71m6534h-igt Maxim Integrated Products, Inc., 71m6534h-igt Datasheet - Page 44

• Manufacturer Part Number: 71m6534h-igt
• Description: Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

71M6533/71M6534 Data Sheet
DIO24 and higher do not have SFR registers for direction control. DIO36 and higher do not have SFR
registers for data access. The direction control of these pins is achieved with the LCD_SEGn[3] registers
and data access is controlled with the LCD_SEGn[0] registers in I/O RAM. DIO56 through DIO58 are ded-
icated DIO pins. They are controlled with DIO_DIR56[7] through DIO_DIR58[7] (direction) and with
DIO_56[4] through DIO_58[4] (data) in I/O RAM.
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, DIO1and DIO2, respectively (see Section
face).
DIO4 and DIO5 can be configured to implement the EEPROM Interface.
Additionally, if DIO6 and DIO7 are configured as DIO and defined as outputs, they can be used as dedicat-
ed pulse outputs (WPULSE = DIO6, VARPULSE = DIO7) using the DIO_PW and DIO_PV registers. In this
case, DIO6 and DIO7 are under CE control. Similarly, DIO8 and DIO9 can be declared pulse outputs
(XPULSE = DIO8, YPULSE = DIO9).
A 3-bit configuration word, I/O RAM register DIO_Rn (0x2009[2:0] through 0x200E[6:4]) can be used for
certain pins (when configured as DIO) to individually assign an internal resource such as an interrupt or a
timer control (DIO_RRX configures the RX pin). This way, DIO pins can be tracked even if they are confi-
gured as outputs. See
sources which can be assigned using DIO_R0 (also called DIO_RPB) through DIO_R7. If more than one
input is connected to the same resource, the resources are combined using a logical OR.
44
Data Register
Configuration (DIO
or LCD segment)
Direction Register
0 = input, 1 = output
71M6533 Pin #
71M6534 Pin #
LCD Segment
See the tables in the I/O RAM Description
DIO43 is controlled by LCD_SEG63[0] which resolves to I/O RAM location 0x2045[4].
Since the control for DIO_24 through DIO_55 is shared with the control for LCD segments, the firmware
must take care not to disturb the DIO pins when accessing the LCD segments and vice versa. Usually,
this requires reading the I/O RAM register, applying a mask and writing back the modified byte.
Tracking DIO pins configured as outputs is useful for pulse counting without external hardware.
Either the interrupts or the counter/timer clocks can be used to count the pulse outputs, or inter-
rupt on the CE’s power failure output.
DIO
Table 39
LCD_BITMAP[71:64] LCD_BITMAP[80:72]
48
68
23
28
4
© 2007-2009 TERIDIAN Semiconductor Corporation
49
69
24
29
5
for DIO pins available for this option.
50
70
25
30
6
51 52* 53* 54* 55* 56
71 72* 73* 74* 75*
50
56
7
57
0*
–
(Section 4.2)
58
1*
–
59
2*
–
60
3*
–
for exact bit locations. For example,
14
19
Always DIO
–
Table 40
57
15
20
–
1.4.6 UART and
58
16
21
–
lists the internal re-
FDS_6533_6534_004
Optical Inter-
v1.1