def mavlink_packet(self, m):
        '''handle a mavlink packet'''
        mtype = m.get_type()
        if mtype == "SYS_STATUS":
            self.battery_update(m)
        if mtype == "BATTERY2":
            self.battery2_voltage = m.voltage * 0.001
        if mtype == "POWER_STATUS":
            self.power_status_update(m)
        if self.battery_period.trigger():
            self.battery_report()
handle a mavlink packet