www.austriamicrosystems.com

Revision 1.03

15 - 24

AS1115

Datasheet - D e t a i l e d D e s c r i p t i o n

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 and SEGF. 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 connected AS1115.

This command has to be done after startup or everytime the AS1115 gets disconnected from the supply. The I²C

address definition must be done with fixed connection, since I²C detection is excluded from debounce time of key reg-

isters.

Note:

A short writes a logical “1” whereas an open writes a logical “0” 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.

Table 11. No-Decode Mode Data Bits and Corresponding Segment Lines

D7

D6

D5

D4

D3

D2

D1

D0

Corresponding Segment Line

DP

A

B

C

D

E

F

G

Table 12. Self Addressing Register (Address (HEX) = 0x2D))

D7

D6

D5

D4

D3

D2

D1

D0

Factory-set IC address

X

X

XXXXX

0

User-set IC address

X

X

XXXXX

1

Table 13. LED Diagnostic Register Address

Register HEX Address

Segment

Key

D7

D6

D5

D4

D3

D2

D1

D0

0x1C

KEYA

DP

A

B

C

D

E

F

G

0x1D

KEYB