71M6521DE/71M6521FE
Energy Meter IC
DATASHEET
JANUARY 2008
The PB pin is a dedicated digital input. In addition, if the optical UART is not used, OPT_TX and OPT_RX can be configured
as dedicated DIO pins. Thus, in addition to the 16 general-purpose DIO pins (DIO4…DIO11, DIO14…DIO21), there are three
additional pins that can be used for digital input and output.
71M6521
71M6521
V3P3SYS
V3P3SYS
VBAT
3.3V
3.3V
VBAT
LED
V3P3D
V3P3D
DIO1
DIO1
R
LED
R
DGND
DGND
Not recommended
Recommended
Figure 8: Connecting an External Load to DIO Pins
DIO_R Value
Resource Selected for DIO Pin
NONE
0
1
2
3
4
5
6
7
Reserved
T0 (counter0 clock)
T1 (counter1 clock)
High priority I/O interrupt (INT0 rising)
Low priority I/O interrupt (INT1 rising)
High priority I/O interrupt (INT0 falling)
Low priority I/O interrupt (INT1 falling)
Table 56: Selectable Controls using the DIO_DIR Bits
LCD Drivers
The device in the 68-pin QFN package contains 20 dedicated LCD segment drivers in addition to the 18 multi-use pins
described above. Thus, the device is capable of driving between 80 to 152 pixels of LCD display with 25% duty cycle (or 60 to
114 pixels with 33% duty cycle). At eight pixels per digit, this corresponds to 10 to 19 digits.
The device in the 64-pin LQFP package contains 20 dedicated LCD segment drivers in addition to the 15 multi-use pins
described above. Thus, the device is capable of driving between 80 to 140 pixels of LCD display with 25% duty cycle (or 60 to
105 pixels with 33% duty cycle). At eight pixels per digit, this corresponds to 10 to 17 digits.
The LCD drivers are grouped into four commons and up to 38 segment drivers (68-pin package), or 4 commons and 35
segment drivers (64-pin package). The LCD interface is flexible and can drive either digit segments or enunciator symbols.
Segment drivers SEG18 and SEG19 can be configured to blink at either 0.5Hz or 1Hz. The blink rate is controlled by LCD_Y.
There can be up to four pixels/segments connected to each of these drivers. LCD_BLKMAP18[3:0] and LCD_BLKMAP19[3:0]
identify which pixels, if any, are to blink.
v1.0
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