Philips Semiconductors
Product specification
4-digit LED-driver with I
2
C-Bus interface
Status byte
SAA1064
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:
SC
0
0
0
0
1
1
1
1
SB
0
0
1
1
0
0
1
1
SA
0
1
0
1
0
1
0
1
SUB-ADDRESS
00
01
02
03
04
05
06
07
FUNCTION
control register
digit 1
digit 2
digit 3
digit 4
reserved, not used
reserved, not used
reserved, not used
Control bits
(see Fig.4)
The control bits C0 to C6 have the following meaning:
C0 = 0
C0 = 1
C1 = 0/1
C2 = 0/1
C3 = 1
C4 = 1
C5 = 1
C6 = 1
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.
static mode, i.e. continuous display of digits 1 and 2
dynamic mode, i.e. alternating display of digit 1 + 3 and 2 + 4
digits 1 + 3 are blanked/not blanked
digits 2 + 4 are blanked/not blanked
all segment outputs are switched-on for segment test
(1)
adds 3 mA to segment output current
adds 6 mA to segment output current
adds 12 mA to segment output current
February 1991
6
PHILIPS [ NXP SEMICONDUCTORS ]
