clamp-debounce v0.1.0

Limit each step, then accept a value only after N stable samples.

Application scenarios

• A slow analog channel is disturbed by spikes and single-sample drift.
• A battery voltage must not change the displayed level on one bad reading.
• A remote measurement arrives with occasional outliers.

Contract

void clamp_debounce_init(clamp_debounce_t *filter, uint16_t initial, uint16_t max_delta, uint16_t threshold);
uint16_t clamp_debounce_step(clamp_debounce_t *filter, uint16_t sample);

• max_delta caps the change from the accepted value.
• A clamped value must repeat threshold times before it is accepted.
• threshold = 0 accepts immediately.
• No allocation.

Parameters

• max_delta: largest plausible change per sample.
• threshold: number of consistent clamped samples; 3..5 is typical.
• Larger threshold: more rejection, more delay.

Memory and timing

• 10 bytes of state; O(1) per sample.

Integration

clamp_debounce_t filter;
clamp_debounce_init(&filter, 1000, 10, 3);
uint16_t value = clamp_debounce_step(&filter, adc_read());

When not to use

• A fast control loop; the clamp and count add delay.
• Only spike rejection is needed; use median.

Verification

make test covers the three-sample acceptance, release, zero threshold, and clamping.

Behavior reference: Padauk Soft_Filter/AD_filter_10.

uint16_t value;
uint16_t max_delta;
uint16_t candidate;
uint16_t threshold;
uint16_t count;