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A generic library to support Max7221 chip for 8 digit 7 segment displays
MAXIM SPI interfaced, 8 digit LED display Driver
MAX221
- The image below was my initial development setup. The top of the image shows a wire wrap connection to a Max7221 to an 8 digit 7 segment display.
- The small board below it is the new max7221 board that was created with surface mount chips and using a toaster oven to do reflow soldering.
Example of using a single Max7221 on SPI p5,p6,p7
Import program
00001 #include "mbed.h" 00002 #include "Max7221.h" 00003 00004 00005 // p5: DIN, p7: CLK, p8: LOAD/CS 00006 Max7221 max7221disp1(p5, p7, p8); 00007 //Max7221 max7221disp2(p5, p7, p8); 00008 //Max7221 max7221disp3(p11, p13, p14); 00009 //Max7221 max7221disp4(p11, p13, p14); 00010 00011 int count=-99; 00012 00013 void loop(void) { 00014 max7221disp1=count; 00015 if (count < 100) 00016 count=count+1; 00017 else 00018 count=-99; 00019 } 00020 00021 int main() { 00022 max7221disp1.Setup(); 00023 //Max7221::SetupALl(); 00024 max7221disp1.WriteFloat(123.125); 00025 wait(1.0); 00026 00027 while (1) { 00028 loop(); 00029 wait(1.0); 00030 } 00031 } 00032 00033
Diff: MAX7221/Max7221.h
- Revision:
- 1:d8589d1f368c
- Child:
- 2:828c62cc1861
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MAX7221/Max7221.h Tue Aug 06 08:18:53 2013 +0000 @@ -0,0 +1,68 @@ +#ifndef Max7221_H +#define Max7221_H + +// define max7219/max7221 registers +#define max7219_reg_noop 0x00 +#define max7219_reg_digit0 0x01 +#define max7219_reg_digit1 0x02 +#define max7219_reg_digit2 0x03 +#define max7219_reg_digit3 0x04 +#define max7219_reg_digit4 0x05 +#define max7219_reg_digit5 0x06 +#define max7219_reg_digit6 0x07 +#define max7219_reg_digit7 0x08 +#define max7219_reg_decodeMode 0x09 +#define max7219_reg_intensity 0x0a +#define max7219_reg_scanLimit 0x0b +#define max7219_reg_shutdown 0x0c +#define max7219_reg_displayTest 0x0f + +#define LOW 0 +#define HIGH 1 +#define MHZ 1000000 +#define NUMDIGITS 8 + +#ifdef NUMDIGITS +#define UPPERBOUND 99999999 +#define LOWERBOUND -9999999 +#endif + +class Max7221 { +public: + Max7221(PinName msoi=p5, PinName mclk=p7, PinName load=p8); + + void Write( unsigned int reg, unsigned int col); + + void WriteInt( int value ); + void WriteFloat( float value); + Max7221& operator= (int value){ + WriteInt(value); + return *this; + }; + Max7221& operator= (float value){ + WriteFloat(value); + return *this; + }; + + void Setup (void); + + static void WriteAll (unsigned int reg, unsigned int col); + static void SetupAll (void); + +private: + SPI *max72_spi; + DigitalOut *load; + int id; + int *maxInUse; + + + static SPI *spi1; + static SPI *spi2; + static DigitalOut *load1; + static DigitalOut *load2; + static int maxInUseSPI1; + static int maxInUseSPI2; + +}; + +#endif \ No newline at end of file