PCA9622_LED8x8.h

00001 /**
00002  *  PCA9622 LED 8x8 library
00003  *
00004  *  @author  Tedd OKANO
00005  *  @version 1.1.1
00006  *  @date    26-Feb-2015
00007  *
00008  *  Library for "I2C 8x8 LED matrix board" from Switch Science
00009  *    https://www.switch-science.com/catalog/2071/
00010  *
00011  *  The I2C LED controller PCA9622 is used on this module
00012  *  This LED controller chip enables brightness control by PWM.
00013  *
00014  *  For more information about the PCA9622:
00015  *    http://www.nxp.com/documents/data_sheet/PCA9622.pdf
00016  */
00017 
00018 #ifndef MBED_PCA9622_LED8x8_H
00019 #define MBED_PCA9622_LED8x8_H
00020 
00021 #include "mbed.h"
00022 
00023 /** PCA9622_LED8x8 class
00024  *
00025  *  PCA9622_LED8x8: A library to control LED matrix using the PCA9622
00026  *
00027  *  PCA9622 is an I2C LED controller.
00028  *  This library operates LED 8x8 matrix through the PCA9622.
00029  *
00030  *  Example:
00031  *  @code
00032  *  #include "mbed.h"
00033  *  #include "PCA9622_LED8x8.h"
00034  *
00035  *  PCA9622_LED8x8  matrix( p28, p27 );     //  for 40pin type mbed
00036  *  //PCA9622_LED8x8  matrix( D14, D15 );   //  for Arduino type mbed
00037  *  //PCA9622_LED8x8  matrix( dp5, dp27 );  //  for mbed LPC1114
00038  *
00039  *  float func( float x, float y, float t );    //  function to make 8x8 image
00040  *
00041  *  int main()
00042  *  {
00043  *      float   image[ 8 ][ 8 ];  //
00044  *      int     count   = 0;
00045  *
00046  *      matrix.start();
00047  *
00048  *      while(1) {
00049  *
00050  *          //  making 8x8 image to "image" array
00051  *          for ( int i = 0; i < 8; i++ )
00052  *              for ( int j = 0; j < 8; j++ )
00053  *                  image[ i ][ j ]   = func( i, j, count * 0.2 );
00054  *
00055  *          matrix.set_data( image );
00056  *
00057  *          count++;
00058  *          wait( 0.05 );
00059  *      }
00060  *  }
00061  *
00062  *  float func( float x, float y, float t )
00063  *  {
00064  *  //#define     DISPLAY_OFFSET  3.5
00065  *  #define     DISPLAY_OFFSET  0
00066  *  #define     SIZE            0.3
00067  *
00068  *      float   s;
00069  *
00070  *      x   = (x - DISPLAY_OFFSET) * SIZE;
00071  *      y   = (y - DISPLAY_OFFSET) * SIZE;
00072  *
00073  *      s   = cos( powf( x * x + y * y, 0.5 ) - t );
00074  *      return ( powf( s, 4.0 ) );
00075  *  }
00076  *  @endcode
00077  */
00078 
00079 class PCA9622_LED8x8
00080 {
00081 public:
00082     enum FrameRate { DEFAULT_FRAMERATE   = 50 };
00083 
00084     /** Create a PCA9622_LED8x8 instance for the LED matrix board
00085      *  which is connected to specified I2C pins with specified address
00086      *
00087      * @param sda I2C-bus SDA pin
00088      * @param scl I2C-bus SCL pin
00089      * @param slave_adr (option) I2C-bus address (default: 0xA0)
00090      * @param fr (option) frame rate (in "Hz". default: 100)
00091      */
00092     PCA9622_LED8x8( PinName sda, PinName scl, char slave_adr = 0xA0, float fr = DEFAULT_FRAMERATE );
00093 
00094     /** Create a PCA9622_LED8x8 instance for the LED matrix board
00095      *  which is connected to specified I2C pins with specified address
00096      *
00097      * @param i2c_obj I2C object (instance)
00098      * @param slave_adr (option) I2C-bus address (default: 0xA0)
00099      * @param fr (option) frame rate (in "Hz". default: 100)
00100      */
00101     PCA9622_LED8x8( I2C &i2c_obj, char slave_adr = 0xA0, float fr = DEFAULT_FRAMERATE );
00102 
00103     /** Destructor of PCA9622_LED8x8
00104      */
00105     ~PCA9622_LED8x8();
00106 
00107     /** Frame rate change
00108      *
00109      *  Changes frame rate (scan rate of the matrix)
00110      *
00111      * @param rate Frame rate in "Hz"
00112      */
00113     void    frame_rate( float rate );
00114 
00115     /** Start operation
00116      *
00117      *  The LED matrix operation need to be started with this function.
00118      *  Scan line drawing by Ticker interrupt will be started.
00119      */
00120     void    start( void );
00121 
00122     /** Stop operation
00123      *
00124      *  This stops the operation.
00125      *  Ticker interrupt will be stopped
00126      */
00127     void    stop( void );
00128 
00129     /** Set the image to library internal buffer
00130      *
00131      *  8x8 pixel image will be copied into the library internal buffer.
00132      *  User don't need to care the timing of this function call because
00133      *  the library is using "ping-pong" buffering.
00134      *  This function writes data into in-active side of the buffer.
00135      *  The image will not be appear immediatly but from next scan start.
00136      *
00137      *  Each elements of the array should be brightness information
00138      *  in range of 0.0 to 1.0.
00139      *
00140      *  The 2 dimensional 8x8 array will be handled as..
00141      *
00142      *  p[0][0] : top-left
00143      *  p[0][7] : top-right
00144      *  p[7][0] : bottm-left
00145      *  p[7][7] : bottom-right
00146      *
00147      *  @param p image stored 2-dimensional float array
00148      */
00149     void    set_data( float p[ 8 ][ 8 ] );
00150 
00151 private:
00152     I2C     *i2c_p;
00153     I2C     &i2c;
00154     char    address;                //  I2C slave address
00155     float   framerate;              //  frame rate in "Hz"
00156     int     in_operation;           //  ture, if scan is on-going
00157     int     line_counter;           //  counting scan line
00158     int     frame_counter;          //  counting frame number
00159     int     buffer_switch_request;  //  flag to switch the ping-pong buffer
00160     int     outgoing_buffer;        //  flag to select the buffer
00161     Ticker  t;
00162     char    pattern[ 2 ][ 8 ][ 8 ]; //  having 2 sets of 8x8 array for pin-pong buffering
00163 
00164     void    draw_a_line( void );    //  ISR called by Ticker
00165     void    initialize( void );     //  initialize function
00166 };
00167 
00168 #endif  //  MBED_PCA9622_LED8x8_H