User Manual

104
Lesson 15 Driving Dot-Matrix by 74HC595
Introduction
As the name suggests, an LED dot matrix is a matrix composed of LEDs. The lighting up and
dimming of the LEDs formulate different characters and patterns.
Components
- 1 * Raspberry Pi
- 1 * Breadboard
- 2 * 74HC595
- 1 * Dot-Matrix
- Jumper wires
Principle
Dot Matrix
Generally, dot matrix can be categorized into two types: common cathode (CC) and
common anode (CA). They look much alike, but internally the difference lies. You can tell by
test. A CA one is used in this kit. You can see 788BS labeled at the side.
See the figure below. The pins are arranged at the two ends at the back. Take the label side
for reference: pins on this end are pin 1-8, and oh the other are pin 9-16.
The external v iew:
Below the figures show their internal structure. You can see in a CA matrix, ROW represents
the anode of the LED, and COL is cathode; it's contrary for a CC one. One thing in common:
for both types, pin 13, 3, 4, 10, 6, 11, 15, and 16 are all COL, when pin 9, 14, 8, 12, 1, 7, 2, and
5 are all ROW. If you want to turn on the first LED at the top left corner, for a CA matrix, just
set pin 9 as High and pin 13 as Low, and for a CC one, set pin 13 as High and pin 9 as Low . If
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