User Manual

ams Datasheet Page 15
[v1-06] 2019-Feb-07 Document Feedback
CCS811 − Application Information
I²C Interface
I²C transactions require a register address to be selected
(written) and followed by data, as described by the transaction
types in the subsections below. Each Register location
corresponds to a byte or multiple bytes. Multiple reads or writes
in a single sequence will be to or from the same location (the
address does not increment). Therefore, registers are
sometimes referred to as mailboxes in this document.
CCS811 requires the host processor supports clock stretching.
I²C Register Write
Figure 12:
I²C Register Write
As shown above, a transaction may be:
• Single Byte to select a register address for subsequent
read
• Two Bytes to select a register address and write a byte to
it, typically to set a single-byte register value
• Multi-Bytes to select a register address and write several
bytes to it, typically to set multiple configuration bytes
SL AVE ADD RES SS W A DATA(REG ADDR)
DATA
A P
SL AVE ADD RES SS W A DATA(REG ADDR) A
PSL AVE ADD RES SS W A DATA(REG ADDR) A
P
A
A
ADATA
DATA
Write, register address only
Write value to register
Write multiple data
values to register
(mailbox)
From master to slave
From slave to master
S
Start condition
P
STOP condition
W
R
Write
Read
A
Acknowledge