float pickup_obsrver(nonLinObs_TypeDef *p) {
    // Absolute BEMF voltage.
    float Vdq = sqrtf(SQ(*p->Var) + SQ(*p->Vbr));

    float factor = 1.0f / Vdq;

    float x1 = *p->Var * factor;
    float x2 = *p->Vbr * factor;

    float bias = -M_PI_2;

    if(*p->S < 0) {
        bias = -bias;
        Vdq = -Vdq;
    }

    m_rotf(x1, x2, bias, &p->x1, &p->x2);

    float ph = fast_atan2f(p->x2, p->x1);

    if(ph == ph) {
        p->ph = ph;
        p->x1 *= *p->l;
        p->x2 *= *p->l;
    }

    return Vdq;
}