MAX6955 Maxim, MAX6955 Datasheet - Page 30

• Manufacturer Part Number: MAX6955
• Description: 2-Wire Interfaced / 2.7V to 5.5V LED Display Driver with I/O Expander and Key Scan
• Manufacturer: Maxim

2-Wire Interfaced, 2.7V to 5.5V LED Display
Driver with I/O Expander and Key Scan
Table 33. Port Configuration Register Format
Table 34. Key Mask Register Format (Write Only)
30
GPIO
Configuration
Register
PORT ALLOCATION OPTIONS
0 Keys Scanned
8 Keys Scanned
16 Keys Scanned
24 Keys Scanned
32 Keys Scanned
EXAMPLE PORT CONFIGURATION SETTINGS
No Keys
Scanned, P4 and
P2 Are Outputs,
Others Are Inputs
8 Keys Scanned,
P3 and P1 Are
Outputs, P2 Is an
Input
32 Keys
Scanned, No
GPIO Ports
Key_C Mask
Key_D Mask
Key_A Mask
Key_B Mask
REGISTER
Register
Register
Register
Register
______________________________________________________________________________________
MASK
KEY
MODE
ADDRESS
CODE
(HEX
0x08
0x09
0x0A
0x0B
CODE (HEX)
ADDRESS
0x06
0x06
0x06
0x06
0x06
0x06
0x06
0x06
0x06
SW_ D7
SW_C7
SW_A7
SW_B7
D7
Set number of keys scanned
D7
0
0
0
0
1
0
0
1
SW_A6
SW_B6
SW_C6
SW_D6
D6
D6
X
X
0
0
1
1
0
1
WITH APPROPRIATE SWITCH NAMED BELOW
SW_C5
SW_D5
SW_A5
SW_B5
D5
D5
X
X
0
1
0
1
0
0
SW_C4
SW_D4
SW_A4
SW_B4
REGISTER DATA
D4
Set port direction for ports P0 to P4:
0 = output, 1 = input
REGISTER DATA
IRQ
IRQ
IRQ
IRQ
D4
P4
0
X
X
SW_A3
SW_B3
SW_C3
SW_D3
D3
Key_D
D3
P3
P3
P3
P3
X
1
0
SW_A2
SW_B2
SW_C2
SW_D2
Key_C
Key_C
D2
D2
P2
P2
P2
0
1
X
SW_A1
SW_B1
SW_C1
SW_D1
Key_B
Key_B
Key_B
D1
D1
P1
P1
X
1
0
SW_C0
SW_D0
SW_A0
SW_B0
Key_A
Key_A
Key_A
Key_A
D0
D0
P0
1
X
X