71M6521BE
Energy Meter IC
DATA SHEET
JANUARY 2008
Connecting LCDs
The 71M6521BE has a LCD controller on-chip capable of controlling static or multiplexed LCDs. Figure 30 shows the basic
connection for a LCD.
6521
LCD
segments
commons
Figure 30: Connecting LCDs
Nineteen pins are dedicated LCD segment pins (SEG0 to SEG18). If more pins are needed to drive segments, the dual-
function pins CKTEST/SEG19, E_RXTX/SEG38, E_TCLK/SEG33, and E_RST/SEG32 can be used.
Even more segment pins are available in the form of combined DIO and segment pins (SEG24/DIO4 to SEG31/DIO11,
SEG34/DIO14 to SEG37/DIO17).
The split between DIO and LCD use of the combined pins is controlled with the DIO register LCD_NUM. LCD_NUM can be
assigned any number between 0 and 18. The first dual-purpose pin to be allocated as LCD is SEG37/DIO17. Thus if
LCD_NUM=5, SEG37 will be configured as LCD. The remaining SEG36 to SEG24 will be configured as DIO16 to DIO4. DIO1
and DIO2 are always available, if not used for the optical port.
Pins CKTEST/SEG19, E_RXTX/SEG38, E_TCLK/SEG33, and E_RST/SEG32 are not affected by LCD_NUM.
V1.0
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