SP_PIN_CONTROL
reg = ad_read(sc, SP_PIN_CONTROL);
ad_write(sc, SP_PIN_CONTROL, reg | INTERRUPT_ENABLE);
reg = ad_read(sc, SP_PIN_CONTROL);
ad_write(sc, SP_PIN_CONTROL, reg & ~INTERRUPT_ENABLE);
ad_write(&sc->sc_ad1848, SP_PIN_CONTROL, 0);