Digital circuit experiment three:

Through experiments, the input condition bits of specific points of the LED dot matrix are obtained: the row input is valid at high level, and the column input is valid at low level. The top is the row input port, which corresponds to rows 1 to 16 from left to right. The right is the column input port, from From bottom to top corresponds to 1~16. Some experimental pictures are shown below:

ROW=1,COL1=0:

ROW=4,COL9=0:

LED dot matrix drive schematic diagram:

LED dot matrix function test circuit design - design circuit to test whether all light source points of 16*16 dot matrix are normal or not

The circuit diagram is shown below:

Since the DIP and 74LS138 have 8 outputs, we connect two inputs to one port in sequence, so that one DIP controls two rows and one output of 138 controls two columns.

The experimental diagram is as follows:

74LS197 receives 10kHz pulse.

The DIP switch is 11111111:

Because the column scanning frequency is very high, it appears to be constantly bright.

The DIP switch is 00000000:

LED dot matrix function display circuit design - design of "medium" and "large" character display circuit

Design: Column scanning still connects to 74ls138, so a NAND gate is used to select which columns of a certain row will light up when scanned.

For example, for Chinese characters, the third and fifth rows light up when columns 2, 3, 4, 5, and 6 are lit, so it can be implemented with a five-input NAND gate (built with a four-input NAND gate + a two-input AND gate) .

Rows 2, 6, and 7 only need the fourth column to light up, which can be achieved by using a NOT gate.

Using this method, you can build a "medium-large" display circuit.

The circuit diagram is as follows: (The combinational logic gates with 00, 99, 77, aa, and bb as outputs and the bottom display dot matrix belong to the next experiment)

The experimental diagram is as follows:

LED dot matrix function display circuit design - design personalized content display circuit

Our team tried to design and implement a circuit that displays smiling faces and crying faces in an 8x8 LED dot matrix cycle. This is actually equivalent to a combination of two static scans, and then using a 1Hz clock signal to control the switching of the two static scans.

It can be seen from the dot matrix diagram of the smiling face and the crying face: the difference between the two faces is in the sixth and eighth rows, which are just reversed: the smiling face has the 4th and 5th columns of the eighth row lit, while the crying face The 4th and 5th rows of the sixth row light up; the smiling face lights up at the 6th row and 2nd and 7th columns, while the crying face lights up at the 8th row and 2nd and 7th columns. So for the input of these two lines, we can design the following circuit, which connects 1Hz pulses. When connected in this way, a smiling face will be displayed when the level is high, and a crying face will be displayed when the level is low.

The complete circuit diagram is shown below:

The experimental results are as follows:

Digital circuit experiment three:

Digital Circuit Experiment ReportThree

Software Engineering Institute

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