From Waveshare Wiki
Jump to: navigation, search
(4 intermediate revisions by 2 users not shown)
Line 1: Line 1:
{{Infobox item
|name=7.5inch e-Paper (B)
|name2=7.5inch e-Paper HAT (B)
|img=[[File:7.5inch-e-Paper-B-1.jpg|300px|{{Amazon_nolink|default={{#ifeq: {{#urlget:amazon|0}}|{{#urlget:Amazon|0}}| default|}}|url=link=}}]]
|img2=[[File:7.5inch-e-paper-hat-b-4.jpg|300px|{{Amazon_nolink|default={{#ifeq: {{#urlget:amazon|0}}|{{#urlget:Amazon|0}}| default|}}|url=link=}}]]
|caption=800x480, 7.5inch EPD panel
|caption2=800x480, 7.5inch EPD HAT for Raspberry Pi, three-color, SPI interface
|category=[[:Category:OLEDs / LCDs|OLEDs / LCDs]], [[:Category:LCD|LCD]]
|{{#ifeq: {{#urlget:amazon|0}}|{{#urlget:Amazon|0}}| default|}}=display
|website_cn=[ 官方中文站点]
|website_en=[ Waveshare website]
{{Product List|OLEDs / LCDs/e-Paper}}
<div class="tabber">
<div class="tabbertab" title="Introduction">
= Introduction =
{{E-Paper Raw Panel}}
800x480, 7.5inch EPD (Electronic Paper Display) HAT for Raspberry Pi, three-color, SPI interface
<font color="#FF0000">【Version update instructions】:
*V3 version: Currently shipped version with the same resolution as V2 version, compatible with hardware, software needs to be updated (using V2 routines, routines compatible with V2 and V3 versions, December 2020)
*V2 version: Higher resolution, 800x480 resolution support (V1 version resolution is 640x384), V2 version hardware structure and interface compatible with V1 version, but the software needs to be updated (using V2 routines)
{{Amazon|{{#ifeq: {{#urlget:amazon|0}}|{{#urlget:Amazon|0}}| default|}}=display
|More = [ More]}}
*Dimension: 7.5inch
*Outline dimension (raw panel): 170.2mm x 111.2mm x 1.18mm
*Outline dimension (Driver board):65mm x 30.2mm
*Display dimension:163.2mm x 97.92mm
*Operating voltage:3.3V/5V
*Communication interface:SPI
*Pixel pitch:0.205x 0.204(old version:0.255x0.255)
*Resolution:800 x 480(old version:640x384)
*Display color:Black/White/Red
*Grey level: 2
*Full Refresh Time:16s
*Refresh power:48mW(typ.)
*Standby current: <0.01uA (almost none)
1.Refresh time: The refresh time is the experimental results, the actual refresh time will have errors, and the actual effect shall prevail. There will be a flickering effect during the global refresh process, this is a normal phenomenon
2. Power consumption: The power consumption data is the experimental results. The actual power consumption will have a certain error due to the existence of the driver board and the actual use situation. The actual effect shall prevail.
==SPI Communication Timing==
Since the ink screen only needs to be displayed, the data cable (MISO) sent from the machine and received by the host is hidden here.
*CS: Slave chip select, when CS is low, the chip is enabled
*DC: data/command control pin, write command when DC=0; write data when DC=1
*SCLK: SPI communication clock
*SDIN: SPI communication master sends, slave receives
*Timing: CPHL=0, CPOL=0 (SPI0)
[Remarks] For specific information about SPI, you can search for information online.<big>
==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 display 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''')
===Pixel & Byte===
We define the pixels in a monochrome picture, 0 is black and 1 is white.<br />
White:□: Bit 1<br />
Black:■: Bit 0<br />
*The dot in the figure is called a pixel. As we know, 1 and 0 are used to define the color, therefore we can use one bit to define the color of one pixel, and 1 byte = 8pixels<br />
*For example, If we set the first 8 pixels to black and the last 8 pixels to white, we show it by codes, they will be 16 bit as below:<br />
[[file:e-paper_hardware_work_1.png]]<br />
For computer, the data is saved in MSB format:<br />
[[file:e-paper_hardware_work_2.png]]<br />
So we can use two bytes for 16 pixels.<br />
Black and white processing and three-color processing of 7.5inch e-paper V1
Because of the problem of the controller, it defines 0000b to indicate that the corresponding pixel is black, and 0011b to indicate that the corresponding pixel is white, which is 4bit = 1pixel, and the lower two bits of the 4bit are both 0 to display black. On the contrary, the lowest two bits of 4bit can be 1 at the same time. Display white, other data will cause the color of the pixel to be uncertain;
0x00: 2 pixels ■■
0x03: 2 pixels ■□
0x30: 2 pixels □■
0x33: 2 pixels
Taking 4 pixels as an example, we assume that the first 2 pixels are black and the last 2 pixels are white, then the logic of people is like this, which is stored in sequence:
For a computer, its data storage method is high-order first, low-order last, and a byte has only 8 bits, so it is stored in a byte like this:
As explained earlier, other three-color screens are controlled by 2 registers, and this one is controlled by only 1 register. It still needs to transmit two pictures, one black and white and one red and white, and then the display will superimpose the two pictures.
The above explains the black and white processing of 5.83-inch and 7.5-inch. If you are careful, you will find why the upper two bits of 4bit are not used. We use these two bits to represent red or yellow.
Then we use two digits to represent:<br />
00b: white<br />
01b: red<br />
The upper two digits represent red, and the lower two digits represent black. If the dot is red, black will not be displayed, and the value of the lower two digits will be ignored, so the ink screen has the following definitions:
0000b: black, the actual value is 0x0<br />
0100b: red, the actual value is 0x4<br />
0111b: red, the actual value is 0x4<br />
0011b: white, the actual value is 0x3<br />
The processing of a monochrome image is to save 1 pixel in 1bit, so 8 points of color are stored in one byte, but the above processing does 4bit represent a pixel:
In order to facilitate understanding, assuming that there are 8 pixels, then displaying 8 pixels requires 8 pixels in red and white and 8 pixels in black and white, because 1 point is superimposed by two pixels, 8 Pixels are stored in 1 byte, and red and white and black and white occupy two bytes each. A 1 in a red-and-white picture indicates red, a 0 indicates white, a 0 in a black-and-white picture indicates black, and a 1 indicates white.<br />
If we specify that white is stored as 1 and red or black is stored as 0, then we have the following representation:<br />
<div style="background-color: #343434;text-align: center;color: white;padding: 20px;margin: 8px;">
=7.5inch e-Paper HAT (B) Manual=
And 1 byte of black and white part controls 8 pixels, and 1 byte of red and white part controls 8 pixels, then it can be expressed as follows:<br />
#For the screen that supports partial update, please note that you cannot refresh the screen with the partial mode all the time. After several partial updating, you need to fully refresh the screen once. Otherwise, the screen display effect will be abnormal, which cannot be repaired!<br/>
#Because of the different batches, some of them have aberrations. Store the e-Paper right side up will reduce it. And if the e-Paper didn't be refreshed for a long time, it will become more and more reddish/yellowish. Please use the demo code to refresh the e-paper several times in this case.<br/>
#Note that the screen cannot be powered on for a long time. When the screen is not refreshed, please set the screen to sleep mode, or power off the e-Paper. Otherwise, the screen will remain in a high voltage state for a long time, which will damage the e-Paper and cannot be repaired!<br/>
#When using the e-Paper, it is recommended that the refresh interval be at least 180s, and refresh at least once every 24 hours. If the e-Paper is not used for a long time, the ink screen should be brushed and stored. (Refer to the datasheet for specific storage environment requirements)<br/>
#After the screen enters sleep mode, the sent image data will be ignored, and it can be refreshed normally only after initializing again.<br/>
#Control the 0x3C or 0x50 (refer to the datasheet for details) register to adjust the border color. In the routine, you can adjust the Border Waveform Control register or VCOM AND DATA INTERVAL SETTING to set the border.<br/>
#If you find that the created image data is displayed incorrectly on the screen, it is recommended to check whether the image size setting is correct, change the width and height settings of the image and try again.<br/>
#The working voltage of the e-Paper is 3.3V. If you buy the raw panel and you need to add a level convert circuit for compatibility with 5V voltage. The new version of the driver board (V2.1 and subsequent versions) has added a level processing circuit, which can support both 3.3V and 5V working environments. The old version can only support a 3.3V working environment. You can confirm the version before using it. (The one with the 20-pin chip on the PCB is generally the new version)<br/>
#The FPC cable of the screen is relatively fragile, pay attention to bending the cable along the horizontal direction of the screen when using it, and do not bend the cable along the vertical direction of the screen<br/>
#The screen of e-Paper is relatively fragile, please try to avoid dropping, bumping, and pressing hard.<br/>
#We recommend that customers use the sample program provided by us to test with the corresponding development board after they get the screen.<br/>
<div class="tabbertab" title="Hardware/Software setup">
{{Hardware/Software setting for SPI e-paper}}
<div class="tabbertab" title="Codes description">
{{e-Paper Codes Description}}
=== Display a Frame (DisplayFrame) ===
DisplayFrame is used to send a frame to the module, and the screen will refresh and display it.
|content =  
Process: Send command data start transmission 1 -> Send data of an image to display -> Refresh the screen.
|heading = Introduction
|content = Parameters, principles, and precautions
* About the image data: 4 bits = 1 pixel, doesn’t support Gray scale (can only display black and white). 0000 (binary) stands for a black pixel, 0011 (binary) stands for a white pixel, 0100 (binary) stands for a red pixel.
|img=[[File:Tinker Board 2硬件-test1.png|121px|link=]]
|heading = Starting from the Arduino
|content = Routines developed based on Arduino UNO R3 and their usage instructions
For example:
: 0x00: 2 pixels ■■
: 0x03: 2 pixels ■□
|heading = Start with Raspberry Pi
: 0x30: 2 pixels □■
|content = Using BCM2835, WiringPi, file IO, RPI (Python) library development routines and instructions
: 0x33: 2 pixels □□
: 0x04: 2 pixels ■<font color=red>■</font>
: 0x43: 2 pixels <font color=red>■</font>□
: but 0x66: the state of pixels is uncertain
* This module doesn’t support partial refresh.
* The refresh rate of this module is slow (about 31s), and it will flicker for several times during refreshing. Please be patient.
<div class="tabbertab" title="Resources">
|heading = Start with the Jetson Nano
|content = Use C language, Python developed routines and instructions
|heading = Starting from the STM32
|content = Use STM32CubeMX to develop routines based on STM32F103ZET6 and their usage instructions
{{Commom Instruction of SPI e-paper}}
* [[:File:E-Paper-Driver-HAT-Schematic.pdf|Schematic]]
|heading = Resources
|content = Documentation, procedures and data sheets, etc
==Demo code==
*[ Github]
|heading = FAQ
|content = e-Paper frequently asked questions
* [[:File:7.5inch_e-paper-b-Specification.pdf|Datasheet]]
* [ 7.5inch e-Paper B V2 Specification]
|heading = Support
* [ 7.5inch e-Paper B V3 Specification]
|content = Technical support
==Related Resources==
Notice:<br />
The projects listed are all made and shared by the project owners, Waveshare isn't responsible for project either the update.<br />
*[ Waveshare e-Paper display with SPI]
:This is a post in Arduino Form about our SPI e-Paper thanks to ZinggJM, maybe you want to refer to.
*[ Inkycal Project]
:This is the Inkycal project for reference.
*[ E-Paper Calendar with iCal sync and live weather (shared by user)]
<div class="tabbertab" title="FAQ">
= FAQ =
{{e-paper Hat FAQ}}

Latest revision as of 10:25, 21 July 2022

7.5inch e-Paper HAT (B) Manual



Parameters, principles, and precautions
Tinker Board 2硬件-test1.png

Starting from the Arduino

Routines developed based on Arduino UNO R3 and their usage instructions

Start with Raspberry Pi

Using BCM2835, WiringPi, file IO, RPI (Python) library development routines and instructions

Start with the Jetson Nano

Use C language, Python developed routines and instructions

Starting from the STM32

Use STM32CubeMX to develop routines based on STM32F103ZET6 and their usage instructions


Documentation, procedures and data sheets, etc


e-Paper frequently asked questions


Technical support