Interface circuit between 51 single chip microcomputer and MAX7219

The following figure shows the connection diagram of 51 series single-chip microcomputer 89C2O5l and MAX7219. For convenience, only one common cathode digital tube U3 is drawn in the figure. The connection of the other seven common cathode digital tubes is the same. P1.7, P1.6, and P1.5 in the P1 port of the single-chip microcomputer 89C2O5l are connected to the DIN, CLK, and LOAD of the MAX7219 respectively. The segment outputs A~F of the MAX7219 are connected to the A~F of the common cathode digital tube respectively. The bit driver DIGO is connected to the ground terminals 3 and 8 of the digital tube.