21.5.8 Waveform Generation

Waveforms can be generated in order to take advantage of the RTC inherent prescalers while the RTC is the only powered circuitry (Low-power mode of operation, Backup mode) or in any active mode. Entering Backup or Low-power operating modes does not affect the waveform generation outputs.

The RTC waveforms are internally routed to ADC trigger events. These events can be configured to provide several types of waveforms. The figure below illustrates the different signals available to generate the waveforms. Two different triggers can be generated at a time. The first is configured in RTC_MR.OUT0 while the second is configurable in RTC_MR.OUT1. OUT0 manages the trigger for channel AD[n:0] (where n is the higher index available (last channel)), while OUT1 manages the channel AD[n] only for specific modes. See the section "Analog to Digital Converter (ADC)" for selection of the measurement triggers and associated modes of operation.

The first selection choice sticks the associated output at 0. (This is the reset value and it can be used at any time to disable the waveform generation).

Selection choices 1 to 4 respectively select 1 Hz, 32 Hz, 64 Hz and 512 Hz.