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LED Dot Matrix
The LED dot matrix can be divided into two types: Common Cathode (CC) and Common Anode (CA). They look similar on the outside, but their internal electrical structure is different.
The LED dot matrix used in this kit is a Common Anode (CA) type. You can identify it by the marking “788BS” printed on the side of the module.
Pin Layout
The pins are located on both sides of the back of the module. When facing the side with the label:
Pins 1–8 are on one side
Pins 9–16 are on the opposite side
External view:
Internal Structure
The following figure shows the internal structure of the LED dot matrix.
In a Common Anode (CA) matrix, ROW = Anode and COL = Cathode
In a Common Cathode (CC) matrix, ROW = Cathode and COL = Anode
For both CA and CC types, the physical pin positions for rows and columns are the same — only the electrical polarity is different.
Pin Mapping
COL |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
|---|---|---|---|---|---|---|---|---|
Pin No. |
13 |
3 |
4 |
10 |
6 |
11 |
15 |
16 |
ROW |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Pin No. |
9 |
14 |
8 |
12 |
1 |
7 |
2 |
5 |
How LEDs Are Turned On
To control a single LED, you must activate its ROW and COL pins correctly.
Example: top-left LED (ROW 1, COL 1)
CA type Set ROW pin 9 = High, COL pin 13 = Low
CC type Set COL pin 13 = High, ROW pin 9 = Low
Example: light up the entire first column
CA type Set COL pin 13 = Low Set ROW pins 9, 14, 8, 12, 1, 7, 2, 5 = High
CC type Set COL pin 13 = High Set ROW pins 9, 14, 8, 12, 1, 7, 2, 5 = Low
This row-column scanning method allows you to control each LED individually using multiplexing.