NRF52811-QCAA-R7 datasheet(153/444 Pages) NORDIC

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Peripherals

COMPARE

SEQ[0].PTR

SEQ[0].CNT=2, SEQ[1].CNT=3, SEQ[0].REFRESH=1, SEQ[1].REFRESH=0, SEQ[0].ENDDELAY=1, SEQ[1].ENDDELAY=0, LOOP.CNT=1

PWM clock period

COMPARE

LOOPSDONE

SEQEND[0]

SEQSTARTED[0]

SEQSTART[0]

Event/Tasks

SEQ[1].PTR

COMPARE

Event/Tasks

1 PWM period

SEQ[0].ENDDELAY=1

PWM generation maintains

last played value

(continuation)

(continued below)

SEQEND[1]

SEQSTARTED[1]

Figure 52: Example using two sequences

In this case, an automated playback takes place, consisting of SEQ[0], delay 0, SEQ[1], delay 1, then again

SEQ[0], etc. The user can choose to start a complex playback with SEQ[0] or SEQ[1] through sending the

SEQSTART[0] or SEQSTART[1] task. The complex playback always ends with delay 1.

The two sequences 0 and 1 are defined by the addresses of value tables in RAM (pointed to by

SEQ[n].PTR) and the buffer size (SEQ[n].CNT). The rate at which a new value is loaded is defined

individually for each sequence by SEQ[n].REFRESH. The chaining of sequence 1 following the sequence 0 is

implicit, the LOOP.CNT register allows the chaining of sequence 1 to sequence 0 for a determined number

of times. In other words, it allows to repeat a complex sequence a number of times in a fully automated

way.

In the following code example, sequence 0 is defined with SEQ[0].REFRESH set to 1, meaning that a

new PWM duty cycle is pushed every second PWM period. This complex sequence is started with the

SEQSTART[0] task, so SEQ[0] is played first. Since SEQ[0].ENDDELAY=1 there will be one PWM period delay

between last period on sequence 0 and the first period on sequence 1. Since SEQ[1].ENDDELAY=0 there

is no delay 1, so SEQ[0] would be started immediately after the end of SEQ[1]. However, as LOOP.CNT is

4454_140 v1.0

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