User Manual

BH1750FVI
Technical Note
10/17
www.rohm.com
2009.04- Rev.B
© 2009 ROHM Co., Ltd. All rights reserved.
●I
2
C Bus Access
1 ) I
2
C Bus Interface Timing chart
Write measurement command and Read measurement result are done by I
2
C Bus interface. Please refer the formally
specification of I
2
C Bus interface, and follow the formally timing chart.
2) Slave Address
Slave Address is 2 types, it is determined by ADDR Terminal
ADDR = ‘H’ ( ADDR ≧ 0.7VCC ) → “1011100“
ADDR = 'L' ( ADDR ≦ 0.3VCC ) → “0100011“
3 ) Write Format
BH1750FVI is not able to accept plural command without stop condition. Please insert SP every 1 Opecode.
ST
Slave Address
R/W
0
Ack
Opecode Ack SP
4 ) Read Format
ST
Slave Address
R/W
1
Ack
High Byte [15:8]
2
15
2
14
2
13
2
12
2
11
2
10
2
9
2
8
Ack
Low Byte [7:0]
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
Ack
SP
ex )
High Byte = "1000_0011"
Low Byte = "1001_0000"
( 2
15
+ 2
9
+ 2
8
+ 2
7
+ 2
4
) / 1.2 ≒ 28067 [ lx ]
* I
2
C BUS is trademark of Phillips Semiconductors. Please refer formality specification.
from Master to Slave
from Slave to Master
t
HD ; DAT
S
SDA
SCL
S
t
HD ; STA
t
LOW
t
f
t
r
t
Sr
t
SU ; STA
t
SU ; DAT
t
f
tHD
t
SU;STO
t
BUF
S
P
t
r
S
t
HIGH
t
HD ; STA