lx1977 Microsemi Corporation, lx1977 Datasheet - Page 12

• Manufacturer Part Number: lx1977
• Description: Smbus Ambient Light Sensor
• Manufacturer: Microsemi Corporation

Copyright © 2010
Rev. 1.0, 2010-03-25
S
1
Slave Address Wr
Register 00h and Send / Receive Byte Protocols application:
Examples of setting register 00h by using Send Byte Protocol
1
S
7
Start ADC conversion, the Send Byte Protocol could be used to simplify the communication. In Send Byte Protocol, bit 7
of the Data Byte field should be set to 1 indicating this is a direct command and this command should be put into Register
00h and executed. The example is shown in Table 17.
command code field should be set to 0 to indicate this byte is for the register address. Bit 6, 5 & 4 except for the Register
Address bits (bit 3, 2, 1 & 0) need to be set to zero also. These bits in this command are used for internal test purpose. The
detailed Write Byte / Read Byte protocols are shown below.
a Receive Byte protocol, it will send a copy of register 00 data back to the host. When it receives Read Byte protocol, it
will put register 00 data in the Data Byte field and send the data back to host. See Table 11 & Table 19 for details.
TM
Slave Address
When host wants to send control command(s) that is contained in Register 00, for example Enable / Disable ALS or
Write Byte Protocol could also be used to implement the same function but with a longer communication time.
When using Write Byte / Word protocol to send command / data to registers (including register 00h), bit 7 in
Register 00h could be read back by the host via Receive Byte protocol or Read Byte protocol. When LX1977 receives
One of the sample LX1977 settings and Send Byte protocol could be as shown below.
RANGE_SEL = 01b (0 ~ 1000 lux)
RANGE_SEL = 10b (0 ~ 5000 lux)
RANGE_SEL = 11b (0 ~ 2500 lux)
1
0
S
S
1
1
7
A
1
Note:
Slave Address
Slave Address
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
CMD_FLAG
ADC output count will be always in the range as specified in the above table. For example, if the T
set to 6.25ms, the ADC output count will be less or equal to 255
Bit 7
7
Wr
7
1
0
0
A
1
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2
CMD_FLAG
0
Wr
Wr
1
0
1
0
Bit 7
Table 20: Sample Send Byte Protocol
0
0
A
A
1
1
Table 18: Write Byte Protocol
Table 19: Read Byte Protocol
Table 17: Send Byte Protocol
0
Analog Mixed Signal Group
CMD_FLAG
CMD_FLAG
D
D
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
COUNT
COUNT
0
Bit 7
Bit 7
®
Microsemi
1
Register Address
1
00 ~ 08h
0
T
T
INT
INT
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Bit 1
1
0
= 25 ms
= 6.25 ms
Bit 0
1
Register Address
SMBus Ambient Light Sensor
1
00 ~ 08h
A
1
P
1
S
0
RODUCTION
Slave Address Rd
0
7
1023
255
1
A
1
D
ATASHEET
1
Data Byte
1
1
A
A
1
8
1
A
1
P
P
1
1
Data Byte
A
8
LX1977
P
1
Page 12
A
1
INT
is
1
P