NRF52810-QFAA-R datasheet(259/483 Pages) NORDIC

259 / 483 page

Peripherals

Simple sequence example on page 259 depicts the source code used for configuration and timing

details in a sequence where only sequence 0 is used and only run once with a new PWM duty cycle for

each period.

NRF_PWM0->PSEL.OUT[0] = (first_pin << PWM_PSEL_OUT_PIN_Pos) |

(PWM_PSEL_OUT_CONNECT_Connected <<

PWM_PSEL_OUT_CONNECT_Pos);

NRF_PWM0->ENABLE

= (PWM_ENABLE_ENABLE_Enabled << PWM_ENABLE_ENABLE_Pos);

NRF_PWM0->MODE

= (PWM_MODE_UPDOWN_Up << PWM_MODE_UPDOWN_Pos);

NRF_PWM0->PRESCALER

= (PWM_PRESCALER_PRESCALER_DIV_1 <<

PWM_PRESCALER_PRESCALER_Pos);

NRF_PWM0->COUNTERTOP = (16000 << PWM_COUNTERTOP_COUNTERTOP_Pos); //1 msec

NRF_PWM0->LOOP

= (PWM_LOOP_CNT_Disabled << PWM_LOOP_CNT_Pos);

NRF_PWM0->DECODER

= (PWM_DECODER_LOAD_Common << PWM_DECODER_LOAD_Pos) |

(PWM_DECODER_MODE_RefreshCount << PWM_DECODER_MODE_Pos);

NRF_PWM0->SEQ[0].PTR = ((uint32_t)(seq0_ram) << PWM_SEQ_PTR_PTR_Pos);

NRF_PWM0->SEQ[0].CNT = ((sizeof(seq0_ram) / sizeof(uint16_t)) <<

PWM_SEQ_CNT_CNT_Pos);

NRF_PWM0->SEQ[0].REFRESH = 0;

NRF_PWM0->SEQ[0].ENDDELAY = 0;

NRF_PWM0->TASKS_SEQSTART[0] = 1;

COMPARE

SEQ[0].PTR

COMPARE

SEQ[0].CNT=4, SEQ[0].REFRESH=0, SEQ[0].ENDDELAY=0, LOOP.CNT=0

PWM Pulse Period

COMPARE

SEQEND[0]

SEQSTARTED[0]

SEQSTART[0]

Event/Tasks

Continues With Last Setting

Figure 51: Simple sequence example

A more complex example is shown in Example using two sequences on page 260, where LOOP.CNT>0 .

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 with address of values tables in Data RAM (pointed by SEQ[n].PTR)

and respective 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 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 example below, sequence 0 is defined with SEQ[0].REFRESH set to one - that means 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

4430_161 v1.0

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