E-paper display's different update mode

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Time of issue:2021-07-08 10:08
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(Summary description)

E-paper display's different update mode

(Summary description)

Categories:Blog
Author:
Origin:
Time of issue:2021-07-08 10:08
Views:

Information

There are usually three kinds of update mode of E-paper display:

Update Mode	Full Update	Patial Update	Fast Update
Supported colors	Three-colors (BWR) and monochrome (BW)	Monochrome (BW)	Monochrome (BW)
Image data upload	Full screen image New image buffer with all 0x00 buffer	Partial window image Previous image buffer and new image buffer	Full screen image Previous image buffer and new image buffer
Panel update	Whole screen Flashing effect	Partial window Fast mode	Whole screen Fast mode
Image quality	Optimal quality	Possible ghosting	Possible ghosting
Upload image speed	Slow	Fast	Slow
Update image speed	Slow	Fast	Fast
Overall speed	Slow	Fastest	Faster

Tip: So why don't we use partial or fast updates all the time? Why bother with all the flickering? The optical performance of a full update is way better. You get better contrast and a well defined image. If you use partial or fast updates too often, you'll get the so called "ghosting" effect. Ghosting looks like old display content is burned in and shows through in the new image. You can get rid of ghosting by doing another full update, therefore, our recommendation is to do one full update after five or six partial or fast updates.

Test Object: 2.9inch E-Paper Display
Note: We provide the results and parameters as reference for you and please contact us if you want to learn more.

①	②	③	④	⑤
Platforms	Hardware Connection and IO Settings	Demonstration of Updates	Refresh Time and Current	Comparison Among Codes

PLATFORMS

Goodisplay has multiple development plans for driving EPDs. Here we mainly introduce STM32, EPS32 and ESP8266 to you. Users can also drive EPDs via Raspberry Pi/ Raspberry Pi Pico, which you can learn more on our WEBSITE.

STM32

STM32 based on Cortx-M, has 32-bit microcontroller, supports broad 32-bit applications including high performance, real time, processing digital signal and low-power, low-voltage operation and is a perfectly integrated and easy development kit. There is a broad product line based on STM32 for its industial-standardized core, plenty of tools and softwares to support it. It is an ideal choice for many products. Its MCU, STM32F103VET6 and has related drivers that can be transplanted onto users' development plan to drive EPDs.

ESP8266

For easy understanding, we may apprehend the ESP8266 as a MCU with WiFi function, which we can use another MCU to communicate following the same instruction to implement operations. ESP8266 is a serial port WiFi module, with an integrated MCU to realize serial communication. It is easy to learn and small enough for embedded development. It designed for mobile deveces, smart wearables and IoT products. Relyed on multiple patents, it has realized ultra-low power consumption and has power-saving mode for all kinds of related scenarios.

ESP32

Likewise,we may also apprehend the ESP32 as a MCU with WiFi+BT function, which we can use another MCU to communicate following the same instruction to implement operations. Compared with ESP8266, it has BT function and a faster and lower-power CPU.It is easy to learn and small enough for embedded development. It designed for mobile deveces, smart wearables and IoT products. Relyed on multiple patents, it has realized ultra-low power consumption and has power-saving mode for all kinds of related scenarios.

DEMONSTRATION OF UPDATES

IO settings have already been done previously so that users only need to connect the adaptor board to the main board.
In order to realize different updates users only need to revise the software.
The following section will detail the IO settings:

CONNECTION

IO SETTINGS

Connecting STM32F103VET6
EPD	STM32
VCC	3.3V
GND	GND
BUSY	PE13
RES	PE14
D/C	PE15
CS	PD8
SCK	PD9
SDI	PD10

//CS-->PD8 SCK-->PD9 SDO--->PD10
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8|GPIO_Pin_9|GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_Init(GPIOD, &GPIO_InitStructure);

// D/C--->PE15 RES-->PE14
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14|GPIO_Pin_15;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_Init(GPIOE, &GPIO_InitStructure);

// BUSY--->PE13
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_Init(GPIOE, &GPIO_InitStructure);

Connecting ESP8266
EPD	STM32
VCC	3.3V
GND	GND
BUSY	D0
RES	D1
D/C	D2
CS	D5
SCK	D6
SDI	D7

//IO settings
int BUSY_Pin = D0;
int RES_Pin = D1;
int DC_Pin = D2;
int CS_Pin = D5;
int SCK_Pin = D6;
int SDI_Pin = D7;

Connecting ESP32
EPD	STM32
VCC	3.3V
GND	GND
BUSY	A14
RES	A15
D/C	A16
CS	A17
SCK	A18
SDI	A19

//IO settings
int BUSY_Pin = A14;
int RES_Pin = A15;
int DC_Pin = A16;
int CS_Pin = A17;
int SCK_Pin = A18;
int SDI_Pin = A19;

REFRESH TIME AND CURRENT

Take GDEW029T5D as an example，we can use the methods below to change the price.


	gImage_1		gImage_2		gImage_3

Monochrome E-paper Display（GDEW029T5D)
1. Full Update Mode
2. Partial Update Mode
3. Fast Update Mode

Tri-color E-paper Display（GDEH029Z13)
1. Full Update Mode
2. Partial Update Mode Note: The partial update here is only when black and white are displayed, not real partial update.

REFRESH TIME AND CURRENT

The following results are the representative values of the same EPD(GDEW029T5D) under the same conditions.

Type	Mode	Time(s)	Current(mA)
GDEW029T5D (B/W)	Full update	3s	2.6mA
	Partial update	0.3s	2.5mA
	Fast update	0.8s	2.1mA
GDEH029Z13(B/W/R)	Full update	13s	4mA
GDEH029Z13(B/W/R)	Partial update	0.3s	2.8mA

COMPARISON AMONG CODES

GDEW029T5D(B/W)
Main Function	Full update	Partial update	Fast update
	EPD_init(); PIC_display(gImage_1); EPD_sleep(); EPD_init(); PIC_display(gImage_2); EPD_sleep(); EPD_init(); PIC_display(gImage_3); EPD_sleep();	EPD_init(); EPD_partial_display(0,0,gImage_1,gImage_1,296,128,0); EPD_partial_display(0,0,gImage_1,gImage_2,296,128,1); EPD_partial_display(0,0,gImage_2,gImage_3,296,128,1); EPD_sleep();	EPD_init(); EPD_full_display(gImage_1,gImage_1,0); EPD_sleep(); EPD_init(); EPD_full_display(gImage_1,gImage_2,1); EPD_deep_sleep(); EPD_init(); EPD_full_display(gImage_2,gImage_3,1); EPD_sleep();
Note: gImage_1,gImage_2,gImage_3 are 296128, gImage_22g and Image_33 are 152128.
Initialization	Full mode	Partial mode	Fast mode
	EPD_W21_Init(); EPD_W21_WriteCMD(0x04); lcd_chkstatus(); EPD_W21_WriteCMD(0x00); EPD_W21_WriteDATA(0x1f); EPD_W21_WriteCMD(0x61); EPD_W21_WriteDATA (0x80); EPD_W21_WriteDATA (0x01); EPD_W21_WriteDATA (0x28); EPD_W21_WriteCMD(0X50); EPD_W21_WriteDATA(0x97);	EPD_W21_Init(); EPD_W21_WriteCMD(0x01); EPD_W21_WriteDATA (0x03); EPD_W21_WriteDATA (0x00); EPD_W21_WriteDATA (0x2b); EPD_W21_WriteDATA (0x2b); EPD_W21_WriteDATA (0x13); EPD_W21_WriteCMD(0x06); EPD_W21_WriteDATA (0x17); EPD_W21_WriteDATA (0x17); EPD_W21_WriteDATA (0x17); EPD_W21_WriteCMD(0x04); lcd_chkstatus(); EPD_W21_WriteCMD(0x00); EPD_W21_WriteDATA(0xbf); EPD_W21_WriteCMD(0x30); EPD_W21_WriteDATA (0x3c); EPD_W21_WriteCMD(0x61); EPD_W21_WriteDATA(0x80); EPD_W21_WriteDATA(0x01); EPD_W21_WriteDATA(0x28); EPD_W21_WriteCMD(0x82); EPD_W21_WriteDATA (0x10); EPD_W21_WriteCMD(0X50); EPD_W21_WriteDATA(0x97);	EPD_W21_Init(); EPD_W21_WriteCMD(0x01); EPD_W21_WriteDATA (0x03); EPD_W21_WriteDATA (0x00); EPD_W21_WriteDATA (0x2b); EPD_W21_WriteDATA (0x2b); EPD_W21_WriteDATA (0x03); EPD_W21_WriteCMD(0x06); EPD_W21_WriteDATA (0x17); EPD_W21_WriteDATA (0x17); EPD_W21_WriteDATA (0x17); EPD_W21_WriteCMD(0x04); lcd_chkstatus(); EPD_W21_WriteCMD(0x00); EPD_W21_WriteDATA(0xbf); EPD_W21_WriteCMD(0x30); EPD_W21_WriteDATA (0x3c); EPD_W21_WriteCMD(0x61); EPD_W21_WriteDATA(0x80); EPD_W21_WriteDATA(0x01); EPD_W21_WriteDATA(0x28); EPD_W21_WriteCMD(0x82); EPD_W21_WriteDATA (0x12); EPD_W21_WriteCMD(0X50); EPD_W21_WriteDATA(0x97);
Note: In different methods of EPD update, Function EPD_W21_Init（）is the same as Function lcd_chkstatus()
Note: In different methods of EPD update, display functions are different and please refer to the detailed code in the program while the sleep function is the same.

GDHW029Z13(B/W/R)
Main Function	Full update	Partial update
	EPD_init(); PIC_display(gImage_BW1, gImage_R1); EPD_sleep();	EPD_init_LUT(); EPD_partial_display_Color(8,16,gImage_1,gImage_1,200,24,0); EPD_partial_display_Color(8,16,gImage_2,gImage_2,200,24,0); EPD_sleep();
Initialization	EPD_W21_Init(); EPD_W21_WriteCMD(0x04); lcd_chkstatus(); EPD_W21_WriteCMD(0x00); EPD_W21_WriteDATA(0x0f); EPD_W21_WriteCMD(0x61); EPD_W21_WriteDATA (0x80); EPD_W21_WriteDATA (0x01); EPD_W21_WriteDATA (0x28); EPD_W21_WriteCMD(0X50); EPD_W21_WriteDATA(0x77);	EPD_W21_Init(); EPD_W21_WriteCMD(0x01); EPD_W21_WriteDATA(0x03); EPD_W21_WriteDATA(0x00); EPD_W21_WriteDATA(0x2b); EPD_W21_WriteDATA(0x2b); EPD_W21_WriteDATA(0x13); EPD_W21_WriteCMD(0x06); EPD_W21_WriteDATA(0x17); EPD_W21_WriteDATA(0x17); EPD_W21_WriteDATA(0x17); EPD_W21_WriteCMD(0x04); lcd_chkstatus(); EPD_W21_WriteCMD(0x00); EPD_W21_WriteDATA(0xbf); EPD_W21_WriteCMD(0x30); EPD_W21_WriteDATA(0x3c); EPD_W21_WriteCMD(0x61); EPD_W21_WriteDATA(0x68); EPD_W21_WriteDATA(0x00); EPD_W21_WriteDATA(0xd4); EPD_W21_WriteCMD(0x82); EPD_W21_WriteDATA(0x12); EPD_W21_WriteCMD(0X50); EPD_W21_WriteDATA(0x97); lut1();
Note: In different methods of EPD update, Function EPD_W21_Init（）is the same as Function lcd_chkstatus()
Note: In different methods of EPD update, display functions are different and please refer to the detailed code in the program while the sleep function is the same