NRF9160-SICA-R7 datasheet(294/400 Pages) NORDIC

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Peripherals

The TWI master cannot be stopped while suspended, so the STOP task must be issued after the TWI

master has been resumed.

ADDR

M-1

Stretch

Figure 92: The TWI master reading data from a slave

6.17.5 Master repeated start sequence

A typical 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 example uses shortcuts to perform the simplest type of repeated

start sequence, i.e. one write followed by one read. The same approach can be used to perform a

repeated start sequence where the sequence is read followed by write.

The following figure shows an example of a repeated start sequence where the TWI master writes two

bytes followed by reading four bytes from the slave.

ADDR

Figure 93: Master repeated start sequence

If a more complex repeated start sequence is needed, and the TWI firmware drive is serviced in a low

priority interrupt, it may be necessary to use the SUSPEND task and SUSPENDED event to guarantee that

the correct tasks are generated at the correct time. A double repeated start sequence using the SUSPEND

task to secure safe operation in low priority interrupts is shown in the following figure.

4418_1315 v2.0

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NRF9160-SICA-R7 Datasheet(PDF) 294 Page - Nordic Semiconductor