MAX6955_15 Datasheet, PDF (30/40 Pages) Maxim Integrated Products – 2-Wire Interfaced, 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan

MAX6955
2-Wire Interfaced, 2.7V to 5.5V
LED Display Driver with I/O
Expander and Key Scan
Table 33. Port Configuration Register Format
MODE
ADDRESS
CODE (HEX)
D7
D6
D5
GPIO
Configuration
0x06
Set number of keys scanned
Register
PORT ALLOCATION OPTIONS
0 Keys Scanned
0x06
0
0
0
8 Keys Scanned
0x06
0
0
1
16 Keys Scanned
0x06
0
1
0
24 Keys Scanned
0x06
0
1
1
32 Keys Scanned
0x06
1
X
X
EXAMPLE PORT CONFIGURATION SETTINGS
No Keys
Scanned, P4 and
P2 Are Outputs,
0x06
0
0
0
Others Are Inputs
8 Keys Scanned,
P3 and P1 Are
Outputs, P2 Is an
0x06
0
1
0
Input
32 Keys
Scanned, No
0x06
1
X
X
GPIO Ports
REGISTER DATA
D4
D3
D2
D1
Set port direction for ports P0 to P4:
0 = output, 1 = input
P4
P3
P2
P1
IRQ
P3
P2
P1
IRQ
P3
P2
Key_B
IRQ
P3
Key_C Key_B
IRQ
Key_D Key_C Key_B
0
1
0
1
X
0
1
0
X
X
X
X
D0
P0
Key_A
Key_A
Key_A
Key_A
1
X
X
Table 34. Key Mask Register Format (Write Only)
KEY
MASK
REGISTER
Key_A Mask
Register
Key_B Mask
Register
Key_C Mask
Register
Key_D Mask
Register
ADDRESS
CODE
(HEX
0x08
D7
SW_A7
REGISTER DATA
WITH APPROPRIATE SWITCH NAMED BELOW
D6
D5
D4
D3
D2
D1
SW_A6 SW_A5 SW_A4 SW_A3 SW_A2 SW_A1
0x09
SW_B7 SW_B6 SW_B5 SW_B4 SW_B3 SW_B2 SW_B1
0x0A
SW_C7 SW_C6 SW_C5 SW_C4 SW_C3 SW_C2 SW_C1
0x0B
SW_ D7 SW_D6 SW_D5 SW_D4 SW_D3 SW_D2 SW_D1
D0
SW_A0
SW_B0
SW_C0
SW_D0
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