text: #ifndef __HCSR04_H
  #define __HCSR04_H
  
  #include "stdint.h"
  
  /**
   * @param gpio: gpio resource, not pin
   * @attention register fpioa first
   * @return -1: param error
   *          0: timeout
   *         >0: distance
   */
  long hcsr04_measure_cm(uint8_t trig,uint8_t echo, uint32_t timeout_us);
  long hcsr04_measure_inch(uint8_t trig,uint8_t echo, uint32_t timeout_us);
  
  
  #endif
  
  