component.
*    The middle  8 bits represent the Green component.
*    The highest 8 bits represent the Blue component.
*/
static GUI_CONST_STORAGE GUI_COLOR _Colorszoo_800_600[] = {
  0x000000, 0x010101, 0x020202, 0x030303,
  0x040404, 0x050505, 0x060606, 0x070707,
  0x080808, 0x090909, 0x0A0A0A, 0x0B0B0B,
  0x0C0C0C, 0x0D0D0D, 0x0E0E0E, 0x0F0F0F,
  0x101010, 0x111111, 0x121212, 0x131313,
  0x141414, 0x151515, 0x161616, 0x171717,
  0x181818, 0x191919, 0x1A1A1A, 0x1B1B1B,
  0x1C1C1C, 0x1D1D1D, 0x1E1E1E, 0x1F1F1F,
  0x202020, 0x212121, 0x222222, 0x232323,
  0x242424, 0x252525, 0x262626, 0x272727,
  0x282828, 0x292929, 0x2A2A2A, 0x2B2B2B,
  0x2C2C2C, 0x2D2D2D, 0x2E2E2E, 0x2F2F2F,
  0x303030, 0x313131, 0x323232, 0x333333,
  0x343434, 0x353535, 0x363636, 0x373737,
  0x383838, 0x393939, 0x3A3A3A, 0x3B3B3B,
  0x3C3C3C, 0x3D3D3D, 0x3E3E3E, 0x3F3F3F,
  0x404040, 0x414141, 0x424242, 0x434343,
  0x444444, 0x454545, 0x464646, 0x474747,
  0x484848, 0x494949, 0x4A4A4A, 0x4B4B4B,
  0x4C4C4C, 0x4D4D4D, 0x4E4E4E, 0x4F4F4F,
  0x505050, 0x515151, 0x525252, 0x535353,
  0x545454, 0x555555, 0x565656, 0x575757,
  0x585858, 0x595959, 0x5A5A5A, 0x5B5B5B,
  0x5C5C5C, 0x5D5D5D, 0x5E5E5E, 0x5F5F5F,
  0x606060, 0x616161, 0x626262, 0x636363,
  0x646464, 0x656565, 0x666666, 0x676767,
  0x686868, 0x696969, 0x6A6A6A, 0x6B6B6B,
  0x6C6C6C, 0x6D6D6D, 0x6E6E6E, 0x6F6F6F,
  0x707070, 0x717171, 0x727272, 0x737373,
  0x747474, 0x757575, 0x767676, 0x777777,
  0x787878, 0x797979, 0x7A7A7A, 0x7B7B7B,
  0x7C7C7C, 0x7D7D7D, 0x7E7E7E, 0x7F7F7F,
  0x808080, 0x818181, 0x828282, 0x838383,
  0x848484, 0x858585, 0x868686, 0x878787,
  0x888888, 0x898989, 0x8A8A8A, 0x8B8B8B,
  0x8C8C8C, 0x8D8D8D, 0x8E8E8E, 0x8F8F8F,
  0x909090, 0x919191, 0x929292, 0x939393,
  0x949494, 0x959595, 0x969696, 0x979797,
  0x989898, 0x999999, 0x9A9A9A, 0x9B9B9B,
  0x9C9C9C, 0x9D9D9D, 0x9E9E9E, 0x9F9F9F,
  0xA0A0A0, 0xA1A1A1, 0xA2A2A2, 0xA3A3A3,
  0xA4A4A4, 0xA5A5A5, 0xA6A6A6, 0xA7A7A7,
  0xA8A8A8, 0xA9A9A9, 0xAAAAAA, 0xABABAB,
  0xACACAC, 0xADADAD, 0xAEAEAE, 0xAFAFAF,
  0xB0B0B0, 0xB1B1B1, 0xB2B2B2, 0xB3B3B3,
  0xB4B4B4, 0xB5B5B5, 0xB6B6B6, 0xB7B7B7,
  0xB8B8B8, 0xB9B9B9, 0xBABABA, 0xBBBBBB,
  0xBCBCBC, 0xBDBDBD, 0xBEBEBE, 0xBFBFBF,
  0xC0C0C0, 0xC1C1C1, 0xC2C2C2, 0xC3C3C3,
  0xC4C4C4, 0xC5C5C5, 0xC6C6C6, 0xC7C7C7,
  0xC8C8C8, 0xC9C9C9, 0xCACACA, 0xCBCBCB,
  0xCCCCCC, 0xCDCDCD, 0xCECECE, 0xCFCFCF,
  0xD0D0D0, 0xD1D1D1, 0xD2D2D2, 0xD3D3D3,
  0xD4D4D4, 0xD5D5D5, 0xD6D6D6, 0xD7D7D7,
  0xD8D8D8, 0xD9D9D9, 0xDADADA, 0xDBDBDB,
  0xDCDCDC, 0xDDDDDD, 0xDEDEDE, 0xDFDFDF,
  0xE0E0E0, 0xE1E1E1, 0xE2E2E2, 0xE3E3E3,
  0xE4E4E4, 0xE5E5E5, 0xE6E6E6, 0xE7E7E7,
  0xE8E8E8, 0xE9E9E9, 0xEAEAEA, 0xEBEBEB,
  0xECECEC, 0xEDEDED, 0xEEEEEE, 0xEFEFEF,
  0xF0F0F0, 0xF1F1F1, 0xF2F2F2, 0xF3F3F3,
  0xF4F4F4, 0xF5F5F5, 0xF6F6F6, 0xF7F7F7,
  0xF8F8F8, 0xF9F9F9, 0xFAFAFA, 0xFBFBFB,
  0xFCFCFC, 0xFDFDFD, 0xFEFEFE, 0xFFFFFF
};
 
static GUI_CONST_STORAGE GUI_LOGPALETTE _Palzoo_800_600 = {
  256,  // Number of entries
  0,    // No transparency
  &_Colorszoo_800_600[0]
};
 
GUI_CONST_STORAGE GUI_BITMAP bmzoo_800_600 = {
  800, // xSize
  600, // ySize
  800, // BytesPerLine
  8, // BitsPerPixel
  _aczoo_800_600,  // Pointer to picture data (indices)
  &_Palzoo_800_600   // Pointer to palette
};

7) Modify the codes

static GUI_CONST_STORAGE unsigned char _aczoo_800_600[] = {

to this one. (You can change the name of the array to the one you like)

const unsigned char zoo_800_600[] = {

8) Modify related codes in IT8951.C as below

extern const unsigned char zoo_800_600[];
void IT8951DisplayExample3()
{
	IT8951LdImgInfo stLdImgInfo;
	IT8951AreaImgInfo stAreaImgInfo;
	TWord width = gstI80DevInfo.usPanelW;
	TWord high = gstI80DevInfo.usPanelH;
	TDWord i;
 
	for (i = 0;i < width*high;i++)
	{
		gpFrameBuf[i] = zoo_800_600[i];
	}
 
	IT8951WaitForDisplayReady();
 
	//Setting Load image information
	stLdImgInfo.ulStartFBAddr    = (TDWord)gpFrameBuf;
	stLdImgInfo.usEndianType     = IT8951_LDIMG_L_ENDIAN;
	stLdImgInfo.usPixelFormat    = IT8951_8BPP; 
	stLdImgInfo.usRotate         = IT8951_ROTATE_0;
	stLdImgInfo.ulImgBufBaseAddr = gulImgBufAddr;
	//Set Load Area
	stAreaImgInfo.usX      = 0;
	stAreaImgInfo.usY      = 0;
	stAreaImgInfo.usWidth  = width;
	stAreaImgInfo.usHeight = high;
 
	IT8951HostAreaPackedPixelWrite(&stLdImgInfo, &stAreaImgInfo);//Display function 2
	IT8951DisplayArea(0,0, gstI80DevInfo.usPanelW, gstI80DevInfo.usPanelH, 2);
}

【Note】Guides provided here are all about how to use the 10.3inch e-Paper HAT (D). If you have any questions about how to modify and develop your own codes, please refer to resources of IT8951 #Resources

Note

Hardware Connection

Due to product upgrades, the hardware connections of the different E-paper HATs may be different compared to the picture, the specific FPC cable and pin numbers shall prevail:

• Check example 1:

• Check example 2:

DIP Switch

• At present, it is not recommended to drive via the I2C interface, it is recommended to use the USB, I80, or SPI interface to drive.
• Whether to drive via the USB interface, I80 interface, or SPI interface, you need to turn the DIP switch circled in red in the figure below to the right ON position, as shown in the figure below:

• If the E-LINK-TCON-DEMO cannot recognize the IT8951 when connected to a PC by USB, please check whether both sides of the two dip switches marked by the red box are on, only when both dipswitches marked by the red box are on can the PC recognize it.

Choose SPI or I80 to Drive

• If you use a USB driver, you do not need to pay attention to the dip switch in the green box shown below:
• If you use the SPI driver or I80 driver, you need to pay attention to the dip switch in the green box shown below, if you dial to I80 side, it means to use the I80 driver, if you dial to SPI side, it means use SPI driver:

Demo Description

New Features

• 1. Using 4bpp to refresh 16 levels of grayscale images, the amount of data transferred by SPI is reduced to half of the original, avoiding the waste of RAM and transfer time caused by using 8bpp to refresh 16 levels of grayscale images in the previous version.
• 2. SPI transfer speed doubled, effective in Raspberry Pi 3 generation, Raspberry Pi 4 generation is not effective due to the increase of CPU main frequency.
• 3. The time interval for refreshing pictures is reduced to 1/4 of the original one. It takes about 10S to refresh a 16-level grayscale BMP picture to 10.3-inch e-Paper (D) using GC16 mode in the previous version of the program, but only about 3S in this demo.
• 4. Avoid the memory leak caused by the allocation of cache after opening the bmp file in the previous version but not released.
• 5. Add 1bpp, 2bpp, 4bpp, 8bpp mode support.
• 6. Add the A2 mode refresh demo, you can feel the A2 mode refresh speed.
• 7. Add support for drawing points, lines, circles, rectangles, writing characters, etc. Support grayscale selection of drawing characters and patterns, support 1bpp, 2bpp, 4bpp, 8bpp, if you choose 1bpp, also support A2 mode refresh.
• 8. Add 1bpp, 2bpp, 4bpp, and 8bpp refresh support for bmp pictures, if you choose 1bpp, also support A2 mode refresh.
• 9. Add the demo of displaying GIF pictures, which can write multiple pictures to IT8951 cache, and then directly refresh the data in the cache to the ink screen when displaying, eliminating the data transfer process between RPi and IT8951, and refreshing the frame rate up to 7fps.
• 10. Add frame rate test demos to test the frame rate when refreshing different size areas, 1bpp, 2bpp, 4bpp, 8bpp, A2 mode, and GC16 mode.
• 11. Support enhanced drive capability to avoid partial blurring of the screen display in some cases.
• 12. Support 4-byte alignment for 6-inch ePaper HAT and 6-inch HD ePaper HAT to avoid abnormal display when 1bpp is refreshed.
• 13. Demos need to enter VCOM when running, and the end of the routine will be fully painted white to protect the screen and extend the life of the screen.
• 14. Optimize the program structure, reduce the coupling of the program, standardize some functions, and variable naming.

Demo Description

Refresh 16 Grayscale Bars with Light to Dark Gray Levels in Sequence

• Function name: DisplayColorPaletteExample
• This demo shows how to use 4bp, combined with GC16 mode, to partially refresh 16 grayscale bars from light to dark in sequence.

Draw Points, Lines, Circles, Rectangles and Characters

• Function name: DisplayCharacterPatternExample
• The demo demonstrates, how to draw points, lines, circles, rectangles, and write characters, supports 1bpp, 2bpp, 4bpp, and 8bpp, and if 1bpp is used, it also supports A2 mode refresh.

Display BMP Pictures

• Function name: DisplayBMPExample
• The demo demonstrates how to refresh a bmp image, supporting 1bpp, 2bpp, 4bpp, and 8bpp, and if 1bpp is used, A2 mode refresh is also supported.

A2 Mode Refresh Example

• Function name: DynamicRefreshExample
• This demo demonstrates how to use A2 mode for refreshing. In this demo, it will be refreshed several times, the refresh area will keep changing, and the area of the refresh area will gradually become larger, and after several times of refreshing, the residual shadow will appear, and INIT mode will be used to clear the residual shadow. With this demo, you can feel the refresh speed of the A2 mode.

Display GIF Pictures

• Function name: DynamicGIFExample
• The demo demonstrates how to refresh a GIF image. In this demo, a GIF image is split into 7 bmp images beforehand, and the 7 bmp images are written to the cache of the IT8951 in succession, and when displaying, the image data is read out from the cache of the IT8951 at the corresponding address and refreshed to the E-paper display.

Frame Rate Test

• Function name: CheckFrameRateExample
• This demo is designed to facilitate testing: the frame rate of refresh when refreshing different size areas, 1bpp, 2bpp, 4bpp, 8bpp, and A2 mode, GC16 mode, in this demo, the time to refresh 10 frames of images will be counted automatically and the frame rate (fps) will be calculated automatically.

Related Description

Mode Description

IT8951 for different resolutions of the screen brushed into different firmware, different firmware has different refresh modes, see E-paper-mode-declaration for details, the modes used in the demo are INIT mode, GC16 mode, and A2 mode.

The following is a brief description of the relevant modes:

Mode	Features	6inch/6inch HD	7.8inch/9.7inch/10.3inch
INIT	Used to erase the display content, and clear the screen. It is recommended to use INIT mode to clear the screen after several A2 mode refreshes	Mode0	Mode0
GC16	Adopt 16 levels of grayscale to update the screen display content, the best display effect	Mode2	Mode2
A2	Only black and white can be refreshed, but the refresh speed is the fastest	Mode4	Mode6

//basic mode definition
UBYTE INIT_Mode = 0;
UBYTE GC16_Mode = 2;
//A2_Mode's value is not fixed, is decided by the firmware's LUT 
UBYTE A2_Mode = 6;

if( strcmp(LUT_Version, "M641") == 0 ){
    //6inch e-Paper HAT(800,600), 6inch HD e-Paper HAT(1448,1072), 6inch HD touch e-Paper HAT(1448,1072)
    A2_Mode = 4;
    Four_Byte_Align = true;
}else if( strcmp(LUT_Version, "M841") == 0 ){
    //9.7inch e-Paper HAT(1200,825)
    A2_Mode = 6;
}else if( strcmp(LUT_Version, "M841_TFA2812") == 0 ){
    //7.8inch e-Paper HAT(1872,1404)
    A2_Mode = 6;
}else if( strcmp(LUT_Version, "M841_TFA5210") == 0 ){
    //10.3inch e-Paper HAT(1872,1404)
    A2_Mode = 6;
}else{
    //default set to 6 as A2 Mode
    A2_Mode = 6;
}

BPP Description

BPP (Bits Per Pixel), which indicates the number of bits occupied by a pixel, currently, all screens support 1bpp, 2bpp, 4bpp, 8bpp mode refresh.

• 1bpp
• Each pixel occupies 1 bit.
• Can display 2(2^1=2) levels of grayscale, suitable for A2 mode (can only update 2 levels of grayscale in black and white)
• Each byte can store 8-pixel points.
• Pixel points are stored in 1 byte in RAM in large end order:

• In IT8951 default use a small end sequence, need to convert the big end sequence to small end sequence.
• 2bpp
• Each pixel occupies 2 bits.
• Capable of displaying 4(2^2=4) levels of grayscale.
• Each byte can store 4-pixel points.
• Pixel points are stored in RAM in large end order per 1 byte:

• In IT8951 default use a small end sequence, need to convert the big end sequence to a small end sequence.
• 4bpp
• Each pixel occupies 4 bits.
• Capable of displaying 16(2^4=16) levels of grayscale.
• Each byte can store 2-pixel points.
• Pixel points are stored in RAM in large end order for each 1 byte:

• In IT8951 default uses small end order, need to convert the big end order to small end order.
• It is recommended to use 4bpp for a refreshing, which can display 16 levels of grayscale, and compared to 8bpp, the amount of transmitted data is reduced by half, the transmission speed is twice as fast, and there is no difference in display effect.
• 8bpp
• Each pixel occupies 8 bits.
• Can display 256 (2^8=256) levels of grayscale, but in IT8951 only the high 4 bits are taken, so only 16 levels of grayscale can be displayed.
• Each byte can store 1 pixel.
• Pixel points are stored in RAM in large end order per 1 byte:

• In IT8951, the small end order is used by default, and it is necessary to convert the big end order to the small end order
• To get the corresponding grayscale image from the original image In the program, the specific operation is: whether drawing points, drawing lines, or getting the image, each pixel point obtained is 1 byte (8 bits), if you want to get the corresponding grayscale, you only need to get the corresponding high bit of the byte. For example, if you want to get 2bpp pixel points, you only need to get the high 2 bits from 8bpp (8 bits). The specific operation is shown in the following program, in which each byte in RAM is also converted from big-endian to little-endian.

UDOUBLE Addr = X * (Paint.BitsPerPixel) / 8 + Y * Paint.WidthByte;
switch( Paint.BitsPerPixel ){
    case 8:{
        Paint.Image[Addr] = Color & 0xF0;
        break;
    }
    case 4:{
        Paint.Image[Addr] &= ~( (0xF0) >> (7 - (X*4+3)%8 ) );
        Paint.Image[Addr] |= (Color & 0xF0) >> (7 - (X*4+3)%8 );
        break;
    }
    case 2:{
        Paint.Image[Addr] &= ~( (0xC0) >> (7 - (X*2+1)%8 ) );
        Paint.Image[Addr] |= (Color & 0xC0) >> (7 - (X*2+1)%8 );
        break;
    }
    case 1:{
        Paint.Image[Addr] &= ~( (0x80) >> (7 - X%8) );
        Paint.Image[Addr] |= (Color & 0x80) >> (7 - X%8);
        break;
    }
}

4-byte Alignment Description

In the actual test, we found that for 6inch e-Paper HAT, 6inch HD e-Paper HAT, and 6inch HD touch e-Paper HAT, when using 1bpp mode refresh, the starting point X and refresh width W of the refresh area need to be aligned with 4 bytes (32bit), otherwise, the image of the refresh area will be displayed abnormally, as shown in the following procedure:

if( strcmp(LUT_Version, "M641") == 0 ){
    //6inch e-Paper HAT(800,600), 6inch HD e-Paper HAT(1448,1072), 6inch HD touch e-Paper HAT(1448,1072)
    A2_Mode = 4;
    Four_Byte_Align = true;
}else if( strcmp(LUT_Version, "M841") == 0 ){
...
}

if(Four_Byte_Align == true){
    In_4bp_Refresh_Area_Width = Panel_Width - (Panel_Width % 32);
}else{
    In_4bp_Refresh_Area_Width = Panel_Width;
}

X_Start = Min_X < 32 ? 0 : Min_X - (Min_X % 32);
Debug("X_Start:%d\r\n",X_Start);
X_End = ( Max_X + (32 - (Max_X % 32)) ) > Touch_Pannel_Area_Width ? ( Max_X - (Max_X % 32) )  : ( Max_X + (32 - (Max_X % 32)) );
Debug("X_End:%d\r\n",X_End);
Y_Start = Min_Y;
Debug("Y_Start:%d\r\n",Y_Start);
Y_End = Max_Y;
Debug("Y_Start:%d\r\n",Y_End);
Width = X_End - X_Start;
if(Width<=0){
    Width = 32;
}
Debug("Width:%d\r\n",Width);
Height = Y_End-Y_Start;
if(Height<=0){
    Height = 32;
}
Debug("Height:%d\r\n",Height);

SPI Transfer Speed Description

Due to the difference in CPU main frequency of Raspberry Pi 3 and Raspberry Pi 4:

• Raspberry Pi 3 can still transmit normally when it adopts 16 division frequency, and the fastest can only adopt 16 division frequency.
• While Raspberry Pi 4B adopts 16 divisions, the SPI rate is too high, and there will be transmission errors, so the SPI of Raspberry Pi 4B can only use 32 divisions at the fastest.
• BCM2835 library manual, different Raspberry Pi version, different clock frequency, the corresponding frequency description is shown below:

• If you need to obtain the most suitable SPI transfer speed, you need to select a different SPI clock division according to your Raspberry Pi version, as shown in the following program and its comments:

bcm2835_spi_begin();//Start spi interface, set spi pin for the reuse function
bcm2835_spi_setBitOrder(BCM2835_SPI_BIT_ORDER_MSBFIRST);//High first transmission
bcm2835_spi_setDataMode(BCM2835_SPI_MODE0);//spi mode 0

//bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_16);//For RPi 3/3B/3B+
bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_32);//For RPi 4B

/* SPI clock reference link：*/
/*http://www.airspayce.com/mikem/bcm2835/group__constants.html#gaf2e0ca069b8caef24602a02e8a00884e*/

Enhance Driving Ability

In some cases, due to the FPC line being too long and other reasons, will lead to the ink screen display partial blur, at this time, trying to enhance the drive capability, can effectively solve the problem of the blurred screen display.
Specific procedures are shown below:

#if(Enhance)
    Debug("Attention! Enhanced driving ability, only used when the screen is blurred\r\n");
    Enhance_Driving_Capability();
#endif

/******************************************************************************
function:  Enhanced driving capability
parameter:  Enhanced driving capability for IT8951, in case the blurred display effect
******************************************************************************/
void Enhance_Driving_Capability(void)
{
    UWORD RegValue = EPD_IT8951_ReadReg(0x0038);
    Debug("The reg value before writing is %x\r\n", RegValue);
    EPD_IT8951_WriteReg(0x0038, 0x0602);
    RegValue = EPD_IT8951_ReadReg(0x0038);
    Debug("The reg value after writing is %x\r\n", RegValue);
}

If the E-LINK-TCON-DEMO software is used on a PC (Windows) to refresh the E-paper via the USB interface, the drive can be enhanced by modifying the register values as follows:

• Step 1: Read the data of the registered address 0x18000038.

If the data of the read register address 0x18000038 is 0x02, it means that the driver is not yet enhanced.

• Step 2: Modify the data of register address 0x18000038.

Modify the data of register address 0x18000038 to 602 to enhance the driving capability.

• Step 3: Check the data of register address 0x18000038.

Check whether the data of register address 0x18000038 is modified successfully. If the data of this address is 0x602, it means that the driving capability has been enhanced and the screen can be brushed in this state to avoid the blurred display in some cases, such as the FPC line is too long and the production batch is different.

Use Correct VCOM Value

The VCOM value of each E-paper has certain differences. The VCOM value of each E-paper is marked on the FPC cable, so make sure the correct VCOM value is used in each execution of the demo, otherwise, the display will become worse if the E-paper works under the wrong VCOM value for a long time.

Development Description

The above only illustrates how to use the 7.8-inch e-Paper HAT (D). For details on how to modify and perform secondary development, users need to consult the relevant code by themselves.

Please refer to the IT8951 information provided in the Resource.

Resources

Schematic

• Schematic of IT8951 Driver Board
• Schematic of 7.8inch e-Paper Adapter board

Demo code

• Demo code for Raspberry Pi
• Demo code for STM32 (Open429I)
• Github

Third Parties Examples

• Inkycal Project

This is the Inkycal project for reference.

Datasheet

• 7.8inch e-Paper Specification
• IT8951 Specifications

Other documents

• IT8951 I80/SPi/I2C Programming Guide
• IT851 USB Programming Guide
• Mode description

Software

• E-LINK-TCON-DEMO
• Zimo221.7z
• Picture Modulo

FAQ

Questions About Software & Hardware

Question:Why can't I refresh the picture with E-LINK-TCON-DEMO? How can I check if the wiring is correct?

 Answer:

The most likely reason for not being able to print the picture is that the wires are not connected correctly. Please check the wiring. Due to the different batches of products, the wiring method may not be exactly the same as the picture. Please refer to the cable and 1 and 40 on the silk screen. As shown in the red line in the figure below:

{{{3}}}

{{{4}}}

{{{5}}}

Question:Connect the PC, open the host computer, click connect, and it will prompt Open IT8951 Device Fail. What is the problem?

 Answer:

1. Replace the Micro USB cable with good quality. There are many USB cables on the market that have too much voltage drop, which will cause the USB interface to fail to enumerate normally.

2. Try changing the USB interface. It is recommended to use the USB interface on the back of the PC. Relatively speaking, the power supply current will be larger.
3. Turn the DIP switch to the end. During shipping, the DIP switches may be loosened, and the floating configuration pins cannot put the IT8951 into USB mode.

{{{3}}}

{{{4}}}

{{{5}}}

Question:Click connect, and the host computer prompts that it is normal. But point refresh doesn't respond?

 Answer:

Click connect. The following information will be displayed normally (different models will display different information):

If you fail to refresh, check whether the hard link is normal, use the USB port on the back of the PC (most of the USB ports on the front of the PC have weak power supply capability), and replace the e-paper test. Note: Do not plug and unplug the e-paper with power on, otherwise the driver board and e-paper may be damaged.

{{{3}}}

{{{4}}}

{{{5}}}

Questions About Screen

Question:What is the usage environment of the e-ink screen?

 Answer:

• 【Operating condition】Temperature range: 0~50°C; Humidity range: 35%~65%RH
• 【Storage condition】Temperature range: below 30°C; Humidity range: below 55%RH; Maximum storage time: 6 months
• 【Transportation condition】Temperature range:-25~70°C; Maximum shipping time: 10 days
• 【After unpacking】Temperature range: 20°C±5°C; Humidity range: 50±5%RH; Maximum storage time: Assembled within 72 hours

{{{5}}}

Question:E-ink screen refresh precautions

 Answer:

• Refresh mode:
  • Full refresh: The e-ink screen will flicker several times during refreshing (the flicking times depends on the refresh time), and the flicker is to remove the ghosting to achieve the best display effect.
  • Partial refresh: The e-ink screen has no flickering effect during refreshing. Users who use partial flashing should pay attention to performing a full flashing operation to remove the ghosting after refreshing several times, otherwise, the ghosting problem will become more and more serious, or even damage the screen. (At present, only some black and white e-ink screens support local brushing, please refer to the product page for details).
• Refresh frequency:
  • During use, it is recommended that customers set the refresh interval of the e-ink screen to at least 180 seconds. (Except for products that support the partial refreshing function)
  • During the standby process (that is, after the refresh operation), it is recommended that the customer set the e-ink screen to sleep mode, or power off (the power supply part of the ink screen can be disconnected with an analog switch) to reduce power consumption and prolong the life of the e-ink screen. (If some e-ink screens are powered on for a long time, the screen will be damaged beyond repair.)
  • During the use of the e-ink screen, it is recommended that customers update the display screen at least every 24 hours. (If the screen keeps the same picture for a long time, there will be a burn-in situation that is difficult to repair).
• Application scenarios:
  • The e-ink screen is recommended for indoor use. If it is used outdoors, it is necessary to prevent the e-ink screen from being exposed to direct sunlight, and at the same time, it is necessary to take ultraviolet protection measures, because charged particles will dry out under strong light for a long time, resulting in loss of activity and failure to refresh. This situation is irreversible. When designing electronic ink screen products, customers should pay attention to determine whether the use environment meets the requirements of electronic ink screens.

{{{5}}}

Question:What is the refresh rate/lifetime of the e-ink screen?

 Answer:

Ideally, with normal use, it can be refreshed 1,000,000 times (1 million times).

{{{5}}}

Question:After a period of use, the screen refresh (full refresh) has a serious afterimage problem that cannot be repaired?

 Answer:

Power on the development board for a long time, after each refresh operation, it is recommended to set the screen to sleep mode or directly power off the processing, otherwise, the screen may burn out when the screen is in a high voltage state for a long time.

{{{5}}}

Question:After the ink screen enters deep sleep mode, can it be refreshed again?

 Answer:

Yes, but you need to re-initialize the electronic paper with software.

{{{5}}}

Question:Is bare screen shipped with a surface coating?

 Answer:

Yes.

{{{5}}}

Support

Technical Support

If you need technical support or have any feedback/review, please click the Submit Now button to submit a ticket, Our support team will check and reply to you within 1 to 2 working days. Please be patient as we make every effort to help you to resolve the issue.
Working Time: 9 AM - 6 AM GMT+8 (Monday to Friday)

Submit Now