应该是任意时间的绝对定高误差100m
MS5611的相对误差小于10cm

上一个万户3号使用的气压开伞程序
原作者Shadow_Swirl大神,论坛ID = clyce
在万户3项目中使用，经过本人修改


APPALT.rar 16.46KB RAR 44次下载

void appalt_init(void);
//start pressure altimeter controlled parachute
void appalt_set_zero(void);
//set relative altitude to zero
void appalt_set_pressure(uint32_t p);// p is pressure in Pa
//input current pressure data
void appalt_set_callback(void (*f)(void));
//set parachute open function callback

核心代码：
void appalt_set_pressure(uint32_t p) {
    int pprev;
    pprev = pres;
    if ((p <= MAX_PRES) && (p >= MIN_PRES) ) {
        pres = p;
    }
    if (pres_not_setted) {pres_not_setted = 0;}
    if (p > pprev) {
        falling += 1;
    } else {
        falling = 0;
    }
    if (falling >= falling_count_th) {
        get_alt();
        if (altitude <= alt_limit) {
            // code to open the parachute
            if(f_open_parachute)
                (*f_open_parachute)();
        }
    }
}