9.7inch e-Paper HAT
| ||
| ||
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 HAT version.
9.7inch E-Ink display HAT for Raspberry Pi, 1200×825 resolution, 16 gray scale, USB/SPI/I80/I2C interface
More |
Interfaces
5V | 5V |
GND | GND |
MISO | SPI MISO |
MOSI | SPI MOSI |
SCK | SPI SCK |
CS | SPI chip select (Low active) |
RST | External reset pin (Low for reset) |
HRDY | 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 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.
How to use
Working with Raspberry Pi
Installing libraries required
If you want to connect your E-paper screen to Raspberry Pi, you should install some necessary libraries, or else the Demo (click to download) below may work improperly. For more information about how to install the Raspberry Pi libraries, please visit the website: Libraries Installation for RPi.
You can find the detailed presentation about the installations of libraries wiringPi, bcm2835 and python.
Hardware connection
Here is the connection between Raspberry Pi 3B and E-paper.
e-Paper | Raspberry Pi 3B |
---|---|
3.3V | 3.3V |
GND | GND |
DIN | MOSI |
CLK | SCLK |
CS | CE0 |
DC | Pin22/GPIO25 |
RST | Pin11/GPIO17 |
BUSY | Pin18/GPIO24 |
Expected result
1) After the libraries required installed, you can copy the relative programs into your Raspberry Pi, and then enter the corresponding file.
- BCM2835: Execute the command:
make
, to compile the code and generate a fileepd
. Execute the command:sudo ./epd
, the program will run. - WringPi: Execute the command:
make
, to compile the code and generate a fileepd
. Execute the command:sudo ./epd
, the program will run. - Python: Execute the command:
sudo python main.py
2) Image will be displayed on the screen.
- Note:The refresh rate of this module is slow (about 6s), and it will flicker for several times during refreshing. Please be patient.
Working with Arduino
Hardware connection
e-Paper | UNO PLUS (3.3V) |
---|---|
3.3V | 3V3 |
GND | GND |
DIN | D11 |
CLK | D13 |
CS | D10 |
DC | D9 |
RST | D8 |
BUSY | D7 |
Expected result
- Copy the libraries file of Arduino demo code to the libraries folder which is under the installation directory of Arduino IDE, it's path usually is C:\users\username\documents\arduino\libraries. You can also designate the location on Arduino IDE--> File -->Preferences -->Sketchbook location
- Upload the project.
- E-paper will display the image.
Note:
- The refresh rate of this module is slow (about 6s), and it will flicker for several times during refreshing. Please be patient.
Working with the STM32 development board
- Here we use STM32F103ZE development board.
- The demo code is based on HAL, so you can port the demo code to other STM board with STM32CubeMX.
- The demo code can be compiled successfully in Keil v5
Hardware connection
Connecting to the STM32F103ZE:
e-Paper | STM32F103ZE |
---|---|
3.3V | 3V3 |
GND | GND |
DIN | PA7 (MOSI) |
CLK | PA5 (SCK) |
CS | PA4 |
DC | PA2 |
RST | PA1 |
BUSY | PA3 |