STMPE1600

I2C features

Doc ID 16938 Rev 3

11/27

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 more 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 byte, the bus master must not acknowledge the last output byte and

follow 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, with the internal Address Counter automatically

increments after each byte output. After the last memory address, the Address Counter

'rolls-over' and the device continue to output data from the memory address of 0x00.

Similarly, for the address of register that falls within non-increment range of addresses, the

output data byte comes from the same address (which is the address pointed 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 low

state, then the slave device terminates and switches back to its idle mode, waiting for the

next command.

Write operations

A write is first performed to load the register address into the Address Counter without

sending a Stop condition. After the bus master receives an acknowledgement from the slave

device, it may start to send a data byte to the register (pointed by the Address Counter). The

slave device again acknowledges and the bus master terminates the transfer with a Stop

condition. If the bus master would like to continue to write more data, it can just continue

write operation without issuing the Stop condition. Whether the Address Counter auto

increments or not after each data byte write, depends on the address of the register written

into the Address Counter. After the bus master writes the last data byte and the slave device

acknowledges the receipt of the last data, the bus master may terminate the write operation

by sending a Stop condition. When the Address Counter reaches the last memory address,

it 'rolls-over' on the next data byte write.

General call

A general call address is a transaction with the slave address of 0x00 and R/W = 0. When a

general call address is made, the device responds to this transaction with an

acknowledgement and behaves as a slave-receiver mode. The meaning of a general call

address is defined in the second byte sent by the master-transmitter.