Systems and methods for flow control within a Serial Peripheral Interface without additional signal lines are included herein. The password includes a day of retirement, names of G1 races won, and so on. A first diode is coupled to the sense winding, a first resistor is coupled to the first diode and a first capacitor coupled to the first resistor and the first diode. A controller selects one of the previously set character input mode and a temporary character mode, based on an input of the temporary mode conversion key, and reads out and recognizes character codes of each character types from the memory according to the plurality of keys input and the selected character input mode. The brush mandrel includes a corresponding contact surface having a spherical profile, so that the brush mandrel and the mounting assembly form a spherical joint at the point of contact. With such methods and filter elements, individual filter elements can be securely adhered in a simple manner to form a filter.