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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

Serial-Addressing Format

The AS1118 contains a 16bit SPI interface to access the internal data and control registers of the device (see Digit-

and Control-Registers on page 9). The SPI interface is driven with the rising edge of SCL. A falling edge on LD signal

indicates the beginning of an access on the SPI interface, the rising edge on LD determines an access on SPI. An

access must consist of exactly 16bits for write operation and 8bits for read operation. Timing restrictions on the SPI

interface pins are defined in Figure 18.

Table 7 shows the structure of the 16bit command word for writing data, Table 8 the 8bit command word for read oper-

ation.

D0 (write operation) / D8 (read operation) is the first bit to shift into the SPI interface after the falling edge of LD, is the

last bit to write to SPI before rising edge of LD.

At a read operation an 8bit operation is executed. At the first rising edge of SCL after the rising edge of LD D7 of

addressed register is written to SDO pin. At the next rising edge of SCL D6 is written to SDO pin. LD must be kept high

during reading data from a internal data or control register of AS1118.

Figure 17. Read operation

Figure 18. Interface Timing

Initial Power-Up

On initial power-up, the AS1118 registers are reset to their default values, the display is blanked, and the device goes

into shutdown mode. At this time, all registers should be programmed for normal operation.

Note: The default settings enable only scanning of one digit; the internal decoder is disabled and the Intensity Control

Register (see page 13) is set to the minimum values.

Table 7. 16-Bit Serial Data Format

D0

D1

D2

D3

D4

D5

D6

D7

D8

D9

D10

D11

D12

D13

D14

D15

LSB

Data

MSB

Register Address (see Table 8)

0

R/W

X

1

9

8

10

16

D4

D3

D2

D1

D0

D6

D5

D7

SCL

LD

SDO

LD

SCL

SDI

SDO

D0

D1

D14

D15