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lockin-external: add doc

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Robert Jördens 2021-02-02 15:50:31 +01:00
parent bd71136cdf
commit e423eff0e2
1 changed files with 5 additions and 16 deletions
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src/bin/lockin-external.rs
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@ -83,24 +83,13 @@ const APP: () = {
}
}
/// Main DSP processing routine for Stabilizer.
/// Main DSP processing routine.
///
/// # Note
/// Processing time for the DSP application code is bounded by the following constraints:
/// See `dual-iir` for general notes on processing time and timing.
///
/// DSP application code starts after the ADC has generated a batch of samples and must be
/// completed by the time the next batch of ADC samples has been acquired (plus the FIFO buffer
/// time). If this constraint is not met, firmware will panic due to an ADC input overrun.
///
/// The DSP application code must also fill out the next DAC output buffer in time such that the
/// DAC can switch to it when it has completed the current buffer. If this constraint is not met
/// it's possible that old DAC codes will be generated on the output and the output samples will
/// be delayed by 1 batch.
///
/// Because the ADC and DAC operate at the same rate, these two constraints actually implement
/// the same time bounds, meeting one also means the other is also met.
///
/// TODO: document lockin
/// This is an implementation of a externally (DI0) referenced PLL lockin on the ADC0 signal.
/// It outputs either I/Q or power/phase on DAC0/DAC1. Data is normalized to full scale.
/// PLL bandwidth, filter bandwidth, slope, and x/y or power/phase post-filters are available.
#[task(binds=DMA1_STR4, resources=[adcs, dacs, iir_state, iir_ch, lockin, timestamper, pll], priority=2)]
fn process(c: process::Context) {
let adc_samples = [