71M6403
Electronic Trip Unit
SEPTEMBER 2006
On-Chip Resources
DIO Ports
The 71M6402 includes up to 22 pins of general purpose digital I/O. 18 of these pins are dual function and can alternatively be
used as LCD drivers. Figure 6 shows a block diagram of the DIO section.
On reset or power-up, all DIO pins are inputs until they are configured for the desired direction. The pins are configured and con-
trolled by the DIO and DIO_DIR registers (SFRs) and by the five bits of the I/O register LCD_NUM (0x2020[4:0]). See the
description for LCD_NUM in the I/O RAM Section for a table listing the available segment pins versus DIO pins, depending on
the selection for LCD_NUM. Generally, increasing the value for LCD_NUM will configure an increasing number of general
purpose pins to be LCD segment pins, starting at the higher pin numbers.
COM0..3
LCD DISPLAY
DRIVER
SEG6/SRDY
LCD_EN
SEG0..2, SEG3/SCLK,
LCD_FS
LCD_MODE
LCD_NUM
LCD_MODE
SEG4/SSDATA,
SEG5/SFR, SEG7..19
LCD_CLK
SEG20..23
SEG24/DIO4 ..
SEG27/DIO7
SEG28/DIO8 ..
DIGITAL I/O
DIO_EEX
FAULT_PULSE
STROBE
DIO_IN
SEG31/DIO11
SEG32/DIO12 ..
SEG41/DIO21
DIO_0..3
DIO_OUT
LCD_NUM
DIO_GP
Figure 6: DIO Ports Block Diagram
Each pin declared as DIO can be configured independently as an input or output with the bits of the DIO_DIRn registers. Table
51 lists the direction registers and configurability associated with each group of DIO pins. Table 52 shows the configuration for a
DIO pin through its associated bit in its DIO_DIR register.
Direction
Register
(SFR)
Data Re-
gister
Direction
Register
Name
Data
Register
Name
Internal resources
selectable when
configured as DIO
MPU
Port
DIO Pin Group
Type
(SFR)
Location
Location
DIO_0…DIO_3
DIO 4…DIO7
DIO 8…DIO11
DIO 12…DIO15
DIO 16…DIO21
DIO only
Multi-use
Multi-use
Multi-use
Multi-use
P0
P0
P1
P1
P2
0xA2 [3:0]
0xA2 [7:4]
0x91 [3:0]
0x91[7:4]
0xA1[5:0]
0x80 [3:0]
0x80 [7:4]
0x90 [3:0]
0x90[7:4]
0xA0[5:0]
Yes
Yes
Yes
No
DIR0
P0
DIR1
DIR2
P1
P2
No
Table 51: Direction Registers and Internal Resources for DIO Pin Groups
DIO_DIR bit
0
1
DIO Pin Function
input
output
Table 52: DIO_DIR Control Bit
Page: 35 of 75
© 2006 TERIDIAN Semiconductor Corporation
REV 1.0
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
