15. Low Duty-Cycle Command

Configures periodic receiver operation to reduce average power consumption. The receiver wakes briefly to check for an FSK transmission and extends its on-time while the Data Quality Detector (DQD) indicates a good signal.

Register Fields

Bits

Name

Meaning

API

7:1

d6:d0

Duty-cycle parameter D

rfm12_set_low_duty_cycle_d()

0

en

Low duty-cycle enable

rfm12_set_low_duty_cycle_enable()

The setters listed in the register field table above directly configure fields in the Low Duty-Cycle Command. The setters and reset function update staged configuration without communicating with the radio. Use rfm12_apply_to_radio() to write the staged settings.

The Wake-Up Timer Command determines the cycle period. The nominal duty cycle is (2 * D + 1) / M * 100%, where M is the wake-up timer multiplier configured by rfm12_set_wakeup_timer(). This calculation requires a nonzero multiplier.

Note

Low duty-cycle operation requires er to be cleared and ew to be set in the Power Management Command. Stage these settings with rfm12_set_receiver_enable() and rfm12_set_wakeup_timer_enable(), respectively, and apply them along with the duty-cycle configuration. The radio does not generate wake-up timer interrupts in this mode.

Allow enough receiver on-time for the crystal oscillator, synthesizer, and PLL to start and for DQD to recognize valid data. An on-time that is too short can prevent reception even when the incoming signal is good.

Command Functions

rfm12_set_low_duty_cycle_d()

RFM12_result_t rfm12_set_low_duty_cycle_d(RFM12_t *dev, RFM12_low_duty_cycle_d_t d)

Stage the low duty-cycle parameter D.

The setter accepts values from 0 through 127. Pass the raw D field, not a percentage; the resulting duty cycle also depends on the wake-up timer multiplier M.

Parameters:

  • dev – RFM12 radio instance.

  • d – Duty-cycle parameter D, from 0 through 127.

Returns:

RFM12_OK on success, or an appropriate RFM12_result_t error.

rfm12_set_low_duty_cycle_enable()

RFM12_result_t rfm12_set_low_duty_cycle_enable(RFM12_t *dev, RFM12_enable_t enable)

Stage the low duty-cycle enable setting.

The wake-up timer and Power Management Command settings must also be configured for periodic receiver operation as described above.

Parameters:

  • dev – RFM12 radio instance.

  • enable – Enable or disable low duty-cycle operation.

Returns:

RFM12_OK on success, or an appropriate RFM12_result_t error.

rfm12_reset_low_duty_cycle()

RFM12_result_t rfm12_reset_low_duty_cycle(RFM12_t *dev)

Reset the staged Low Duty-Cycle Command values to their defaults.

This function does not communicate with the radio. The changed settings are written to the radio by rfm12_apply_to_radio().

Parameters:

  • dev – RFM12 radio instance.

Returns:

RFM12_OK on success, or an appropriate RFM12_result_t error.