ALS-PDIC17-57B-TR8_15 Datasheet, PDF (10/21 Pages) Everlight Electronics Co., Ltd – Digital Ambient Light Sensor

DATASHEET
SMD  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
of data with MSB going
the slave device responds with an
first. After receiving the one byte
ACK.
data,
After sending an ACK, the
the I²C master terminates
slave device sends
this transaction by
eight bits
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.
Figure 15 I²C Timing Diagram for Receive Byte Format
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