NOA3302 Datasheet, PDF (11/23 Pages) ON Semiconductor – Digital Proximity Sensor

NOA3302
Figure 22 shows an I²C read command sent by the master to the slave device. Read transactions begin in much the same
manner as the write transactions in that the slave address must be sent with a write(0) command bit.
Device
Address
A[6:0] WRITE
011 0111 0
0x6E
ACK
0
Register
Address
D[7:0] ACK
0000 0110 0
Register
Data
D[7:0] ACK
0000 0000 0
7
8
8
Start
Condition
Stop
Condition
Device
Address
A[6:0] READ
011 0111 1
0x6F
ACK
0
Register
Data [A]
D[7:0] ACK
bbbb bbbb 0
Register
Data [A+1]
D[7:0] NACK
bbbb bbbb 1
7
8
8
Start
Condition
Figure 22. I²C Read Command
Stop
Condition
After the NOA3302 sends an ACK, the master sends the
register address as if it were going to be written to. The
NOA3302 will acknowledge this as well. Next, instead of
sending data as in a write, the master will re−issue an I²C
START (repeated start) and again send the slave address and
this time the read(1) command bit. The NOA3302 will then
begin shifting out data from the register just addressed. If the
master wishes to receive more data (next register address),
it will ACK the slave at the end of the 8 bit data transmission,
and the slave will respond by sending the next byte, and so
on. To signal the end of the read transaction, the master will
send a NACK bit at the end of a transmission followed by an
I²C STOP.
The NOA3302 also supports I²C high−speed mode. The
transition from standard or fast mode to high−speed mode is
initiated by the I²C master. A special reserve device address
is called for and any device that recognizes this and supports
high speed mode immediately changes the performance
characteristics of its I/O cells in preparation for I²C
transactions at the I²C high speed data protocol rates. From
then on, standard I²C commands may be issued by the
master, including repeated START commands. When the
I²C master terminates any I²C transaction with a STOP
sequence, the master and all slave devices immediately
revert back to standard/fast mode I/O performance.
By using a combination of high−speed mode and a block
write operation, it is possible to quickly initialize the
NOA3302 I²C register bank.
http://onsemi.com
11