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AS1115
Datasheet - Detailed Description
I2C Self Addressing
If this feature is used, 2 of the 16 key readback nodes can be left open or shorted for self-addressing. This is done with
KEYA together with SEGG (A0) and SEGF (A1). This two nodes cannot be used for key-readback in this case. After
startup all devices have the predefined adress 0000000. A single command for selfaddressing will update all con-
nected AS1115. This command has to be done after startup or everytime the AS1115 gets disconnected from the sup-
ply. The I2C address definition must be done with fixed connection, since I2C detection is excluded from debounce time
of key registers.
Note:
A short writes a logical “0” whereas an open writes a logical “1” as address bit.
Keyscan Register
These two registers contain the result of the keyscan input of the 16 keys. To ensure proper results the data in these
registers are updated only if the logic data scanned is stable for 20ms (debounce time). A change of the data stored
within these two registers is indicated by a logic low on the IRQ pin. The IRQ is high-impedance if a read operation on
the key scan registers is started.
Note:
If I2C self addressing is used segment G&F of KEYA is used for the two LSB of the I2C address. In this case
these two nodes cannot be used as a key. Additionally the debounce time is disabled for these two bits.
The data within the keyscan register is updated continuously during every cycle (1/10 of refresh rate). There-
fore, to get a valid readback of keys it is recommended to read out the keyscan registers immediately after the
IRQ is triggered. A short writes a logical “0” whereas an open writes a logical “1” as keyscan register bit.
Note:
If the blink_en bit (bit D4 in the Feature Register 0x0E) is set to ‘1’, the keyscan is not returning a valid value.
Table 11. No-Decode Mode Data Bits and Corresponding Segment Lines
D7
DP
D6
A
D5
B
D4
C
D3
D
D2
E
D1
F
D0
G
Corresponding Segment Line
Table 12. Self Addressing Register (Address (HEX) = 0x2D))
D7
X
X
D6
X
X
D5
X
X
D4
X
X
D3
X
X
D2
X
X
D1
X
X
D0
0
1
Factory-set IC address
User-set IC address
Table 13. LED Diagnostic Register Address
Register HEX Address
Segment
D4
Key
KEYA
KEYB
D7
D6
D5
D3
D2
D1
D0
0x1C
0x1D
DP
A
B
C
D
E
F
G