sl-firmware
34a003d0b1
Implements STM32F7 non-blocking driver for HC-SR04 ultrasonic ranger with TIM1 input capture. Supports distance measurement via echo pulse width analysis. Features: - Trigger: PA0 GPIO output (10µs pulse) - Echo: PA1 TIM1_CH2 input capture (both edges) - TIM1 configured for 1MHz clock (1µs per count) - Distance range: 20-5000mm (±3mm accuracy) - Distance = (pulse_width_us / 2) / 29.1mm - Non-blocking API with optional callback - Timeout detection (30ms max echo wait) - State machine: IDLE → TRIGGERED → MEASURING → COMPLETE/ERROR API Functions: - ultrasonic_init(): Configure GPIO and TIM1 - ultrasonic_trigger(): Start measurement - ultrasonic_set_callback(): Register completion callback - ultrasonic_get_state(): Query current state - ultrasonic_get_result(): Retrieve measurement result - ultrasonic_tick(): Periodic timeout handler Test Suite: - 26 passing unit tests - Distance conversion accuracy (100mm-2000mm) - State machine transitions - Range validation (20-5000mm boundaries) - Timeout detection - Multiple sequential measurements Integration: - ultrasonic_init() called in main() startup after servo_init() - Non-blocking operation suitable for autonomous navigation/obstacle avoidance Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
102 lines
3.2 KiB
C
102 lines
3.2 KiB
C
#ifndef ULTRASONIC_H
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#define ULTRASONIC_H
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#include <stdint.h>
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#include <stdbool.h>
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/*
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* ultrasonic.h — HC-SR04 ultrasonic distance sensor driver (Issue #243)
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*
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* STM32F722 driver for HC-SR04 ultrasonic ranger with TIM1 input capture.
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* Trigger: PA0 (GPIO output, active high pulse 10µs)
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* Echo: PA1 (TIM1_CH2, input capture on rising/falling edges)
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*
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* Non-blocking operation: trigger measurement, get result via callback.
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* Distance calculated from echo pulse width: distance_mm = (pulse_us / 2) / 29.1
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* Typical range: 20-4000mm (accuracy ±3mm above 30mm)
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*/
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/* Ultrasonic sensor states */
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typedef enum {
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ULTRASONIC_IDLE, /* Ready for new measurement */
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ULTRASONIC_TRIGGERED, /* Trigger pulse sent, waiting for echo */
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ULTRASONIC_MEASURING, /* Echo rising edge detected, measuring */
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ULTRASONIC_COMPLETE, /* Measurement complete */
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ULTRASONIC_ERROR /* Timeout or out-of-range */
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} UltrasonicState;
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/* Measurement result callback: called when measurement completes
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* Arguments:
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* - distance_mm: measured distance in mm (0 if error/timeout)
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* - is_valid: true if measurement valid, false if timeout/error
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*/
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typedef void (*ultrasonic_callback_t)(uint16_t distance_mm, bool is_valid);
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/*
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* ultrasonic_init()
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*
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* Initialize HC-SR04 driver:
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* - PA0 as GPIO output (trigger pin)
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* - PA1 as TIM1_CH2 input capture (echo pin)
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* - Configure TIM1 for input capture on both edges (rising/falling)
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* - Enable timer interrupt for echo measurement
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*/
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void ultrasonic_init(void);
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/*
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* ultrasonic_trigger()
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*
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* Start a non-blocking distance measurement.
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* Sends 10µs trigger pulse on PA0, sets up echo measurement.
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* Measurement completes asynchronously (typically 25-300ms depending on distance).
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* Call ultrasonic_get_state() to check status or wait for callback.
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*
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* Returns: true if triggered successfully, false if still measuring previous result
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*/
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bool ultrasonic_trigger(void);
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/*
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* ultrasonic_set_callback(callback)
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*
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* Register callback to be called when measurement completes.
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* Callback receives: distance_mm (0 if error), is_valid (true if successful)
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* Callback is optional; can poll with ultrasonic_get_result() instead.
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*/
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void ultrasonic_set_callback(ultrasonic_callback_t callback);
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/*
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* ultrasonic_get_state()
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*
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* Returns current measurement state (IDLE, TRIGGERED, MEASURING, COMPLETE, ERROR).
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* Useful for non-blocking polling.
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*/
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UltrasonicState ultrasonic_get_state(void);
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/*
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* ultrasonic_get_result(distance_mm, is_valid)
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*
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* Retrieve result of last measurement (only valid when state == ULTRASONIC_COMPLETE).
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* Resets state to IDLE after reading.
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*
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* Arguments:
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* - distance_mm: pointer to store distance in mm
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* - is_valid: pointer to store validity flag
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*
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* Returns: true if result retrieved, false if no measurement available
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*/
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bool ultrasonic_get_result(uint16_t *distance_mm, bool *is_valid);
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/*
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* ultrasonic_tick(now_ms)
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*
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* Update function called periodically (recommended: every 1-10ms in main loop).
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* Handles timeout detection for echo measurement.
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* Must be called regularly for non-blocking operation.
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*
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* Arguments:
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* - now_ms: current time in milliseconds (from HAL_GetTick() or similar)
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*/
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void ultrasonic_tick(uint32_t now_ms);
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#endif /* ULTRASONIC_H */
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