Dwayne Dilbeck
/
Max7221
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.h
- Revision:
- 3:5abc4047af8d
- Parent:
- 2:828c62cc1861
- Child:
- 4:e2b160410338
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Max7221.h Wed Aug 07 02:34:59 2013 +0000 @@ -0,0 +1,179 @@ +/** +* @file Max7221.h +* @brief This file contains the class defnition of Max7221 and define statements related to the class, and max7221 device +* The methods in this class are derived from posts on the mbed forum written by Igor Skochinsky on October 2009 +* +* @author Dwayne S. Dilbeck +* +* @date 8/6/2013 +*/ +#ifndef Max7221_H +#define Max7221_H + +/** Max7221 Example + * @code + * #include "mbed.h" + * #include "Max7221.h" + * + * + * // p5: DIN, p7: CLK, p8: LOAD/CS + * Max7221 max7221disp1(p5, p7, p8); + * //Max7221 max7221disp2(p5, p7, p8); + * //Max7221 max7221disp3(p11, p13, p14); + * //Max7221 max7221disp4(p11, p13, p14); + * + * int count=-99; + * + * void loop(void) { + * max7221disp1.WriteInt(count); + * if (count < 100) + * count=count+1; + * else + * count=-99; + * } + * + * int main() { + * max7221disp1.Setup(); + * //Max7221::SetupALl(); + * max7221disp1.WriteFloat(123.125); + * wait(1.0); + * + * while (1) { + * loop(); + * wait(1.0); + * } + * } + * @endcode + */ + +// 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: +/** +* Constructor. This is the default constructor +* @author Dwayne S. Dilbeck +* @param msoi The SPI pin used as input to the device. Valid values for LPC1768 are p5 or p11 +* @param mclk The SPI pin used as clock for the device. Valid values for LPC1768 are p7 or p13 +* @param load The pin used to control load for the device. Any pin capable for DigitalOut can be used, but the same load pin must be used for +* device that share the same msoi and mclk pins +* @date 8/6/2013 +*/ + Max7221(PinName msoi=p5, PinName mclk=p7, PinName load=p8); + +/** +* This method is used to write a byte of data to a specified register for only the device defined in this class instance +* @author Dwayne S. Dilbeck +* @param reg The register to write to. +* @param data The value to be written. +* @date 8/6/2013 +*/ + void Write( unsigned int reg, unsigned int data); + +/** +* This method is used to display an integer to the specified device instance. Underflow and overflow result in '-' written to all digits +* @author Dwayne S. Dilbeck +* @param value An integer value to display +* @date 8/6/2013 +*/ + void WriteInt( int value ); + +/** +* This method is used to display a floating point number to the specified device instance. +* Underflow and overflow result in '-' written to all digits. The digits after the decimal +* point are truncated to fit the display. +* @author Dwayne S. Dilbeck +* @param value A float value to display +* @date 8/6/2013 +*/ + void WriteFloat( float value); + +/** +* Overload of the EQUALS operator to provide easy use of the class. +* @author Dwayne S. Dilbeck +* @param value An integer value to display +* @date 8/6/2013 +*/ + + Max7221& operator= (int value){ + WriteInt(value); + return *this; + }; +/** +* Overload of the EQUALS operator to provide easy use of the class. +* @author Dwayne S. Dilbeck +* @param value A float value to display +* @date 8/6/2013 +*/ + + Max7221& operator= (float value){ + WriteFloat(value); + return *this; + }; +/** +* This method is used to write an intial set off values to the device to prepare it for use. +* @author Dwayne S. Dilbeck +* @date 8/6/2013 +*/ + void Setup (void); + +/** +* This method is used to write a byte of data to a specified register for all the devices instantiated. +* @author Dwayne S. Dilbeck +* @param reg The register to write to. +* @param data The value to be written. +* @date 8/6/2013 +*/ + static void WriteAll (unsigned int reg, unsigned int data); + +/** +* This method is used to write an intial set off values to ALL device to prepare them for use. +* @author Dwayne S. Dilbeck +* @date 8/6/2013 +*/ + static void SetupAll (void); + +private: + /// Pointer for the class instance to a particular SPI bus + SPI *max72_spi; + /// pointer for the class instance of a particular load signal + DigitalOut *load; + /// id of the class instance + int id; + /// pointer to the number of devices connected to the SPI bus instance this device instance is connected to. + int *maxInUse; + + ///For the class we have a static set of values. There are 2 SPI buses, 2 load signals, and 2 counters of the number of devices connected to a SPI bus. + 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