xe8802 Semtech Corporation, xe8802 Datasheet - Page 156

• Manufacturer Part Number: xe8802
• Description: Data Acquisition Soc With 16+10 Bit Zoomingadc? Embedded Risc Controller And Lcd Driver
• Manufacturer: Semtech Corporation

The voltage generator has to be configured for the use of the internal reference (VgenRefEn=1 in RegVgenCfg0).
The generator has to run (VgenOff=0 and VgenStdb=0 in RegVgenCfg0). It has to generate 1/3 bias
(VgenMode=0 in RegVgenCfg0) and the generator output impedance is set to minimum (VgenClkSel=11 in
RegVgenCfg0).
The LCD driver is set to 1:3 multiplexing (LcdMux=10 in RegLcdOn) and the waveform generator is enabled
(LcdSleep=0 in RegLcdOn). All pads are set into the LCD driver mode by setting all bits of register RegLcdSe to
1. To select a frame rate of about 50Hz, set the bits LcdFreq=10 and LcdDivFreq=110 in RegLcdClkFrame. Note
that the precision of the frame frequency depends on the selected clock source (see clock block documentation).
The 93 segments are on or off depending on the bits set in the registers RegLcdDataN. Only the bits 0,1,2 and
4,5,6 of these registers are used in 1:3 multiplexing. The bits 3 and 7 are not important. Figure 19-7 shows the
generated waveforms for nine segments. The segments connected to pad_lcd_io[0] are all on (LcdData0[2:0]=111
in RegLcdData0), the segments connected to pad_lcd_io[1] are all off (LcdData0[6:4]=000 in RegLcdData0) and
the segments connected to pad_lcd_io[2] are partially on, partially off (LcdData1[2:0]=101 in RegLcdData1). The
© Semtech 2006
pad_lcd_com0
pad_lcd_com1
pad_lcd_io[31]
pad_lcd_io[0]
pad_lcd_io[1]
pad_lcd_io[2]
V3
V2
V1
V0
V3
V2
V1
V0
V3
V2
V1
V0
V3
V2
V1
V0
V3
V2
V1
V0
V3
V2
V1
V0
Figure 19-7. 1:3 MUX mode waveforms
XE8802 Sensing Machine Data Acquisition MCU
19-12
with ZoomingADC™ and LCD driver
-V1
-V2
-V3
-V1
-V2
-V3
-V1
-V2
-V3
V3
V2
V1
V0
V3
V2
V1
V0
V3
V2
V1
V0
pad_lcd_com0 - pad_lcd_io[0] (on)
pad_lcd_io[31] - pad_lcd_io[2] (on)
pad_lcd_com1 - pad_lcd_io[1] (off)
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