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Showing use of Maxim LED Driver with DOT matric LCD Modules
Shows the use of the Maxim 7219 with the MBED. Based on some Arduino code (must find the original link)
Diff: main.cpp
- Revision:
- 0:0b95cf14c97b
- Child:
- 1:ba7a97159510
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/main.cpp Thu Jan 22 12:19:23 2015 +0000 @@ -0,0 +1,104 @@ +#include "mbed.h" +/* +example of driving maxim chip for Glasgow Uni Projects. + +Dr J.J.Trinder 2013,14 +jon.trinder@glasgow.ac.uk + + +*/ + +#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 + +SPI max72_spi(PTD2, NC, PTD1); +DigitalOut load(PTD0); //will provide the load signal + + +char pattern_diagonal[8] = { 0x01, 0x2,0x4,0x08,0x10,0x20,0x40,0x80}; +char pattern_square[8] = { 0xff, 0x81,0x81,0x81,0x81,0x81,0x81,0xff}; +char pattern_star[8] = { 0x04, 0x15, 0x0e, 0x1f, 0x0e, 0x15, 0x04, 0x00}; + + +/* +Write to the maxim via SPI +args register and the column data +*/ +void write_to_max( int reg, int col) +{ + load = LOW; // begin + max72_spi.write(reg); // specify register + max72_spi.write(col); // put data + load = HIGH; // make sure data is loaded (on rising edge of LOAD/CS) +} + +//writes 8 bytes to the display +void pattern_to_display(char *testdata){ + int cdata; + for(int idx = 0; idx <= 7; idx++) { + cdata = testdata[idx]; + write_to_max(idx+1,cdata); + } +} + + +void setup_dot_matrix () +{ + // initiation of the max 7219 + // SPI setup: 8 bits, mode 0 + max72_spi.format(8, 0); + + + + max72_spi.frequency(100000); //down to 100khx easier to scope ;-) + + + write_to_max(max7219_reg_scanLimit, 0x07); + write_to_max(max7219_reg_decodeMode, 0x00); // using an led matrix (not digits) + write_to_max(max7219_reg_shutdown, 0x01); // not in shutdown mode + write_to_max(max7219_reg_displayTest, 0x00); // no display test + for (int e=1; e<=8; e++) { // empty registers, turn all LEDs off + write_to_max(e,0); + } + // maxAll(max7219_reg_intensity, 0x0f & 0x0f); // the first 0x0f is the value you can set + write_to_max(max7219_reg_intensity, 0x08); // try of lowering psu pull jan 15 jt + +} + +void clear(){ + for (int e=1; e<=8; e++) { // empty registers, turn all LEDs off + write_to_max(e,0); + } +} + + +int main() +{ + setup_dot_matrix (); /* setup matric */ + while(1){ + //da_star(); + pattern_to_display(pattern_diagonal); + wait_ms(1000); + pattern_to_display(pattern_square); + wait_ms(1000); + pattern_to_display(pattern_star); + wait_ms(1000); + clear(); + + } +} \ No newline at end of file