Electronic paper driver related issues:
You only need to design a Boost circuit to provide VGH and other voltages to the e-paper display according to our specifications, and then software design by MCU can light up the e-paper screen.
At present, AIO driver IC products are SPI interface, except for 7.5-inch 8159 driver IC, other sizes 24PIN definition are the same.
In principle, you do not need additional temperature sensor, our screen has internal temperature sensor, error ±2℃, if you want to get more accurate temperature, attaching a temperature sensor is welcomed, we recommend LM75A.
We suggest the two PINS should be connected to GND to avoid external signal interference and abnormal sleep current increase.
According to the description of PIN, VCI VGH VGL VSH VSL VCOM VDD VPP are the power PIN, how much voltage is needed?
You only need to add a VCI input voltage, generally a wide voltage input: 2.4V- 3.6V.
Then according to the reference circuit design of Boost circuit, only the driver IC can produce the corresponding VGH VGL voltage, no additional request.
VDD is the core voltage that drives the IC. It is generated within the IC and does not need to be applied.
VPP is used to burn OTP before our products leave the factory, and customers do not need to add additional.
The maximum SPI speed currently supported by the screen is 20Mhz
The SPI data line of electronic paper is a two-way port, which can be used as output or input. This is often used when reading the IC state or UserID.
BS can be omitted as long as the corresponding SPI mode is selection. BS=1:3 (SCL SDA CS) BS=0:4 (C/D# SCL SDA CS)
BUSY indicates that the IC is BUSY or idle which cannot be omitted. Delay cannot be completely replaced, there are potential risks.
C/D# can be omitted, SPI becomes a 9-bit SPI, and Command&Data selection bits are passed before data transmission. Use with BS.
Because the new generation of driver IC can burn the initialization instruction into OTP, for the client more convenient, we have burned the initialization settings, you only need a few instructions can light up the screen. If you have special Settings, additional instructions can overwrite OTP data.
In order to customers have a better display effect
black and white BN series: 3-4S (above 20℃)
black and white low temperature BS series: 30-50s (-25℃)
black and white red RW series: 18-20s (20-30℃)
black and white yellow YN series: 25 to 30 s (20-30 ℃)
This is the nature of the E-ink displays, through the black and white flickering effect to remove the image and ghost of the previous screen.
Black and white room temperature E-paper and low temperature E-paper can be partial refreshed, brushing time 0.5-1s. Three-color electronic paper cannot.
How is e-paper image data defined?
There are two RAM inside the e-paper driver IC to store black and white pictures and red pictures respectively.
The data format of the current DKE product is as follows:
Black white RAM1 red（yellow）RAM2
black 0 0
white 1 0
red（yellow） X 1
Abnormal BOOST or abnormal SPI communication or IC does not work will all cause BUSY.
Waveform related problems:
What is the driving waveform?
The display of electrophoretic electronic paper is determined by the space position of particles in microcapsules or microcups. The electrophoretic phenomenon of particles occurs under the action of voltage. The voltage time series that causes particles to electrophoretic movement is the driving waveform of electronic paper. The driving waveform is the core part of the electronic paper display. By adjusting the waveform, the electronic paper products have a better display effect. The screen refresh time is mainly determined by the waveform. Each batch of newly produced electronic paper modules will have different effects, the WF of the same group may not be able to cover, so we need to adjust the waveform to eliminate the difference and ensure the consistency of products.
OTP is a function provided by driver IC to store LUTS. Since electronic paper is easily affected by temperature, we will divide it into multiple temperature ranges and adjust a set of waveforms for each temperature range. We can use OTP to store waveforms at different temperatures, so that EPD can present the best status within its operating temperature range.
Solomon IC can be burned multiple times, FITI and UC can be burned twice. (7.5 low DPI Flash can be burned multiple times).
It can be optimized, but not exactly the same as the original state due to aging and other issues.
Normally, we try to ensure the single pixel is full at 35-40℃ during debugging. However, due to the inconsistency of the original materials of electronic paper, it is normal that one or two states of individual batches are not displayed well. We guarantee that the bar code of black and red characters on white background must be readable at 35-40℃.
DKE conventional temperature parts are divided as follows (℃):
Black and white normal temperature BN series: 0-5 5-10 10-15 15-20 20-30 30-40 40-50
Black and white low temperature BS series: -25-- 20-20 -- 15-15 -- 10-10 --0 --10 10-20 20-30
Black and white red RW series: 0-3 3-6 6-10 10-15 15-20 20-30 30-35 35-40 Black and white yellow YN series: 0-3 3-6 6-10 10-15 15-20 20-30 30-40
Can it be refreshed beyond the upper and lower limits of the temperature range?
We have driving waveform in the upper/lower limit of the temperature range, although the display effect is not guaranteed, but can be refreshed.
The driving waveform directly affects the power consumption, it determines the refresh time. The refreshing frequency and driving mode of the waveform affect the average current and pulse current.
This is not possible, because there is a big difference between the display principle of electronic paper and liquid crystal, the length of the driving waveform directly affects the display effect and residual shadow effect, so it cannot be shortened.
L A B ΔE what do these values represent?
At present, the main measurement standard for EPD display performance is L* A * B * value,
L* stands for brightness; A * indicates red and green, and the greater the a value, the fuller the red; B star is yellow and blue. The bigger the b, the fuller the yellow.
Black and white screen only focus on L* value
black and white red screen focus on L* and A *
black and white yellow screen focus on L* and B *
ΔE represents color difference, can also represent residual shadow, ΔE the greater the color difference, the more serious residual shadow.
Demo kit question:
Our Demo board is just for customers to evaluate the e-paper display screen.
It divided into motherboard and BOOST driver board; USB powered. The customer can upload the picture through the upper computer, there are four buttons can display three pictures and a whole white pic.
If all Leds are on, the mainboard does not match the Firmware, means you need to replace the board or Firmware.
The screen is a three-color screen, and the firmware is a black-and-white screen, so the display is abnormal.
By default, 0-16 is black, 240-255 is white, and other RGB values will be displayed in red. Therefore, it is recommended that customers use BMP format pictures when making pictures, and there is no gray scale, only black, white and red colors.
Our DEMO can use black, white and red firmware and images for black, white and yellow screens, which are compatible.
For small-size products, such as 2.9-inch 128*296, 128 is source and 296 is gate, while for large-size products, 4.2-inch products, source is 400 and gate is 300.
Our upper computer needs the picture to be Gate in the horizontal direction and Source in the vertical direction, so the picture can be displayed correctly only when it is in the right direction.
Please place firmware in the directory with non-Chinese characters.