| Testing the MAX7221 - 24 Hour Countdown Sketch |  |
| Think 7-Segment, LED Displays and you cannot help but think of the standard displays of heinous bombs in action films or that frantic TV series 24. I could think of nothing more fitting to test my new display than a countdown timer! Here is the code and a short video of said timer in action. Hopefully the commenting in the code is sufficient to explain it’s function, if you have any questions please leave them in the comments… // ******************************************************************** // * 24 Hour Coundown * // * Because if you have just built a MAX7221/MAX7219 Based 8 Digit, * // * 7 Segment, LED Display then you will want to test it somehow. * // * Nothing says LED Segment display more than a TV/Film style * // * countdown timer. * // * * // * A silly test routine by Blair Thompson - www.justblair.co.uk * // ******************************************************************** #include <LedControl.h> //We cant do anything without importing a suitable library! // Lets start with the pinouts to the Max72xx led driver // ***************************************************** int DIN = 12; // Pin 1 on the Max72xx int CLK = 11; // Pin 13 on the Max72xx int LOADCS = 10; // Pin 12 on the Max72xx int flashDelay = 100; // delay in MS (100=1/10th second) int ledBrightness = 15; // range is 0-15. 0=lowest, 15 = full power // define the LedControl instance - if I want more I can setup lc2, lc3 etc // ************************************************************************ LedControl lc=LedControl(DIN,CLK,LOADCS,1); // DIN, CLK, Load/CS, 1 = only one chip MAX chip attached. void setup() { pinMode(DIN, OUTPUT); // once only, lets make the pins outputs pinMode(CLK, OUTPUT); pinMode(LOADCS, OUTPUT); // take pins out of power save mode. No updates otherwise. for(int index=0;index<lc.getDeviceCount();index++) { lc.shutdown(index,false); } lc.setIntensity(0,ledBrightness ); //set the brightness } void loop() // here comes the good stuff, the main loop! { int row = 0; //Set the starting position int chipId = 0; //This is not strictly reqd, but if using more than one display this will be needed // First lets display the hours // **************************** for (int hourcountdown=24; hourcountdown>0; hourcountdown--){ int x=hourcountdown; int hourones; int hourtens; hourones=x%10; hourtens=x/10%10; // %10 divides by ten and extracts the remainder lc.setChar(chipId, row+5, 'h', false); // Adds the letter H lc.setDigit(chipId, row+6, (byte) hourones, false); // These two lines add the numerical hours lc.setDigit(chipId, row+7, (byte) hourtens, false); // This technique is repeated several times! // Now the minutes for (int minutecountdown=60; minutecountdown >0; minutecountdown--){ int y=minutecountdown; int minuteones; int minutetens; minuteones=y%10; minutetens=y/10%10; // %10 divides by ten and extracts the remainder lc.setDigit(chipId, row+3, minuteones, true); // These two lines add the numerical hours lc.setDigit(chipId, row+4, minutetens, false); // Deja Vu? // And the seconds/tenths just to make it look exciting! for (int seccountdown=600; seccountdown>0; seccountdown--){ int v=seccountdown; int tenths; int secones; int sectens; int thousands; tenths=v%10; // Again divide by 10 and calculate the remainder secones=v/10%10; sectens=v/100%10; thousands=v/1000%10; lc.setDigit(chipId, row, (byte) tenths, false); lc.setDigit(chipId, row+1, (byte) secones, true); // True in the arguments activates the dot... lc.setDigit(chipId, row+2, (byte) sectens, false); delay (flashDelay); } } } } // *** That's All Folks!!! Jack Bauer eat your heart out! *** Click the image below to see it in action... Apologies, Spielburg I am not! Dim lights Embed Embed this video on your site
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