NRF52810-QFAA-R datasheet(253/483 Pages) NORDIC

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Peripherals

given PWM period. A COUNTERTOP value smaller than the compare setting will result in a state where no

PWM edges are generated. Respectively, OUT[n] is held high, given that the polarity is set to FallingEdge.

All the compare registers are internal and can only be configured through the decoder presented later.

COUNTERTOP can be safely written at any time. It will get sampled following a START task. If

DECODER.LOAD is anything else than WaveForm, it will also get sampled following a STARTSEQ[n] task,

and when loading a new value from RAM during a sequence playback. If DECODER.LOAD=WaveForm, the

PWM up counter example - FallingEdge polarity on page 254 shows the counter operating in up

(MODE=PWM_MODE_Up) mode with three PWM channels with the same frequency but different duty

cycle. The counter is automatically reset to zero when COUNTERTOP is reached and OUT[n] will invert.

OUT[n] is held low if the compare value is 0 and held high respectively if set to COUNTERTOP given that

the polarity is set to FallingEdge. Running in up counter mode will result in pulse widths that are edge-

aligned. See the code example below:

uint16_t pwm_seq[4] = {PWM_CH0_DUTY, PWM_CH1_DUTY, PWM_CH2_DUTY, PWM_CH3_DUTY};

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

(PWM_PSEL_OUT_CONNECT_Connected <<

PWM_PSEL_OUT_CONNECT_Pos);

NRF_PWM0->PSEL.OUT[1] = (second_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_Individual << PWM_DECODER_LOAD_Pos) |

(PWM_DECODER_MODE_RefreshCount << PWM_DECODER_MODE_Pos);

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

NRF_PWM0->SEQ[0].CNT = ((sizeof(pwm_seq) / 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;

4430_161 v1.0

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NRF52810-QFAA-R Datasheet(PDF) 253 Page - Nordic Semiconductor