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AS1117

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 8 key readback nodes can be left open or shorted for self-addressing. This is done with

KEY 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 AS1117.

This command has to be done after startup or everytime the AS1117 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 “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 8 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 KEY 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.

X

0

0

1

1

X

10

01

X

11

11

X

0

1

0

0

X

10

10

1

*

XX

X

X

X

X

0

1

0

1

X

10

11

*

The decimal point can be enabled with every character by setting bit D7 = 1.

Table 12. 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 13. Self Addressing Register (Address (HEX) = 0x2D))

D7

D6

D5

D4

D3

D2

D1

D0

Factory-set IC address

XX

XXXXX

0

User-set IC address

X

X

XXXXX

1

Table 14. LED Diagnostic Register Address

Register HEX Address

Segment

D7

D6

D5

D4

D3

D2

D1

D0

0x1C

KEY

DP

A

B

C

D

E

F

G

Table 11. HEX Font

Char-

acter

Register Data

Char-

acter

Register Data

Char-

acter

Register Data

D7 D6:D4 D3 D2 D1 D0

D7 D6: D4 D3 D2 D1 D0

D7

D6:D4

D3 D2 D1 D0