AS1108
Datasheet - Detailed Description
Shutdown Register (0xXC)
The Shutdown Register controls AS1108 shutdown mode (see Shutdown Mode on page 9).
Table 8. Shutdown Register Format (Address (HEX) = 0xXC))
Register Data
Mode
HEX Code
D7 D6 D5 D4 D3 D2 D1 D0
Shutdown Mode,
0x00
0x80
0x01
0x81
0
1
0
1
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0
0
1
1
Reset Feature Register to Default Settings
Shutdown Mode, Feature Register Unchanged
Normal Operation,
Reset Feature Register to Default Settings
Normal Operation, Feature Register Unchanged
Decode Enable Register (0xX9)
The Decode Enable Register sets the decode mode. BCD/HEX decoding (either BCD code – characters 0:9, E, H, L,
P, and -, or HEX code – characters 0:9 and A:F) is selected by bit D2 (page 13) of the Feature Register. The Decode
Enable Register is used to select the decode mode or no-decode for each digit. Each bit in the Decode Enable Regis-
ter corresponds to its respective display digit (i.e., bit D0 corresponds to digit 0, bit D1 corresponds to digit 1 and so
on). Table 10 lists some examples of the possible settings for the Decode Enable Register bits.
Note: A logic high enables decoding and a logic low bypasses the decoder altogether.
When decode mode is used, the decoder looks only at the lower-nibble (bits D3:D0) of the data in the Digit-Registers,
disregarding bits D6:D4. Bit D7 sets the decimal point (SEG DP) independent of the decoder and is positive logic (bit
D7 = 1 turns the decimal point on). Table 10 lists the code-B font; Table 11 lists the HEX font.
When no-decode mode is selected, data bits D7:D0 of the Digit-Registers correspond to the segment lines of the
AS1108. Table 12 shows the 1:1 pairing of each data bit and the appropriate segment line.
Table 9. Decode Enable Register Format (Address (HEX) = 0xX9))
Register Data
Decode Mode
HEX Code
D7 D6 D5 D4 D3 D2 D1 D0
No decode for digits 3:0
Code-B/HEX decode for digit 0. No decode for digits 3:1
Code-B/HEX decode for digits 3:0
0x00
0x01
0xFF
X
X
X
X
X
X
X
X
X
X
X
X
0
0
1
0
0
1
0
0
1
0
1
1
Figure 11. Standard 7-Segment LED Intensity Control and Inter-Digit Blanking
A
F
B
G
C
E
D
DP
Table 10. Code-B Font
Register Data
On Segments = 1
7-Segment
Character
D7 †
D6:D4
D3
0
D2
0
D1
0
0
1
1
D0 DP †
A
1
0
1
1
0
1
B
1
1
1
1
1
0
C
1
1
0
1
1
1
D
1
0
1
1
0
1
E
1
0
1
0
0
0
F
G
0
0
1
1
1
1
0
1
2
3
4
5
X
X
X
X
X
X
0
1
0
1
0
1
1
0
0
0
1
1
0
0
0
0
0
0
0
1
0
0
0
1
www.austriamicrosystems.com/LED-Driver-ICs/AS1108
Revision 2.13
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