4.2inch e-Paper

Introduction

Note: The raw panel require a driver board, If you are the first time use this e-Paper, we recommend you to buy the HAT version or buy more one driver hat for easy use, otherwise you need to make the driver board yourself. And this instruction is based on the version with PCB or driver board.

400x300, 4.2inch E-Ink display module, SPI interface

Interfaces

VCC	3.3V
GND	GND
DIN	SPI MOSI
CLK	SPI SCK
CS	SPI chip select (Low active)
DC	Data/Command control pin (High for data, and low for command)
RST	External reset pin (Low for reset)
BUSY	Busy state output pin (Low for busy)

Working principle

Introduction

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 suspending 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 sunshine, the E-paper screen still has high visibility with a wide viewing angle of 180 degree. It is the ideal choice for E-reading.

Communication protocol

Note: Different from the traditional SPI protocol, the data line from the slave to the master is hidden since the device only has display requirement.

CS is slave chip select, when CS is low, the chip is enabled.
DC is data/command control pin, when DC = 0, write command, when DC = 1, write data.
SCLK is the SPI communication clock.
SDIN is the data line from the master to the slave in SPI communication.

SPI communication has data transfer timing, which is combined by CPHA and CPOL.

CPOL determines the level of the serial synchronous clock at idle state. When CPOL = 0, the level is Low. However, CPOL has little effect to the transmission.
CPHA determines whether data is collected at the first clock edge or at the second clock edge of serial synchronous clock; when CPHL = 0, data is collected at the first clock edge.

There are 4 SPI communication modes. SPI0 is commonly used, in which CPHL = 0, CPOL = 0.

As you can see from the figure above, data transmission starts at the first falling edge of SCLK, and 8 bits of data are transferred in one clock cycle. In here, SPI0 is in used, and data is transferred by bits, MSB first.

Documentation

Demo code

Github

Datasheets

Datasheets

Related Resources

This is a post in Arduino Form about our SPI e-Paper thanks to ZinggJM, maybe you want to refer to.

Waveshare e-Paper display with SPI

Question:

Working requirements of e-Paper?

Answer:

Two-color B/W e-paper
- 【Working】Temperature: 0~50°C; Humidity: 35%~65%RH
- 【Storage】Temperature: ≤30°C; Humidity: ≤55%RH; Max storage time: 6 months
- 【Transport】Temperature: -25~70°C; Max transport time: 10 days
- 【Unpack】Temperature: 20°C±5°C; Humidity: 50%RH±5%RH; Max storage time: Should be assembled in 72h
Three-Color e-Paper
- 【Working】Temperature: 0~40°C; Humidity: 35%~65%RH
- 【Storage】Temperature: ≤30°C; Humidity: ≤55%RH; Max storage time: 3 months
- 【Transport】Temperature: -25~60°C; Max transport time: 10 days
- 【Unpack】Temperature: 20°C±5°C; Humidity: 50%RH±5%RH; Max storage time: Should be assembled in 72h

When store three-color e-Paper, please refresh it to white, and keep the screen upward. Note that you need to update it at least every three months.

Question:

What do you need to note about e-Paper refreshing?

Answer:

Refresh mode
- Full refresh: e-Paper flicker when full refreshing to remove ghost image for best display.
- Partial refresh: It don't flicker if you use partial refresh (only some of the two-color e-paper support partial refresh). Note that you cannot use Partial refresh all the time, you should full refresh e-paper regularly, otherwise, ghost problem will get worse even damage.
Refresh rate
- When using, you should set the update interval at least 180s.(except Partial supportable types)
- Please set the e-Paper to sleep mode or power off it directly, otherwise, the e-Paper is damaged because of working in high voltage for long time.
- You need to update the content of three-color e-Paper at least one time every 24h to avoid from burn-in problem.
Working place
We recommend you to use the e-Paper indoor. If you need to set the e-paper outdoor, Please place the e-paper in shadow and protect it from UV. When you designed you e-paper product, you should take care about the working situation like temperature, humidity, etc.

Question:

How much could the flexible e-paper be bended

Answer:

The IC part of e-Paper cannot be bended, you can bend the display area in degree larger than 60°C

Question:

Why the e-Paper cant work with Arduino?

Answer:

The I/O level of Arduino is 5V, and the e-Paper should be driven with 3V3. If your Arduino cant drive the e-Paper successfully, please try to convert the level to 3.3V

You can also try to connect the Vcc pin to the 5V of Arduino to see whether the e-Paper works, but we recommend you not to use 5V for a long time.

Question:

Why does the color of e-Paper look a little black or grey?

Answer:

You can try to change the value of Vcom on demo codes.

Question:

Three-color e-paper looks more red/yellow than the picture on website?

Answer:

Because of different batch, some of them have aberration. Store the e-Paper right side up will reduce it. And if the e-Paper didn't be refreshed for long time, it will become more and more red/yellow. Please use the demo code to refresh the e-paper for several times in this case.

Question:

Why my e-paper has ghosting problem after working for some days

Answer:

Please set the e-paper to sleep mode or disconnect it if you needn't refresh the e-paper but need to power on your development board or Raspberry Pi for long time.Otherwise, the voltage of panel keeps high and it will damage the panel

Question:

Why the FPC of the e-Paper is broken after using for some times?

Answer:

Please make sure you have used it in correct way.

To：

Dear Customers, There may be a lag of several hours before we could process your order, depending on the time difference between your location and ours. Sincerely hoping your understanding!

Email(support)

services01@spotpear.com

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4.2inch E Ink raw display, black, white, 400x300

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