Connecting an LCD to computer modules such as BeagleBone and Raspberry Pi, has always involved a degree of compromise.
4D Systems believes it is practical to use the I²C interface rather than traditional LCD capes which utilise the analogue inputs that are rather susceptible to external EMI.
The resistive touch function uses an on-board Microchip AR1021 resistive touch controller that communicates directly with the BeagleBone Black over I²C.
The capacitive touch models incorporate a cover lens bezel that enables the construction of a robust yet slim design with ease, utilizing Focaltec CTP controller that communicates over I²C.
The firm’s BeagleBone Black LCD add-ons comprises 4.3-, 5.0- and 7.0- inch models, each equipped with a 30-pin FPC cable that plugs into the supplied gen4 cape adapter board. No additional connectors are required to operate the display since all power, control and data signals come through the FPC.
Use of an adapter board, the cape that plugs directly into the BeagleBone Black, permits ease of using different display sizes to suit the application. In addition, each cape has the choice of either resistive or capacitive touch options.
Changing the display backlight brightness is facilitated through the use of a TI TPS61165 backlight driver IC for which a Linux driver is also provided. This method of varying the brightness is more stable and less noisy than using PWM signals.
The BeagleBone Black Wireless and BeagleBone Green boards are also supported.