Microcontrollers have reduced the development time to integrate a segment LCD display into your electronic product. Many of these microcontrollers also contain an integrated LCD segment driver with additional features.
Advantages of microcontrollers with embedded segment drivers include:
- Reduced cost by eliminating the need for a separate LCD driver chip
- A single chip solution saves PCB real estate
- Assembly cost is reduced due to simplification of the design
- There is more flexibility in segment control than in a dedicated driver chip solution
Single chip LCD driver solutions have proven to be very popular and microcontrollers with integrated LCD segment drivers are available from a Microchip 8-bit PIC series to ARM Cortex 32-bit microcontrollers. A good example of the strong attraction to a single chip solution is the NXPs series; in which Philips® incorporated their popular I2C interface external LCD driver, the PCF8576, along with their ARM Cortex M0 LPC1227 into one single chip solution called the LPC12D27.
Features offered by microcontrollers
Common features offered by microcontroller manufactures:
- Multiplex can drive from about 60 segments up to about 160 segments (4:1x multiplex)
- Dedicated RAM memory (often organized as nibbles [4 bits] with a bit per common) provides faster read and write to the LCD glass
- Low power modes where the microcontrollers draw very little current (sleep mode), but still maintains the LCD
- Unused LCD segment lines can be used as general purpose I/O
Other desirable features not always offered with integrated LCD segment drivers:
- Voltage boost circuitry (charge pump) to enhance contrast at higher multiplex rates
- LCD contrast adjustment directly from microcontrollers, without having to use a separate analog potentiometer.
- Internal temperature measurement that monitors and adjusts contrast values across temperature ranges
- Ability to flash display or particular segments without any intervention by microcontrollers
- Adjustable LCD segment drive frequency
- Helpful to reduce ghosting
Some examples of popular microcontrollers with integrated LCD segment drivers include:
- PIC16F91x : 60 – 96 segment control (4×15 to 4×24)
- PIC18F8XJ90 : 192 segment control (4×48)
- MSP430F4xx family: 56 – 160 segment control ( 4×14 to 4×40)
- MSP430F66xx family: 160 – 320 segment control (4×40 to 8×40 )
- ARM Cortex M3 STM32L15xxx: 160 segment control (4×40 )
- ARM Cortex M0 : LPC12D27: 160 segment control (4×40)
This is a guest Journal from: John Keenan, MicroReady Inc., Electronic Product Design located in Phoenix, AZ. Micro Ready is an electronics product design company based in Arizona and can be contacted at (602) 295-3896.