MAX7301
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port I/O Expander
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Table 4. Power-Up Configuration
REGISTER DATA
REGISTER
FUNCTION
POWER-UP CONDITION
ADDRESS
CODE
HEX
D7 D6 D5 D4 D3 D2 D1
Port Register
Bits 4 to 31
GPIO Output Low
0x24 to
0x3F
XXXXXXX
Configuration
Register
Shutdown Enabled
Transition Detection Disabled
0x04
00XXXXX
Input Mask
Register
All Clear (Masked Off) 0x06
X000000
P7, P6, P5, P4: GPIO Inputs Without Pullup 0x09
1010101
P11, P10, P9, P8: GPIO Inputs Without Pullup 0x0A
1010101
P15, P14, P13, P12: GPIO Inputs Without
Pullup
0x0B
1010101
P19, P18, P17, P16: GPIO Inputs Without
Pullup
0x0C
1010101
P23, P22, P21, P20: GPIO Inputs Without
Pullup
0x0D
1010101
P27, P26, P25, P24: GPIO Inputs Without
Pullup
0x0E
1010101
P31, P30, P29, P28: GPIO Inputs Without
Pullup
0x0F
1010101
X = Unused bits; if read, zero results.
Table 5. Configuration Register Format
REGISTER DATA
FUNCTION
ADDRESS CODE
(HEX)
D7 D6 D5 D4 D3 D2 D1 D0
Table 6. Shutdown Control (S Data Bit D0) Format
REGISTER DATA
FUNCTION
ADDRESS CODE
(HEX)
D7 D6 D5 D4 D3 D2 D1 D0
Shutdown 0x04 M 0 XXXXX0
Normal Operation 0x04 M 0 XXXXX1
