Data Sheet AS1105

Revision 1.32, Oct. 2004

Page 7 of 12

Duty Cycle

D7 D6 D5 D4 D3 D2 D1 D0 Hex Code

1/32 (min on)

XXXX 0 0 0 0

0xX0

3/32

XXXX 0 0 0 1

0xX1

5/32

XXXX 0 0 1 0

0xX2

7/32

XXXX 0 0 1 1

0xX3

9/32

XXXX 0 1 0 0

0xX4

11/32

XXXX 0 1 0 1

0xX5

13/32

XXXX 0 1 1 0

0xX6

15/32

XXXX 0 1 1 1

0xX7

17/32

XXXX 1 0 0 0

0xX8

19/32

XXXX 1 0 0 1

0xX9

21/32

XXXX 1 0 1 0

0xXA

23/32

XXXX 1 0 1 1

0xXB

25/32

XXXX 1 1 0 0

0xXC

27/32

XXXX 1 1 0 1

0xXD

29/32

XXXX 1 1 1 0

0xXE

31/32 (max on) XXXX 1 1 1 1

0xXF

Table 7: Intensity register format (address (hex) = 0xXA)

Register Data

Scan Limit

D7

D6

D5

D4

D3

D2

D1

D0

Hex Code

Display digit 0 only

X

X

X

X

X

0

0

0

0xX0

Display digits 0 & 1

X

X

X

X

X

0

0

1

0xX1

Display digits 0 1 2

X

X

X

X

X

0

1

0

0xX2

Display digits 0 1 2 3

X

X

X

X

X

0

1

1

0xX3

Table 8: Scan-limit register format (address (hex) = 0xXB)

Display Test Register

With the display test register 0Fh all LED can be tested. In

the test mode all LEDs are switched on at maximum

brightness (duty cycle 31/32). All programming of digit and

control registers is maintained. The format of the register is

given in table 10.

Number of

Digits

Displayed

Maximum

Segment Current

(mA)

110

220

330

Table 9: Maximum segment current for 1-, 2-, or 3-digit displays

Register Data

Mode

D7 D6 D5 D4 D3 D2 D1 D0

Normal Operation XXXXXXX

0

Display Test

Mode

XXXXXXX

1

Table 10: Display-test register format (address (hex) = 0xXF)

Note: The AS1105 remains in display-test mode until the

display-test register is reconfigured for normal operation.

No-Op Register (Cascading of AS1105)

The no-operation register 00h is used when AS1105s are

cascaded in order to support more than 4 digit displays. The

cascading must be done in a way that all DOUT are

connected to DIN of the following AS1105. The LOAD and

CLK signals are connected to all devices. For a write

operation for example to the fifth device the command must

be followed by four no-operation commands.