Displays can be used to communicate with a user/operator. They work much similar to a computer screen but typically are much smaller. Displays can be as simple as a matrix-style LCD monochrome text display and go all the way up to sophisticated true color graphics screens, some providing touch input support.
Technologies
Most DIY displays use one of these technologies:
- Simple LCD: Simple liquid crystal displays can display monochrome text similar to LED matrix displays
- TFT LCD: thin-film-transistors enhance addressability and contrast and can display any graphical content in many thousand colors. In this section I am reviewing the Human Interface components I like and use in my projects
- OLED: organic light emitting diodes provide the best display quality and contrast: no backlighting is required since each pixel is an individual light source. Production is still expensive which is why OLED displays are either small or very expensive. Most OLED displays used for DIY are single-color although affordable full color displays are emerging.
Interfaces
To connect displays to microcontrollers, these two interfaces are commonly used:
- I2C: This simple two-wire protocol is used for small monochrome displays with limited data transfer rates
- SPI: The clock-based four-wire-protocol is typically found in larger and colored displays where much larger amounts of data need to be transferred
Simple matrix-style LCD text displays typically use specific driver boards which in turn can be addressed using I2C.
Operating Voltages
The underlying technology used by all of these displays does not require high voltages and is typically operated with 3.3V. Some come with built-in voltage regulators and accept a wide range of input voltage. Make sure you always check the display datasheet to not exceed the operating voltage.
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(content created May 05, 2024)