February 1991

6

Philips Semiconductors

Product specification

SAA1064

Status byte

Only one bit is present in the status byte, the POWER RESET flag. A logic 1 indicates the occurence of a power failure

since the last time it was read out. After completion of the READ action this flag will be set to logic 0.

Subaddressing

The bits SC, SB and SA form a pointer and determine to which register the data byte following the instruction byte will

be written. All other bytes will then be stored in the registers with consecutive subaddresses. This feature is called

Auto-Increment (AI) of the subaddress and enables a quick initialization by the master.

The subaddress pointer will wrap around from 7 to 0.

The subaddresses are given as follows:

Control bits (see Fig.4)

The control bits C0 to C6 have the following meaning:

Note

1. At a current determined by C4, C5 and C6.

Data

A segment is switched ON if the corresponding data bit is logic 1. Data bits D17 to D10 correspond with digit 1, D27 to

D20 with digit 2, D37 to D30 with digit 3 and D47 to D40 with digit 4.

The MSBs correspond with the outputs P8 and P16, the LSBs with P1 and P9. Digit numbers 1 to 4 are equal to their

subaddresses (hex) 1 to 4.

SC

SB

SA

SUB-ADDRESS

FUNCTION

0

0

0

00

control register

0

0

1

01

digit 1

0

1

0

02

digit 2

0

1

1

03

digit 3

1

0

0

04

digit 4

1

0

1

05

reserved, not used

1

1

0

06

reserved, not used

1

1

1

07

reserved, not used

C0 = 0

static mode, i.e. continuous display of digits 1 and 2

C0 = 1

dynamic mode, i.e. alternating display of digit 1 + 3 and 2 + 4

C1 = 0/1

digits 1 + 3 are blanked/not blanked

C2 = 0/1

digits 2 + 4 are blanked/not blanked

C3 = 1

C4 = 1

adds 3 mA to segment output current

C5 = 1

adds 6 mA to segment output current

C6 = 1

adds 12 mA to segment output current