5.2 Memory LCD-TFT Display

A 1.28-inch SHARP Memory LCD-TFT has been added to the board to enable interactive applications to be developed. The display has

a high resolution of 128 by 128 pixels, and consumes very little power. It is a reflective monochrome display, so each pixel can only be

light or dark, and no backlight is needed in normal daylight conditions.

The display interface consists of an SPI-compatible serial interface and some extra control signals. Data is sent to the display one line

(128 bits) at a time.

The Memory LCD-TFT display is shared with the kit Board Controller, allowing the Board Controller application to display useful infor-

mation when the user application is not using the display. The user application always controls ownership of the display with

EFM_DISP_SELECT (PA8):

• 0: The Board Controller has control of the display

• 1: The user application (EZR32) has control of the display

EFM_DISP_PWR (PA10) enables power to the display, and must be set high in order to use the display. Data is clocked in on

EFM_DISP_MOSI (PD7) when EFM_DISP_CS (PE11) is high, and the clock is sent on EFM_DISP_SCLK (PC15). The maximum sup-

ported clock speed is 1.1 MHz.

EFM_DISP_COM (PE10) is the "COM Inversion" line. It must be pulsed periodically to prevent static build-up in the display itself.

Please refer to the display application information for details on driving the display:

http://www.sharpmemorylcd.com/1-28-inch-memory-lcd.html

Figure 5.2. 128x128 pixel Memory LCD

5.3 Backup Domain Capacitor

A small super capacitor is provided to evaluate the EZR32 Wonder Gecko MCU's backup power domain. The capacitor has a nominal

value of 33 mF, and is connected with a 100 ohm series resistor to the BU_VIN pin of the EZR32.

Because of the extremely low power consumption of the EZR32 in backup mode (400nA), the capacitor can power a clock application

using the low frequency crystal oscillator (LFXO) for more than 8 hours.

The series resistor allows measuring of the current drawn from the capacitor into the EZR32 device, by simply using a multimeter to

measure the voltage across it. Please refer to the schematic and assembly drawings to locate the series resistor.

EZR32WG 868MHz Wireless Starter Kit

Peripherals

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