Data Sheet

STMPE610 I2C interface
Doc ID 15432 Rev 4 11/56
Figure 6. Read and write modes (random and sequential)
4.3 Read operation
A write is first performed to load the register address into the Address Counter but without
sending a Stop condition. Then, the bus master sends a reStart condition and repeats the
Device Address with the R/W bit set to 1. The slave device acknowledges and outputs the
content of the addressed byte. If no additional data is to be read, the bus master must not
acknowledge the byte and terminates the transfer with a Stop condition.
If the bus master acknowledges the data byte, then it can continue to perform the data
reading. To terminate the stream of data bytes, the bus master must not acknowledge the
last output byte, and be followed by a Stop condition. If the address of the register written
into the Address Counter falls within the range of addresses that has the auto-increment
function, the data being read will be coming from consecutive addresses, which the internal
Address Counter automatically increments after each byte output. After the last memory
address, the Address Counter 'rolls-over' and the device continues to output data from the
memory address of 0x00. Similarly, for the register address that falls within a non-increment
range of addresses, the output data byte comes from the same address (which is the
address referred by the Address Counter).
Acknowledgement in read operation
For the above read command, the slave device waits, after each byte read, for an
acknowledgement during the ninth bit time. If the bus master does not drive the SDA to a
low state, then the slave device terminates and switches back to its idle mode, waiting for
the next command.
Start
R/W=0
Ack
Device
Address
Reg
Address
Ack
Restart
Device
Address
Ack
R/W=1
Data
Read
No Ack
Stop
One byte
Read
Start
R/W=0
Ack
Device
Address
Reg
Address
Ack
Restart
Device
Address
Ack
R/W=1
Data
Read
Ack
More than one byte
Read
Ack
No Ack
Stop
Data
Read + 1
Data
Read + 2
Start
R/W=0
Ack
Device
Address
Reg
Address
Ack
Data
to be
written
Ack
Stop
One byte
Write
More than one byte
Read
Start
R/W=0
Ack
Device
Address
Reg
Address
Ack
Data to
Write
Ack
Stop
Data to
Write + 2
Ack
Ack
Data to
Write + 1
Master
Slave