// Arduino "bridge" code between host computer and WS2801-based digital
// RGB LED pixels (e.g. Adafruit product ID #322). Intended for use
// with USB-native boards such as Teensy or Adafruit 32u4 Breakout;
// works on normal serial Arduinos, but throughput is severely limited.
// LED data is streamed, not buffered, making this suitable for larger
// installations (e.g. video wall, etc.) than could otherwise be held
// in the Arduino's limited RAM.
// Some effort is put into avoiding buffer underruns (where the output
// side becomes starved of data). The WS2801 latch protocol, being
// delay-based, could be inadvertently triggered if the USB bus or CPU
// is swamped with other tasks. This code buffers incoming serial data
// and introduces intentional pauses if there's a threat of the buffer
// draining prematurely. The cost of this complexity is somewhat
// reduced throughput, the gain is that most visual glitches are
// avoided (though ultimately a function of the load on the USB bus and
// host CPU, and out of our control).
// LED data and clock lines are connected to the Arduino's SPI output.
// On traditional Arduino boards, SPI data out is digital pin 11 and
// clock is digital pin 13. On both Teensy and the 32u4 Breakout,
// data out is pin B2, clock is B1. LEDs should be externally
// powered -- trying to run any more than just a few off the Arduino's
// 5V line is generally a Bad Idea. LED ground should also be
// connected to Arduino ground.
// --------------------------------------------------------------------
// This file is part of Adalight.
// Adalight is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of
// the License, or (at your option) any later version.
// Adalight is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
// You should have received a copy of the GNU Lesser General Public
// License along with Adalight. If not, see
// <http://www.gnu.org/licenses/>.
// --------------------------------------------------------------------
#include <SPI.h>
// LED pin for Adafruit 32u4 Breakout Board:
//#define LED_DDR DDRE
//#define LED_PORT PORTE
//#define LED_PIN _BV(PORTE6)
// LED pin for Teensy:
//#define LED_DDR DDRD
//#define LED_PORT PORTD
//#define LED_PIN _BV(PORTD6)
// LED pin for Arduino:
#define LED_DDR DDRB
#define LED_PORT PORTB
#define LED_PIN _BV(PORTB5)
// A 'magic word' (along with LED count & checksum) precedes each block
// of LED data; this assists the microcontroller in syncing up with the
// host-side software and properly issuing the latch (host I/O is
// likely buffered, making usleep() unreliable for latch). You may see
// an initial glitchy frame or two until the two come into alignment.
// The magic word can be whatever sequence you like, but each character
// should be unique, and frequent pixel values like 0 and 255 are
// avoided -- fewer false positives. The host software will need to
// generate a compatible header: immediately following the magic word
// are three bytes: a 16-bit count of the number of LEDs (high byte
// first) followed by a simple checksum value (high byte XOR low byte
// XOR 0x55). LED data follows, 3 bytes per LED, in order R, G, B,
// where 0 = off and 255 = max brightness.
static const uint8_t magic[] = {'A','d','a'};
#define MAGICSIZE sizeof(magic)
#define HEADERSIZE (MAGICSIZE + 3)
#define MODE_HEADER 0
#define MODE_HOLD 1
#define MODE_DATA 2
// If no serial data is received for a while, the LEDs are shut off
// automatically. This avoids the annoying "stuck pixel" look when
// quitting LED display programs on the host computer.
static const unsigned long serialTimeout = 15000; // 15 seconds
void setup()
{
// Dirty trick: the circular buffer for serial data is 256 bytes,
// and the "in" and "out" indices are unsigned 8-bit types -- this
// much simplifies the cases where in/out need to "wrap around" the
// beginning/end of the buffer. Otherwise there'd be a ton of bit-
// masking and/or conditional code every time one of these indices
// needs to change, slowing things down tremendously.
uint8_t
buffer[256],
indexIn = 0,
indexOut = 0,
mode = MODE_HEADER,
hi, lo, chk, i, spiFlag;
int16_t
bytesBuffered = 0,
hold = 0,
c;
int32_t
bytesRemaining;
unsigned long
startTime,
lastByteTime,
lastAckTime,
t;
LED_DDR |= LED_PIN; // Enable output for LED
LED_PORT &= ~LED_PIN; // LED off
Serial.begin(115200); // Teensy/32u4 disregards baud rate; is OK!
SPI.begin();
SPI.setBitOrder(MSBFIRST);
SPI.setDataMode(SPI_MODE0);
SPI.setClockDivider(SPI_CLOCK_DIV16); // 1 MHz max, else flicker
// Issue test pattern to LEDs on startup. This helps verify that
// wiring between the Arduino and LEDs is correct. Not knowing the
// actual number of LEDs connected, this sets all of them (well, up
// to the first 25,000, so as not to be TOO time consuming) to red,
// green, blue, then off. Once you're confident everything is working
// end-to-end, it's OK to comment this out and reprogram the Arduino.
uint8_t testcolor[] = { 0, 0, 0, 255, 0, 0 };
for(char n=3; n>=0; n--) {
for(c=0; c<25000; c++) {
for(i=0; i<3; i++) {
for(SPDR = testcolor[n + i]; !(SPSR & _BV(SPIF)); );
}
}
delay(1); // One millisecond pause = latch
}
Serial.print("Ada\n"); // Send ACK string to host
startTime = micros();
lastByteTime = lastAckTime = millis();
// loop() is avoided as even that small bit of function overhead
// has a measurable impact on this code's overall throughput.
for(;;) {
// Implementation is a simple finite-state machine.
// Regardless of mode, check for serial input each time:
t = millis();
if((bytesBuffered < 256) && ((c = Serial.read()) >= 0)) {
buffer[indexIn++] = c;
bytesBuffered++;
lastByteTime = lastAckTime = t; // Reset timeout counters
} else {
// No data received. If this persists, send an ACK packet
// to host once every second to alert it to our presence.
if((t - lastAckTime) > 1000) {
Serial.print("Ada\n"); // Send ACK string to host
lastAckTime = t; // Reset counter
}
// If no data received for an extended time, turn off all LEDs.
if((t - lastByteTime) > serialTimeout) {
for(c=0; c<32767; c++) {
for(SPDR=0; !(SPSR & _BV(SPIF)); );
}
delay(1); // One millisecond pause = latch
lastByteTime = t; // Reset counter
}
}
switch(mode) {
case MODE_HEADER:
// In header-seeking mode. Is there enough data to check?
if(bytesBuffered >= HEADERSIZE) {
// Indeed. Check for a 'magic word' match.
for(i=0; (i<MAGICSIZE) && (buffer[indexOut++] == magic[i++]););
if(i == MAGICSIZE) {
// Magic word matches. Now how about the checksum?
hi = buffer[indexOut++];
lo = buffer[indexOut++];
chk = buffer[indexOut++];
if(chk == (hi ^ lo ^ 0x55)) {
// Checksum looks valid. Get 16-bit LED count, add 1
// (# LEDs is always > 0) and multiply by 3 for R,G,B.
bytesRemaining = 3L * (256L * (long)hi + (long)lo + 1L);
bytesBuffered -= 3;
spiFlag = 0; // No data out yet
mode = MODE_HOLD; // Proceed to latch wait mode
} else {
// Checksum didn't match; search resumes after magic word.
indexOut -= 3; // Rewind
}
} // else no header match. Resume at first mismatched byte.
bytesBuffered -= i;
}
break;
case MODE_HOLD:
// Ostensibly "waiting for the latch from the prior frame
// to complete" mode, but may also revert to this mode when
// underrun prevention necessitates a delay.
if((micros() - startTime) < hold) break; // Still holding; keep buffering
// Latch/delay complete. Advance to data-issuing mode...
LED_PORT &= ~LED_PIN; // LED off
mode = MODE_DATA; // ...and fall through (no break):
case MODE_DATA:
while(spiFlag && !(SPSR & _BV(SPIF))); // Wait for prior byte
if(bytesRemaining > 0) {
if(bytesBuffered > 0) {
SPDR = buffer[indexOut++]; // Issue next byte
bytesBuffered--;
bytesRemaining--;
spiFlag = 1;
}
// If serial buffer is threatening to underrun, start
// introducing progressively longer pauses to allow more
// data to arrive (up to a point).
if((bytesBuffered < 32) && (bytesRemaining > bytesBuffered)) {
startTime = micros();
hold = 100 + (32 - bytesBuffered) * 10;
mode = MODE_HOLD;
}
} else {
// End of data -- issue latch:
startTime = micros();
hold = 1000; // Latch duration = 1000 uS
LED_PORT |= LED_PIN; // LED on
mode = MODE_HEADER; // Begin next header search
}
} // end switch
} // end for(;;)
}
void loop()
{
// Not used. See note in setup() function.
}
wollt ich auch aber
(Skizze von einem Schaltplan für meine Ministeuerung vll 
, 1 LED geht noch gerade bei 40Zoll das alles so quasi "flavored by color in room" ist nur so hintergrund bissl einpassen ... mehr solls nicht sein weil immer eine weisse Wand ist manchmal langweilig, je nach Film....
eigentlich muss die LED ja nur an den 3 Ports angeklemmt werden und das XBMC Plugin aktiviert werden oder ? ist doch im Prinzip nichts andres wie wenn ich eine LED ans Arduino klemme oder doch ?! :S :/
