There are plenty of small touch screen displays for Raspberry Pi board, including the official 7″ display that connects to the board’s MIPI DSI connector. Some people may prefer getting a small HDMI display however, as it can be used with most devices with an HDMI input port, and the touch screen function may be achieved over USB, I2C or SPI depending on the design.
Elecrow has just launched a new 5″ HDMI display with resistive touch screen designed for the Raspberry Pi boards, and whose main feature is to support backlight control over GPIO 11 in order to lower power consumption according to the announcement tweet from the company.
- Screen – 5″ TFT resistive touch screen display with 800×480 resolution @ 60 Hz;
- LCD Driver IC – Display Future ILI9486L (Likely wrong as this only supports 480×320 resolution)
- Touch controller – XPT2046 4-wire resistive touch controller
- Video Input – HDMI
- Power Supply – 5V/1A via micro USB port or Raspberry Pi header
- Dimensions – 121.11 x 77.93mm
- Weight – 175g
The resistive touch and backlight control functions will only work with a Raspberry Pi model B, 2B, 3B, or 3B+, and potentially Raspberry Pi compatible boards such as Tinker Board or Rock64, but you’d need to carefully check the pins used on the RPI header and potentially modify the software.
Some documentation is available in a wiki. But it’s not very good. It’s unclear how the automatic backlight function works, as in when does the Raspberry Pi decides to turn off the backlight. The Wiki also reads “the backlight can be controlled by a raspberry pi pin, input a high level to pin 11, the backlight will turn on, otherwise, it will be off”,
so it’s unclear where PWM signals can be applied to pin 11 to control the brightness of the backlight [Update: I got an answer on Twitter and the backlight is controlled by a MOSFET to run it on and off only, no brightness control]. The company did not bother providing power consumption numbers either, so we don’t know how much power is safe by turning off the backlight for example.
This 5″ HDMI touch screen display can be purchased directly on Elecrow store for $39.90 plus shipping.