- MAX7219 is an integrated serial input/output common-cathode display driver. It connects to a microprocessor and an 8-digit 7-segment LED display, and can also drive a bar graph display or 64 independent LEDs. It includes an on-chip B-type BCD encoder, multi-channel scanning loop, segment word driver, and an 8x8 static RAM for storing each data. Only one external register is used to set the segment current of each LED. - Design and interface - A convenient four-wire serial interface can be connected to all general-purpose microprocessors. Each data item can be addressed without updating all displays, and users can choose to encode or not encode each data. - The device includes a 150 microampere low-power shutdown mode, analog and digital brightness control, a scan limit register to display 1-8 bits of data, and a detection mode that allows all LEDs to emit light. - Specifications - A single module can drive an 8x8 common-cathode dot matrix. - Module operating voltage: 5V. - Module size: 12.8 cm (length) x 3.2 cm (width) x 1.3 cm (height). - 64 fixing screw holes, 3 mm diameter. - Module includes input and output interfaces and supports multiple modules cascading. - Only 3 IO ports are needed to drive one dot matrix; no flashing when the dot matrix is displayed; supports cascading. - Wiring and cascading - The left side of the module is the input port, and the right side is the output port. - For a single module, connect the input port to the CPU. - For cascading multiple modules, connect the output of the first module to the input of the second module, the output of the second module to the input of the third, and so on.