NRF52810-QFAA-R datasheet(430/483 Pages) NORDIC

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Peripherals

ADDR

M-1

Stretch

Figure 118: The TWI slave responding to a write command

6.24.4 Master repeated start sequence

An example of a repeated start sequence is one in which the TWI master writes two bytes to the slave

followed by reading four bytes from the slave.

This is illustrated in A repeated start sequence, where the TWI master writes two bytes followed by

reading four bytes from the slave on page 430.

It is here assumed that the receiver does not know in advance what the master wants to read, and

that this information is provided in the first two bytes received in the write part of the repeated start

sequence. To guarantee that the CPU is able to process the received data before the TWI slave starts to

reply to the read command, the SUSPEND task is triggered via a shortcut from the READ event generated

when the read command is received. When the CPU has processed the incoming data and prepared the

correct data response, the CPU will resume the transaction by triggering the RESUME task.

ADDR

Figure 119: A repeated start sequence, where the TWI master

writes two bytes followed by reading four bytes from the slave

6.24.5 Terminating an ongoing TWI transaction

In some situations, e.g. if the external TWI master is not responding correctly, it may be required to

terminate an ongoing transaction.

This can be achieved by triggering the STOP task. In this situation a STOPPED event will be generated when

the TWI has stopped independent of whether or not a STOP condition has been generated on the TWI bus.

The TWI slave will release the bus when it has stopped and go back to its IDLE state.

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