I have a 300 LED WS2812B strip connected to a MEGA 2560 via pin 22 and ground. I am powering the LED strip with 5V from an ATX PSU. I am using Jinx to control the strip.
Doing a basic color test red, blue, and green all map out properly and look fine. Mixing colors with the green and blue look fine. Perfectly consistent. Mix anything with red and it starts red by the Mega and slowly fades to the proper mix color by the end of the strip.
I don't now if it makes any difference, but the PSU is connected at the far end of the strip where the colors are mixing properly with red and any other channel. They fade back perfectly evenly to the Mega with only a little mixed at the closest LED.
Jinx is configured to use Glediator as an output. The code on the Mega is
//##############################################################################
//##############################################################################
// #
// Glediator to WS2812 pixel converter #
// by R. Heller #
// V 1.0 - 07.01.2014 #
// wwww.SolderLab.de #
// #
// Receives serial data in Glediator protocol format @ 1 MBit/s #
// and distributes it to a connectect chain of WS2812 pixels #
// #
// Adjust the correct DATA PIN and the correct NUMBER OF PIXELS you are using #
// in the definitions section below before uploading this sketch to your #
// Arduino device. #
// #
// Maxiumim number of supported pixeles is 512 !!! #
// #
// In the Glediator software set output mode to "Glediator_Protocol", #
// color order to "GRB" and baud rate to "1000000" #
// #
//##############################################################################
//##############################################################################
//##############################################################################
// #
// Definitions --> Make changes ONLY HERE #
// #
// To find out the correct port, ddr and pin name when you just know the #
// Arduino's digital pin number just google for "Arduino pin mapping". #
// In the present example digital Pin 6 is used which corresponds to "PORTD", #
// "DDRD" and "6", respectively. #
// #
//##############################################################################
#define DATA_PORT PORTA
#define DATA_DDR DDRA
#define DATA_PIN 0 //This relates to PDA0 (PIN 22 on the Mega 2560)
#define NUMBER_OF_PIXELS 300
//##############################################################################
// #
// Variables #
// #
//##############################################################################
unsigned char display_buffer[NUMBER_OF_PIXELS * 3];
static unsigned char *ptr;
static unsigned int pos = 0;
boolean go = 0;
//##############################################################################
// #
// Setup #
// #
//##############################################################################
void setup()
{
// Set data pin as output
DATA_DDR |= (1<<DATA_PIN);
// Initialize UART
UCSR0A |= (1<<U2X0);
UCSR0B |= (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0);
UCSR0C |= (1<<UCSZ01) | (1<<UCSZ00) ;
UBRR0H = 0;
UBRR0L = 1; //Baud Rate 1 MBit (at F_CPU = 16MHz)
ptr=display_buffer;
//Enable global interrupts
sei();
}
//##############################################################################
// #
// Main loop #
// #
//##############################################################################
void loop()
{
if (go==1)
{
cli();
ws2812_sendarray(display_buffer, NUMBER_OF_PIXELS * 3);
sei();
go=0;
}
}
//##############################################################################
// #
// UART-Interrupt-Prozedur (called every time one byte is compeltely received) #
// #
//##############################################################################
ISR(USART0_RX_vect)
{
unsigned char b;
b=UDR0;
if (b == 1) {pos=0; ptr=display_buffer; return;}
if (pos == (NUMBER_OF_PIXELS*3)) {} else {*ptr=b; ptr++; pos++;}
if (pos == ((NUMBER_OF_PIXELS*3)-1)) {go=1;}
}
//##############################################################################
// #
// WS2812 output routine #
// Extracted from a ligh weight WS2812 lib by Tim (cpldcpu@gmail.com) #
// Found on wwww.microcontroller.net #
// Requires F_CPU = 16MHz #
// #
//##############################################################################
void ws2812_sendarray(uint8_t *data,uint16_t datlen)
{
uint8_t curbyte,ctr,masklo;
uint8_t maskhi = _BV(DATA_PIN);
masklo =~ maskhi & DATA_PORT;
maskhi |= DATA_PORT;
while (datlen--)
{
curbyte = *data++;
asm volatile
(
" ldi %0,8 \n\t" // 0
"loop%=:out %2, %3 \n\t" // 1
"lsl %1 \n\t" // 2
"dec %0 \n\t" // 3
" rjmp .+0 \n\t" // 5
" brcs .+2 \n\t" // 6l / 7h
" out %2,%4 \n\t" // 7l / -
" rjmp .+0 \n\t" // 9
" nop \n\t" // 10
" out %2,%4 \n\t" // 11
" breq end%= \n\t" // 12 nt. 13 taken
" rjmp .+0 \n\t" // 14
" rjmp .+0 \n\t" // 16
" rjmp .+0 \n\t" // 18
" rjmp loop%= \n\t" // 20
"end%=: \n\t"
: "=&d" (ctr)
: "r" (curbyte), "I" (_SFR_IO_ADDR(DATA_PORT)), "r" (maskhi), "r" (masklo)
);
}
}
//##############################################################################
// #
// End of program #
// #
//##############################################################################
The ATX PSU is rated for 36A and I think it is only pulling 18A when all the LED are set to white. Again, it works fine for green and blue. Mix them both to 100% and it looks correct. Mix anything with red and it starts getting strange.
Thanks for the help!
