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AS1118

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

Display-Test Mode

The AS1118 can detect open or shorted LEDs. Readout of either open LEDs (D2=1) or short LEDs (D1=1) is possible,

as well as a OR relation of open and short (D1=D2=1). After a dignostic run bit D4 can be read to clearify if an error

occurred before reading out detailed diagnostic data.

Note: All settings of the digit- and control-registers are maintained.

LED Diagnostic Registers

These eight registers contain the result of the LED open/short test for the individual LED of each digit.

Note: If more than 2 shorts occure in the LED array, detection of individual LED fault could become limited to blocs.

Intensity Control Register (0x0A)

The brightness of the display can be controlled by digital means using the Intensity Control Registers and by analog

controlled globally for all digits, or for each digit individually. The global intensity command will write intensity data to all

four individual brightness registers, while the individual intesity command will only write to the associated individual

intensity register.

Table 14. Testmode Register Summary

D7

D6

D5

D4

D3

D2

D1

D0

X

REXT_short

REXT_open

LED_global

LED_test

LED_open

LED_short

DISP_test

Table 15. Testmode Register Bit Description (Address (HEX) = 0x0F))

Addr: 0x0F

Address

Bit

Bit Name

Default

Access

D7:D0

D0

DISP_test

0

W

Optical display test. (Testmode for external visual test.)

0: Normal operation; 1: Run display test (All digits are tested

independently from scan limit & shutdown register.)

D1

LED_short

0

W

Starts a test for shorted LEDs. (Can be set together with D2)

0: Normal operation; 1: Activate testmode

D2

LED_open

0

W

Starts a test for open LEDs. (Can be set together with D1)

0: Normal operation; 1: Activate testmode

D3

LED_test

0

R

Indicates an ongoing open/short LED test

0: No ongoing LED test; 1: LED test in progress

D4

LED_global

0

R

Indicates that the last open/short LED test has detected an error

0: No error detected; 1: Error detected

D5

REXT_open

0

R

D6

REXT_short

0

R

D7

0

-

Not used

Table 16. LED Diagnostic Register Address

Register

HEX

Address

Segment

Register

HEX

Address

Segment

Digit

D7

D6

D5

D4

D3 D2

D1

D0

Digit

D7

D6 D5 D4 D3 D2 D1 D0

0x14

DIG0

DP

A

B

C

D

E

F

G

0x18

DIG4

DP

A

B

C

D

E

F

G

0x15

DIG1

0x19

DIG5

0x16

DIG2

0x1A

DIG6

0x17

DIG3

0x1B

DIG7