max7219 8digit arduino max 7219 counter speed number 7 segment led

MAX7219 is a kind of integrated serial input/output common cathode display driver, it connects microprocessor and 8 digit 7 period of digital LED display, also can be connected to the bar graph display or 64 independent LED. It includes a piece of type B BCD coder, multiple scanning circuit, period of word drive, but also an 8 * 8 static RAM used to store every data. Only an external register used to set each LED segment current.