arduino and ws2803 led driver

Projects Programming
1

hi
I need to understand the following code on using 2 ws2803 led drivers with arduino

[quote]
[color=#7E7E7E]// WS2803_test[/color]
[color=#7E7E7E]// By Thomas Olson[/color]
[color=#7E7E7E]// teo20130202.01[/color]
[color=#7E7E7E]// WS2803 18 channel LED driver[/color]
[color=#7E7E7E]// Arduino 5V 16Mhz[/color]
[color=#7E7E7E]// WS2803 pin4 CKI - > ws2803_clockPin[/color]
[color=#7E7E7E]// WS2803 pin5 SDI - > ws2803_dataPin[/color]
[color=#7E7E7E]// WS2803 pin2 IREF = Rext to GND.[/color]
[color=#7E7E7E]// WS2803 pin6-23 = OUT0-17[/color]

[color=#7E7E7E]// According to the documentation...[/color]
[color=#7E7E7E]// WS2803 will receive 144 bits(18 bytes), latching it to itself[/color]
[color=#7E7E7E]// and then relay further bits to the next WS2803.[/color]
[color=#7E7E7E]//[/color]
[color=#7E7E7E]// But in fact, if you send more than 18 bytes say 36, then the[/color]
[color=#7E7E7E]// first 18 bytes are passed on to the second WS2803. And the next 18 bytes[/color]
[color=#7E7E7E]// are displayed in the first WS2803. And this is the behavior that is indicated[/color]
[color=#7E7E7E]// in timing chart (Fig 4.) of the documentation.[/color]
[color=#7E7E7E]//[/color]
[color=#7E7E7E]// This test code assumes two WS2803 in the chained together.[/color]
[color=#7E7E7E]// We will see that the second WS2803 displays the 1st-18th bytes sent and[/color]
[color=#7E7E7E]// the first WS2803 will display the 19th-36th bytes.[/color]
[color=#7E7E7E]// So...[/color]
[color=#7E7E7E]// The byte order is 0-17. The bit order is MSB-LSB. The chip order is Last to First.[/color]

[color=#CC6600]const[/color] [color=#CC6600]int[/color] ws2803_clockPin = 7;
[color=#CC6600]const[/color] [color=#CC6600]int[/color] ws2803_dataPin = 8;

#define nLEDs 36

uint8_t ledBar[nLEDs]; [color=#7E7E7E]// Array representing LED PWM levels (byte size)[/color]

[color=#CC6600]void[/color] [color=#CC6600][b]setup[/b][/color]() {
 
  [color=#CC6600]pinMode[/color](ws2803_clockPin, [color=#006699]OUTPUT[/color]);
  [color=#CC6600]pinMode[/color](ws2803_dataPin, [color=#006699]OUTPUT[/color]);

[color=#7E7E7E]// Initialize WS2803 - Clock needs to be low at least 600us to prepare itself.[/color]
  [color=#CC6600]digitalWrite[/color](ws2803_clockPin, [color=#006699]LOW[/color]);
  [color=#CC6600]delayMicroseconds[/color](600);

[color=#7E7E7E]// Initialize the ledBar array - all LEDs OFF.[/color]
  [color=#CC6600]for[/color]([color=#CC6600]int[/color] wsOut = 0; wsOut < nLEDs; wsOut++){
    ledBar[wsOut] = 0x00;
  }
  loadWS2803();
}

[color=#CC6600]void[/color] [color=#CC6600][b]loop[/b][/color]() {
  
[color=#7E7E7E]// Simple test - Flash All LEDs ON/OFF[/color]
  [color=#CC6600]for[/color]([color=#CC6600]int[/color] wsOut = 0;wsOut < nLEDs; wsOut++){
    ledBar[wsOut] = 0xFF; [color=#7E7E7E]// Full ON [/color]
  }
  loadWS2803();
[color=#7E7E7E]// Then turn them ALL off[/color]
  [color=#CC6600]for[/color]([color=#CC6600]int[/color] wsOut = 0; wsOut < nLEDs; wsOut++){
    ledBar[wsOut] = 0x00; [color=#7E7E7E]// Full OFF[/color]
  }
  loadWS2803();
  
  [color=#CC6600]delay[/color](1000);

[color=#7E7E7E]// Simple test - LED Chaser[/color]

  [color=#CC6600]for[/color]([color=#CC6600]int[/color] wsOut = 0; wsOut < nLEDs; wsOut++){
    ledBar[wsOut] = 0x3C; [color=#7E7E7E]// 23% brightness[/color]
    loadWS2803();

    [color=#CC6600]delay[/color](100);  [color=#7E7E7E]// ON time for each LED during chase.[/color]

    ledBar[wsOut] = 0x00; [color=#7E7E7E]// Full OFF[/color]
    loadWS2803();
  }

  [color=#CC6600]delay[/color](1000);

[color=#7E7E7E]/*  [/color]
[color=#7E7E7E]// Simple test - increase brightness to max and then dim to min each LED[/color]
[color=#7E7E7E]  for(int wsOut = 0; wsOut < nLEDs; wsOut++){[/color]
[color=#7E7E7E]    for(int iOut = 0; iOut < 256; iOut++){ // brighten one LED[/color]
[color=#7E7E7E]      ledBar[wsOut] = iOut;[/color]
[color=#7E7E7E]      loadWS2803();[/color]
[color=#7E7E7E]    }[/color]
[color=#7E7E7E]    for(int iOut = 0; iOut < 256; iOut++){ // now dim that one LED[/color]
[color=#7E7E7E]      ledBar[wsOut] = (uint8_t)0xFF & 255-iOut;[/color]
[color=#7E7E7E]      loadWS2803();[/color]
[color=#7E7E7E]    }[/color]
[color=#7E7E7E]  }[/color]

[color=#7E7E7E]  delay(1000);[/color]
[color=#7E7E7E]*/[/color]

} [color=#7E7E7E]//loop[/color]

[color=#CC6600]void[/color] loadWS2803(){
    [color=#CC6600]for[/color] ([color=#CC6600]int[/color] wsOut = 0; wsOut < nLEDs; wsOut++){
    [color=#CC6600]shiftOut[/color](ws2803_dataPin, ws2803_clockPin, [color=#006699]MSBFIRST[/color], ledBar[wsOut]);
    }
    [color=#CC6600]delayMicroseconds[/color](600); [color=#7E7E7E]// 600us needed to reset WS2803s[/color]
}

[/quote]

I ain't a noob in coding but I need help with the for statements and hexadecimal thingys

2

Can you please copy/paste your code from the IDE straight into code tags to avoid all the color crap ?

3

// WS2803_test
// By Thomas Olson
// teo20130202.01
// WS2803 18 channel LED driver
// Arduino 5V 16Mhz
// WS2803 pin4 CKI - > ws2803_clockPin
// WS2803 pin5 SDI - > ws2803_dataPin
// WS2803 pin2 IREF = Rext to GND.
// WS2803 pin6-23 = OUT0-17

// According to the documentation...
// WS2803 will receive 144 bits(18 bytes), latching it to itself
// and then relay further bits to the next WS2803.
//
// But in fact, if you send more than 18 bytes say 36, then the
// first 18 bytes are passed on to the second WS2803. And the next 18 bytes
// are displayed in the first WS2803. And this is the behavior that is indicated
// in timing chart (Fig 4.) of the documentation.
//
// This test code assumes two WS2803 in the chained together.
// We will see that the second WS2803 displays the 1st-18th bytes sent and
// the first WS2803 will display the 19th-36th bytes.
// So...
// The byte order is 0-17. The bit order is MSB-LSB. The chip order is Last to First.

const int ws2803_clockPin = 7;
const int ws2803_dataPin = 8;

#define nLEDs 36

uint8_t ledBar[nLEDs]; // Array representing LED PWM levels (byte size)

void setup() {

pinMode(ws2803_clockPin, OUTPUT);
pinMode(ws2803_dataPin, OUTPUT);

// Initialize WS2803 - Clock needs to be low at least 600us to prepare itself.
digitalWrite(ws2803_clockPin, LOW);
delayMicroseconds(600);

// Initialize the ledBar array - all LEDs OFF.
for(int wsOut = 0; wsOut < nLEDs; wsOut++){
ledBar[wsOut] = 0x00;
}
loadWS2803();
}

void loop() {

// Simple test - Flash All LEDs ON/OFF
for(int wsOut = 0;wsOut < nLEDs; wsOut++){
ledBar[wsOut] = 0xFF; // Full ON
}
loadWS2803();
// Then turn them ALL off
for(int wsOut = 0; wsOut < nLEDs; wsOut++){
ledBar[wsOut] = 0x00; // Full OFF
}
loadWS2803();

delay(1000);

// Simple test - LED Chaser

for(int wsOut = 0; wsOut < nLEDs; wsOut++){
ledBar[wsOut] = 0x3C; // 23% brightness
loadWS2803();

delay(100); // ON time for each LED during chase.

ledBar[wsOut] = 0x00; // Full OFF
loadWS2803();
}

delay(1000);

/*
// Simple test - increase brightness to max and then dim to min each LED
for(int wsOut = 0; wsOut < nLEDs; wsOut++){
for(int iOut = 0; iOut < 256; iOut++){ // brighten one LED
ledBar[wsOut] = iOut;
loadWS2803();
}
for(int iOut = 0; iOut < 256; iOut++){ // now dim that one LED
ledBar[wsOut] = (uint8_t)0xFF & 255-iOut;
loadWS2803();
}
}

delay(1000);
*/

} //loop

void loadWS2803(){
for (int wsOut = 0; wsOut < nLEDs; wsOut++){
shiftOut(ws2803_dataPin, ws2803_clockPin, MSBFIRST, ledBar[wsOut]);
}
delayMicroseconds(600); // 600us needed to reset WS2803s
}