ALS-PDIC17-57B-TR8 Datasheet, PDF (9/19 Pages) Everlight Electronics Co., Ltd – Surface - Mount I2C Digital Ambient Light Sensor

Surface - Mount
I²C Digital Ambient Light Sensor
ALS-PDIC17-57B/TR8
Communication Format
ALS-PDIC17-57B is capable of working as an I²C slave. Address of this device on I²C bus
is always 0x29 (hexadecimal number 29). Registers of the slave device can be programmed by
sending commands over I²C bus.
Figure 14 shows an I²C write operation. To write to an internal register of the slave
device a command must be sent by an I²C master. As illustrated in Figure 14, the I²C write
command begins with a start condition. After the start condition, seven bits of address are sent
with MSB going first. RD / WR_n (=Low) command bit follows the address bits. Upon receiving a
valid address the slave device responds by driving SDA low for an ACK. After receiving an ACK,
I²C master sends eight bits of data with MSB first. Upon receiving eight bits of data the slave
device generates an ACK. I²C master terminates this write command with a stop condition.
Figure 14 I²C Timing Diagram for Send Byte Format
Figure 15 shows an I²C read command sent by the master to the slave device. I²C read
command begins with a start condition. After the start condition seven bits of address are sent
by the master with MSB going first. After the address bits, RD / WR_n command bit is sent. For
a read command the RD / WR_n bits is high. Upon receiving the address bits and RD / WR_n
command bits the slave device responds with an ACK. After sending an ACK, the slave device
sends eight bits of data with MSB going first. After receiving the one byte data, the I²C master
terminates this transaction by issuing a NACK command to indicate that the master only
wanted to read one byte from the device. The master generates a stop condition to end this
transaction.
Everlight Electronics Co., Ltd.
Document No: DLS-00000xx Rev0.1
9
http://www.everlight.com
Jun. 22, 2011