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2014-07-02 - Tiny Gecko Family - d0034_Rev1.20
510
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Table 29.12. FCPRESC
FCPRESC
Mode
Description
General equation
00
Div1
CLK
FRAME
/1
01
Div2
CLK
FRAME
/2
10
Div4
CLK
FRAME
/4
11
Div8
CLK
FRAME
/8
CLK
FC
= CLK
FRAME
/2
FCPRESC
The top value for the Frame Counter is set by FCTOP in LCD_BACTRL. Every time the frame counter
reaches zero, it is reloaded with the top value, and at the same time an event, which can cause an
interrupt, data update, blink, or an animation state transition is triggered.
LCD Event Frequency Equation
CLK
EVENT
= CLK
FC
/(1 + FCTOP[5:0]) Hz
(29.2)
The above equation shows how to set-up the LCD event frequency. In this example, the frame rate is
64Hz, and the LCD event frequency should be set-up to 2 seconds.
Example 29.1. LCD Event Frequency Example
• Write FCPRESC to 3 => CLK
FC
= 8Hz (0.125 seconds)
• Write FCTOP to 15 => CLK
EVENT
= 0.5Hz (2 seconds)
If higher resolution is required, configure a lower prescaler value and increase the FCPRESC in
LCD_BACTRL accordingly (e.g. FCPRESC = 2, FCTOP = 31).
Figure 29.43. LCD Clock System in LCD Driver
LFXO
LFRCO
Count er
FDIV[2:0]
LCD Fram e
Count er
FCTOP[5:0]
LFACLK
LCDpre
CLK
FC
CLK
EVENT
div2
CLK
FRAME
MUX in
LCD_DISPCTRL
LFACLK
LCD
LCD in
CMU_LFAPRESC0
CMU
div16
div32
div64
div128
div1
div2
div4
div8
FCPRESC in
LCD_BACTRL
LFACLK
div4
div6
div8
div12
div16
st at ic
duplex
t riplex
quadruplex
sex t aplex
oct aplex
29.3.11 LCD Interrupt
The LCD interrupt can be used to synchronize data update. The FC interrupt flag is set at every LCD
Frame Counter Event, which must be set-up separately. The interrupt is enabled by setting FC bit in
LCD_IEN.
Summary of Contents for EFM32TG
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