InetrfaceProducts NXP / PCA9622_LED8x8

Library for "I2C 8x8 LED matrix board" from Switch Science https://www.switch-science.com/catalog/2071/

Dependents:   PCA9622_LED8x8_Demo PCA9622_LED8x8_Hello PCA9622_LED8x8_x6_Demo shake-shake-machine

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Table of Contents

  1. What is this?
  2. How to use
  3. Links

What is this?

I2C interface single color LED matrix module with PCA9622(LED controller).

This library provides interface from memory array to LEDs, manages scan.
Brightness control can be done for each pixels by setting data as float value (from 0.0 to 1.0).

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How to use

Sample code is available.

Next is simplified code sample that makes still image on the LEDs.
In the main() function, the library operation is started by start() function and image data is set by set_data().
The image data is stored in 2 dimensional float array. 

#include "mbed.h"
#include "PCA9622_LED8x8.h"

PCA9622_LED8x8  matrix( p28, p27 );     //  I2C pins. SDA and SCL

int main()
{
    float   image[ 8 ][ 8 ];

    matrix.start();

    //  making 8x8 image to "image" array
    for ( int i = 0; i < 8; i++ )
        for ( int j = 0; j < 8; j++ )
            image[ i ][ j ]   = (i + 1) * (j + 1) / 64.0;

    //  set the image into library internal bufer
    matrix.set_data( image );

    while(1)
        ;
}


Physcal relation of the float image[8][8]

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image[5][0]image[5][1]image[5][2]image[5][3]image[5][4]image[5][5]image[5][6]image[5][7]
image[6][0]image[6][1]image[6][2]image[6][3]image[6][4]image[6][5]image[6][6]image[6][7]
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If you want to perform animation on the LEDs, it can be done by simple loop.
Keep the loop doing (1) store image data into the array and () call set_data() function.
The set_data() function can be called any time.

The set_data() function does copy the data in in-active side of internal buffer.
This library has two 8x8 buffers internally to perform "ping-pong" buffering. One side of the buffer is "active" and other side is "inactive".
The active side is the buffer for displaying data to LEDs. The inactive side is for user access.
The set_data() always access to the inactive side and after the inactive side filling is done, the active/inactive side switched at next scan start. 

    while(1)
    {
        //  do something for image array to store data;
        ....
        ...
        matrix.set_data( image );
        wait( 0.1 );
    }

Links

Components page
shop page (Japanese)
schematic
PCA9622

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