US$1.79 ~ 2.29
EDS812 5V 3 Bit 8 Characters LCD Display Module Digit Clock LCD Screen No Backlight/White/Yellow-green
2.Appearance Size: 30.7×16.2×2.8mm
3.Visual Area Size: 27.9×10.0mm
4.Display Mode: HTN, positive display
5.Polaroid Type: Semi-transparent
6.Visual Angle: 6 O'CLOCK
7.Connection Type:metal pi
8.Driving Way: static
9. Driving Voltage: 5.0V
10.Operation Temperature: -30 ° C ~ 80 ° C
11.Storage Temperature: -40 ° C ~ 90 ° C
1. The LCD screen has a reflective mode, a semi-transparent mode, and a full transparent mode, do not know what is the difference, how to choose?
– Reflection mode: The lower polarizer is opaque, so it cannot be used in backlight. It is suitable for occasions with daytime or external light source. The advantage is that the contrast is higher;
– Full transmission mode: the transmission rate is about 40%, it must be used with the backlight (otherwise, the component or PCB under the screen will be seen), the advantage is that the backlight brightness is high;
– Semi-transparent mode: Between reflection and full-transmission mode, the transmission rate is about 30%. It can be used if it is connected to the backlight. It is more flexible.
2. LCD segment code screen has static drive and dynamic drive, how to distinguish?
– Static drive: There is only one common COM, and each pixel is a separate electrode. The advantage is that the display effect is better than that of the dynamic drive, and the disadvantage is that there are many pins;
– Dynamic drive: More than 2 common COMs, each electrode controls at least 2 or more pixels, and requires time division scan mode drive.
3. Can the LCD segment code screen be DC driven? What is the difference between driving with LED digital tube?
– LED digital tube: DC drive, connected by a common terminal at the anode or cathode, with the difference of common or common;
– LCD screen: AC drive, common side and driver side need to add AC square wave signal, relying on changing the phase of the two to control whether the corresponding pixel is displayed, this is the difference between the essence of LED digital tube, so there is no common yin or The saying of Gongyang. Never connect the common terminal COM directly to the ground, and display it by controlling the drive terminal to a high level. This will damage the LCD screen for a long time.
4. LCD segment code screen can be used without driver chip, direct MCU driver?
– Statically driven segment code screen, if the number of IO ports of the microcontroller is enough, it can be directly driven;
– The dynamically driven screen is driven by a time-division scan mode, and the bias waveform is not well simulated, so theoretically it cannot be directly driven by the microcontroller. Some analog voltage dividers can be used to generate analog bias voltages. They can also be directly driven by a single-chip microcomputer. However, the programming is too complicated and the display effect is not ideal. It is best to use a dedicated segment code LCD driver chip. The most commonly used is the HT1621, which is low in price. 3-wire SPI serial port driver, programming is also simple.
EDS139 product sample download:
EDS139 backlight drawing download:
LCD application technology:
How the LCD display works:
Static LCD display drive mode:
1 x No/White/Yellow-green EDS139 LCD Display Screen