Max7221.h

00001 /**
00002 * @file Max7221.h
00003 * @brief Header file for the MAX7219/7221 driver class.
00004 * 
00005 * @author Grzegorz Kaczmarek
00006 * @comment Code inspired on earlier Dwayne S. Dilbeck's work
00007 * @date 20/11/2015
00008 */
00009 
00010 #ifndef Max7221_H
00011 #define Max7221_H
00012 
00013 // MAX7219/7221 register map
00014 #define max7221_reg_noop         0x00
00015 #define max7221_reg_digit0       0x01
00016 #define max7221_reg_digit1       0x02
00017 #define max7221_reg_digit2       0x03
00018 #define max7221_reg_digit3       0x04
00019 #define max7221_reg_digit4       0x05
00020 #define max7221_reg_digit5       0x06
00021 #define max7221_reg_digit6       0x07
00022 #define max7221_reg_digit7       0x08
00023 #define max7221_reg_decodeMode   0x09
00024 #define max7221_reg_intensity    0x0A
00025 #define max7221_reg_scanLimit    0x0B
00026 #define max7221_reg_shutdown     0x0C
00027 #define max7221_reg_displayTest  0x0F
00028 
00029 // Logical values
00030 #define LOG_0 0
00031 #define LOG_1 1
00032 
00033 class Max7221 {
00034 private:
00035     static SPI *mp_spi;             // SPI used for this display (no data transmission when NULL)
00036     static DigitalOut *mp_cs;       // /CS signal (it should be handled manually when NULL)
00037     static unsigned int m_counter;  // Total number of displays on SPI chain
00038     unsigned int m_position;        // Display position on SPI chain (0 = 1'st)
00039 public:
00040     /**
00041     *  Default constructor.
00042     *  At least one instance should set SPI and /CS pointers for display chain to work.
00043     *  Use SetSpi() and SetCs() or parametrized constructor.
00044     */
00045     Max7221();
00046 
00047     /**
00048     *  Constructor.
00049     *  Sets SPI and /CS pointers. Display chain is operational.
00050     */
00051     Max7221(SPI *spi, DigitalOut *cs);
00052 
00053     /**
00054     *  Sets pointer to configured SPI.
00055     *  SPI is used by all display instances.
00056     */
00057     void SetSpi(SPI *spi);
00058 
00059     /**
00060     *  Sets pointer to configured /CS signal.
00061     *  /CS signal is used by all display instances.
00062     */    
00063     void SetCs(DigitalOut *cs);
00064 
00065     /**
00066     *  Method for setting /CS signal LOW (enable data reception).
00067     */
00068     void CsLow(void);
00069 
00070     /**
00071     *  Method for setting /CS signal HIGH (received data is latched and processed).
00072     */
00073     void CsHigh(void);
00074 
00075     /**
00076     *  Method used to send data over SPI (no use of /CS signal).
00077     *  To be used with display chains and when building display libraries
00078     *  where amount of data needs to be pushed via SPI in one transaction.
00079     */
00080     void WriteRaw(unsigned int reg, unsigned int data);
00081    
00082     /**
00083     *  Method for sending register-value pair for this diasplay.
00084     *  Supports display chain on single SPI (m_position > 0).
00085     */
00086     void Write(unsigned int reg, unsigned int data);
00087 
00088     /**
00089     *  Sets test mode which causes all display LEDs to emit light with full brightess.
00090     *  @param mode  true - test mode, false - normal operation.
00091     */
00092     void TestMode(bool mode);
00093     
00094     /**
00095     *  Sets amount of digits to be used by this display.
00096     *  @param digits_no  1 - one digit, (2-7), 8 - all 8 digits.
00097     */
00098     void UseDigitsNo(unsigned int digits_no);
00099 
00100     /**
00101     *  Selects for which digits Code-B data decoding is used.
00102     *  @param mode  0x00 - no decoding, 0x0F - digits 0-3, 0xFF - all digits.
00103     */
00104     void DecodeMode(unsigned int mode);
00105 
00106     /**
00107     *  Sends data to selected digit.
00108     *  @param digit_no  Selected digit (0-7).
00109     *  @param digit_no  Data to display.
00110     */
00111     void WriteDigit(unsigned int digit_no, unsigned int value);
00112 
00113     /**
00114     *  Sets display brightness.
00115     *  @param intensity  0x00 - minimum brightness, 0x0F - maximum brightness.
00116     */
00117     void Intensity(unsigned int intensity);
00118 
00119     /**
00120     *  Sets display operation mode.
00121     *  @param mode  true - normal operation, false - shutdown mode.
00122     */
00123     void OperationMode(bool mode);
00124     
00125     /**
00126     *  Initial setup of this display.
00127     *  8-digit blank decimal display set to nimimal brightness.
00128     *  Supports display chain on single SPI (m_position > 0).
00129     */   
00130     void Setup(void);
00131 };
00132 
00133 #endif