main.cpp

00001 #include "mbed.h"
00002 
00003 // PC_3: DIN, PB_10: CLK, D2: LOAD/CS
00004 SPI max72_spi(PC_3, NC, PB_10);
00005 DigitalOut load(D2);
00006 
00007 int maxInUse = 1;    //change this variable to set how many MAX7219's you'll use
00008 
00009 // define max7219 registers
00010 #define max7219_reg_noop         0x00
00011 #define max7219_reg_digit0       0x01
00012 #define max7219_reg_digit1       0x02
00013 #define max7219_reg_digit2       0x03
00014 #define max7219_reg_digit3       0x04
00015 #define max7219_reg_digit4       0x05
00016 #define max7219_reg_digit5       0x06
00017 #define max7219_reg_digit6       0x07
00018 #define max7219_reg_digit7       0x08
00019 #define max7219_reg_decodeMode   0x09
00020 #define max7219_reg_intensity    0x0a
00021 #define max7219_reg_scanLimit    0x0b
00022 #define max7219_reg_shutdown     0x0c
00023 #define max7219_reg_displayTest  0x0f
00024 
00025 #define LOW 0
00026 #define HIGH 1
00027 #define MHZ 1000000
00028 
00029 void maxSingle( int reg, int col) {
00030 //maxSingle is the "easy"  function to use for a
00031 //single max7219
00032     load = LOW;            // begin
00033     max72_spi.write(reg);  // specify register
00034     max72_spi.write(col);  // put data
00035     load = HIGH;           // make sure data is loaded (on rising edge of LOAD/CS)
00036 }
00037 
00038 void maxAll (int reg, int col) {    // initialize  all  MAX7219's in the system
00039     load = LOW;                    // begin
00040     for ( int c=1; c<= maxInUse; c++) {
00041         max72_spi.write(reg);  // specify register
00042         max72_spi.write(col);  // put data
00043     }
00044     load = HIGH;
00045 }
00046 
00047 void maxOne(int maxNr, int reg, int col) {
00048 //maxOne is for adressing different MAX7219's,
00049 //while having a couple of them cascaded
00050     int c = 0;
00051     load = LOW;
00052 
00053     for ( c = maxInUse; c > maxNr; c--) {
00054         max72_spi.write(0);  // no-op
00055         max72_spi.write(0);  // no-op
00056     }
00057 
00058     max72_spi.write(reg);  // specify register
00059     max72_spi.write(col);  // put data
00060 
00061     for ( c=maxNr-1; c >= 1; c--) {
00062         max72_spi.write(0);  // no-op
00063         max72_spi.write(0);  // no-op
00064     }
00065     load = HIGH;
00066 }
00067 
00068 
00069 void setup () {
00070     // initiation of the max 7219
00071     // SPI setup: 8 bits, mode 0
00072     max72_spi.format(8, 0);
00073     
00074     // going by the datasheet, min clk is 100ns so theoretically 10MHz should work...
00075     // max72_spi.frequency(10*MHZ);
00076     
00077     maxAll(max7219_reg_scanLimit, 0x07);
00078     maxAll(max7219_reg_decodeMode, 0x00);  // using an led matrix (not digits)
00079     maxAll(max7219_reg_shutdown, 0x01);    // not in shutdown mode
00080     maxAll(max7219_reg_displayTest, 0x00); // no display test
00081     for (int e=1; e<=8; e++) {    // empty registers, turn all LEDs off
00082         maxAll(e,0);
00083     }
00084     maxAll(max7219_reg_intensity, 0x0f & 0x0f);    // the first 0x0f is the value you can set
00085     // range: 0x00 to 0x0f
00086 }
00087 
00088 
00089 /*   maxSingle(1,1);                       //  - - - - - - - +      
00090      maxSingle(2,2);                       //  - - - - - - + -
00091      maxSingle(3,4);                       //  - - - - - + - -
00092      maxSingle(4,8);                       //  - - - - + - - -
00093      maxSingle(5,16);                      //  - - - + - - - -
00094      maxSingle(6,32);                      //  - - + - - - - -
00095      maxSingle(7,64);                      //  - + - - - - - -
00096      maxSingle(8,128);                     //  + - - - - - - -
00097      wait_ms(2000);
00098      */
00099 int main() {
00100     setup ();
00101     while(1){
00102             for(int i=1;i<=8;i++){
00103             for(int j=1;j<=128;j*=2){
00104             maxSingle(i,j);
00105             wait(0.1);
00106             }
00107             }
00108             for(int i=8;i>=1;i--){
00109             for(int j=128;j>=1;j*=0.5){
00110             maxSingle(i,j);
00111             wait(0.1);
00112             }
00113             }
00114     }
00115 }