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EFM32WG Datasheet, PDF (790/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.
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...the world's most energy friendly microcontrollers
It is also possible to connect a dedicated power supply to the LCD module. The LCD external power
supply must be connected to the LCD_BEXT pin and VLCDSEL in LCD_DISPCTRL must be set. In this
mode, the voltage booster should be disabled.
Table 33.7. LCD VLCD
VLCDSEL
0
1
Mode
VDD
VBOOST
VLCD
VDD (same as main external power)
Voltage booster/External VDD
33.3.6 VBOOST Control
The boost voltage is configurable. By programming the VBLEV bits in LCD_DISPCTRL, the boost voltage
level can be adjusted between 3.0V and 3.6V.
The boost circuit will use an update frequency given by the VBFDIV bits in CMU_LCDCTRL, see
Table 33.8 (p. 790) ). It is possible to adjust the frequency to optimize performance for all kinds of LCD
panels (large capacitors may require less frequent updates, while small capacitors may require more
frequent updates). A lower update frequency would in general lead to smaller current consumption.
Table 33.8. LCD VBOOST Frequency
VBFDIV
000
001
010
011
100
101
110
111
VBOOST Update Frequency
LFACLK
LFACLK/2
LFACLK/4
LFACLK/8
LFACLK/16
LFACLK/32
LFACLK/64
LFACLK/128
33.3.7 Frame rate
It is important to choose the correct frame rate for the LCD display. Normally, the frame rate should be
between 30 and 100 Hz. A frame rate below 30 Hz may lead to flickering, while a frame rate above 100
Hz may lead to ghostering and unnecessarily high power consumption.
33.3.7.1 Clock Selection and Prescaler
The LFACLK is prescaled to LFACLKLCDprein the CMU. The available prescaler settings are:
• LFCLK16: LFACLKLCDpre = LFACLK/16
• LFCLK32: LFACLKLCDpre = LFACLK/32
• LFCLK64: LFACLKLCDpre = LFACLK/64
• LFCLK128: LFACLKLCDpre = LFACLK/128
In addition to selecting the correct prescaling, the clock source can be selected in the CMU.
To use this module, the LE interface clock must be enabled in CMU_HFCORECLKEN0, in addition to
the module clock.
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
790
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