Struct FilterParameters

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pub struct FilterParameters { /* private fields */ }

Expand description

Filter parameters (order, OSR and input width) for a filter.

Implementations§

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impl FilterParameters

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pub fn new(order: FilterOrder, iosr: u16) -> Self

Create from FilterOrder (carrying its FOSR) and the actual IOSR value, assuming a 1-bit serial input. Panics if out of range. For a non-panicking variant, use FilterParameters::try_new. For parallel (ADC/DMA) inputs use FilterParameters::new_for_width.

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pub fn try_new(order: FilterOrder, iosr: u16) -> Result<Self, Error>

Try to create from the actual OSR value, assuming a 1-bit serial input. See the TRM for valid OSR and IOSR. Filter gain and total gain must each <= 2^31.

Returns Error::InvalidFilterParameters if iosr is outside 1..=256, the filter order’s FOSR is invalid, or the resulting gain exceeds the ceiling.

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pub fn new_for_width(order: FilterOrder, iosr: u16, width: InputWidth) -> Self

Create from FilterOrder, IOSR, and the effective input bit-width. Use this for parallel (ADC/DMA) inputs, where the gain ceiling is lower than for serial inputs. Panics if out of range.

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pub fn try_new_for_width( order: FilterOrder, iosr: u16, width: InputWidth, ) -> Result<Self, Error>

Try to create from the actual OSR value and the effective input bit-width. Filter gain and total gain must each fit under max_gain for the given width.

Returns Error::InvalidFilterParameters if iosr is outside 1..=256, the filter order’s FOSR is invalid, or the resulting gain exceeds the ceiling for width.

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pub fn new_ignore_gain_ceiling( order: FilterOrder, iosr: u16, ) -> Result<Self, Error>

Skips the input-width gain-ceiling check entirely. For callers who have verified their own headroom - e.g. known-small input amplitude, or downstream scaling/offset that keeps the accumulator in range regardless of the nominal filter gain.

Still validates FOSR/IOSR register range and rejects combinations where the gain calculation itself overflows u128 (garbage in, garbage out) - only the “does this fit under the input-width ceiling” check is bypassed.

Because the ceiling is skipped, the resulting gain may exceed u32::MAX. FilterParameters::total_gain truncates silently in that case (as u32) - use FilterParameters::total_gain_wide for a lossless u128 reading, and prefer it when constructing via this method.

Returns Error::InvalidFilterParameters if iosr is outside 1..=256, the filter order’s FOSR is invalid, or the gain computation itself overflows u128.

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pub fn total_gain(&self) -> u32

Returns the total gain of this filter parametrization, truncated to u32.

For instances built via new/try_new/new_for_width/ try_new_for_width, the gain is guaranteed <= i32::MAX-derived ceiling and this never truncates.

For instances built via FilterParameters::new_ignore_gain_ceiling, the true gain may exceed u32::MAX and this value silently truncates (as u32) - use FilterParameters::total_gain_wide instead in that case.

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pub fn total_gain_wide(&self) -> u128

Returns the total gain of this filter parametrization as a lossless u128, regardless of how the instance was constructed. Prefer this over FilterParameters::total_gain for instances built via FilterParameters::new_ignore_gain_ceiling.

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