mirror of
https://github.com/hyperion-project/hyperion.ng.git
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8d52466acd
should not be necessary because the number of LED's in a usual Lightberry setup is to low, but it's nice to have implemented. Former-commit-id: def3c46687670439be572e6b9c2dd1de5be2f1b5
275 lines
10 KiB
C++
275 lines
10 KiB
C++
// Arduino "bridge" code between host computer and WS2801-based digital
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// RGB LED pixels (e.g. Adafruit product ID #322). Intended for use
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// with USB-native boards such as Teensy or Adafruit 32u4 Breakout;
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// works on normal serial Arduinos, but throughput is severely limited.
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// LED data is streamed, not buffered, making this suitable for larger
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// installations (e.g. video wall, etc.) than could otherwise be held
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// in the Arduino's limited RAM.
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// Some effort is put into avoiding buffer underruns (where the output
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// side becomes starved of data). The WS2801 latch protocol, being
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// delay-based, could be inadvertently triggered if the USB bus or CPU
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// is swamped with other tasks. This code buffers incoming serial data
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// and introduces intentional pauses if there's a threat of the buffer
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// draining prematurely. The cost of this complexity is somewhat
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// reduced throughput, the gain is that most visual glitches are
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// avoided (though ultimately a function of the load on the USB bus and
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// host CPU, and out of our control).
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// LED data and clock lines are connected to the Arduino's SPI output.
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// On traditional Arduino boards, SPI data out is digital pin 11 and
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// clock is digital pin 13. On both Teensy and the 32u4 Breakout,
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// data out is pin B2, clock is B1. LEDs should be externally
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// powered -- trying to run any more than just a few off the Arduino's
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// 5V line is generally a Bad Idea. LED ground should also be
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// connected to Arduino ground.
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// --------------------------------------------------------------------
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// This file is part of Adalight.
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// Adalight is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation, either version 3 of
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// the License, or (at your option) any later version.
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// Adalight is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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// You should have received a copy of the GNU Lesser General Public
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// License along with Adalight. If not, see
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// <http://www.gnu.org/licenses/>.
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// --------------------------------------------------------------------
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#include <SPI.h>
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// LED pin for Adafruit 32u4 Breakout Board:
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//#define LED_DDR DDRE
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//#define LED_PORT PORTE
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//#define LED_PIN _BV(PORTE6)
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// LED pin for Teensy:
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//#define LED_DDR DDRD
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//#define LED_PORT PORTD
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//#define LED_PIN _BV(PORTD6)
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// LED pin for Arduino:
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#define LED_DDR DDRB
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#define LED_PORT PORTB
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#define LED_PIN _BV(PORTB5)
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// A 'magic word' (along with LED count & checksum) precedes each block
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// of LED data; this assists the microcontroller in syncing up with the
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// host-side software and properly issuing the latch (host I/O is
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// likely buffered, making usleep() unreliable for latch). You may see
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// an initial glitchy frame or two until the two come into alignment.
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// The magic word can be whatever sequence you like, but each character
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// should be unique, and frequent pixel values like 0 and 255 are
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// avoided -- fewer false positives. The host software will need to
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// generate a compatible header: immediately following the magic word
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// are three bytes: a 16-bit count of the number of LEDs (high byte
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// first) followed by a simple checksum value (high byte XOR low byte
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// XOR 0x55). LED data follows, 3 bytes per LED, in order R, G, B,
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// where 0 = off and 255 = max brightness.
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static const uint8_t magic[] = {'A', 'd', 'a'};
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#define MAGICSIZE sizeof(magic)
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#define HEADERSIZE (MAGICSIZE + 3)
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#define MODE_HEADER 0
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#define MODE_HOLD 1
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#define MODE_DATA 2
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#define DATA_LED A5
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#define SPI_LED A3
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// If no serial data is received for a while, the LEDs are shut off
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// automatically. This avoids the annoying "stuck pixel" look when
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// quitting LED display programs on the host computer.
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static const unsigned long serialTimeout = 15000; // 15 seconds
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void setup()
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{
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// Dirty trick: the circular buffer for serial data is 256 bytes,
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// and the "in" and "out" indices are unsigned 8-bit types -- this
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// much simplifies the cases where in/out need to "wrap around" the
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// beginning/end of the buffer. Otherwise there'd be a ton of bit-
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// masking and/or conditional code every time one of these indices
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// needs to change, slowing things down tremendously.
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uint8_t
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buffer[256],
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indexIn = 0,
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indexOut = 0,
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mode = MODE_HEADER,
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hi, lo, chk, i, spiFlag;
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int16_t
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bytesBuffered = 0,
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hold = 0,
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c;
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int32_t
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bytesRemaining;
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unsigned long
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startTime,
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lastByteTime,
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lastAckTime,
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t;
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bool
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data_in_led = false,
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spi_out_led = false;
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LED_DDR |= LED_PIN; // Enable output for LED
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LED_PORT &= ~LED_PIN; // LED off
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pinMode(DATA_LED, OUTPUT); //data in led
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pinMode(SPI_LED, OUTPUT); //data out led
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Serial.begin(115200); // Teensy/32u4 disregards baud rate; is OK!
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SPI.begin();
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SPI.setBitOrder(MSBFIRST);
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SPI.setDataMode(SPI_MODE0);
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SPI.setClockDivider(SPI_CLOCK_DIV8); // 2Mhz
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// Issue test pattern to LEDs on startup. This helps verify that
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// wiring between the Arduino and LEDs is correct. Not knowing the
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// actual number of LEDs connected, this sets all of them (well, up
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// to the first 25,000, so as not to be TOO time consuming) to red,
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// green, blue, then off. Once you're confident everything is working
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// end-to-end, it's OK to comment this out and reprogram the Arduino.
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uint8_t testcolor[] = { 0, 0, 0, 255, 0, 0 };
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for (char n = 3; n >= 0; n--) {
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for (int i = 0; i < 4; i++) { //Start Frame
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for (SPDR = 0x00; !(SPSR & _BV(SPIF)); );
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}
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for (c = 0; c < 25000; c++) {
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for (SPDR = 0xFF; !(SPSR & _BV(SPIF)); ); //Brightness byte
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for (i = 0; i < 3; i++) {
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for (SPDR = testcolor[n + i]; !(SPSR & _BV(SPIF)); ); //BGR
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}
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}
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for (int i = 0; i < 4; i++) { //Stop Frame
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for (SPDR = 0xFF; !(SPSR & _BV(SPIF)); );
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}
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delay(1); // One millisecond pause = latch
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}
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digitalWrite(SPI_LED, spi_out_led = !spi_out_led);
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Serial.print("Ada\n"); // Send ACK string to host
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startTime = micros();
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lastByteTime = lastAckTime = millis();
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// loop() is avoided as even that small bit of function overhead
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// has a measurable impact on this code's overall throughput.
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for (;;) {
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digitalWrite(DATA_LED, LOW);
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digitalWrite(SPI_LED, LOW);
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// Implementation is a simple finite-state machine.
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// Regardless of mode, check for serial input each time:
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t = millis();
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if ((bytesBuffered < 256) && ((c = Serial.read()) >= 0)) {
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buffer[indexIn++] = c;
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bytesBuffered++;
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lastByteTime = lastAckTime = t; // Reset timeout counters
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} else {
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// No data received. If this persists, send an ACK packet
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// to host once every second to alert it to our presence.
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if ((t - lastAckTime) > 1000) {
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Serial.print("Ada\n"); // Send ACK string to host
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lastAckTime = t; // Reset counter
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}
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// If no data received for an extended time, turn off all LEDs.
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if ((t - lastByteTime) > serialTimeout) {
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for (i = 0; i < 4; i++) { //Start Frame
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for (SPDR = 0x00; !(SPSR & _BV(SPIF)); );
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}
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for (c = 0; c < 25000; c++) {
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for (SPDR = 0xFF; !(SPSR & _BV(SPIF)); ); //Brightness Byte
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for (i = 0; i < 3; i++) {
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for (SPDR = 0x00; !(SPSR & _BV(SPIF)); ); //BGR
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}
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}
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for (i = 0; i < 4; i++) { //Stop Frame
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for (SPDR = 0xFF; !(SPSR & _BV(SPIF)); );
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}
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delay(1); // One millisecond pause = latch
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lastByteTime = t; // Reset counter
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}
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}
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switch (mode) {
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case MODE_HEADER:
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// In header-seeking mode. Is there enough data to check?
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if (bytesBuffered >= HEADERSIZE) {
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// Indeed. Check for a 'magic word' match.
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for (i = 0; (i < MAGICSIZE) && (buffer[indexOut++] == magic[i++]););
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if (i == MAGICSIZE) {
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// Magic word matches. Now how about the checksum?
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hi = buffer[indexOut++];
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lo = buffer[indexOut++];
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chk = buffer[indexOut++];
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if (chk == (hi ^ lo ^ 0x55)) {
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// Checksum looks valid. Get 16-bit LED count, add 1
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// (# LEDs is always > 0) and multiply by 3 for R,G,B.
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bytesRemaining = 4L * (256L * (long)hi + (long)lo) + 4L + (256L * (long)hi + (long)lo + 15) / 16;
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bytesBuffered -= 3;
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spiFlag = 0; // No data out yet
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mode = MODE_HOLD; // Proceed to latch wait mode
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digitalWrite(DATA_LED, data_in_led = !data_in_led);
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} else {
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// Checksum didn't match; search resumes after magic word.
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indexOut -= 3; // Rewind
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}
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} // else no header match. Resume at first mismatched byte.
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bytesBuffered -= i;
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}
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break;
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case MODE_HOLD:
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// Ostensibly "waiting for the latch from the prior frame
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// to complete" mode, but may also revert to this mode when
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// underrun prevention necessitates a delay.
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if ((micros() - startTime) < hold) break; // Still holding; keep buffering
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// Latch/delay complete. Advance to data-issuing mode...
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LED_PORT &= ~LED_PIN; // LED off
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mode = MODE_DATA; // ...and fall through (no break):
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case MODE_DATA:
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digitalWrite(SPI_LED, spi_out_led = !spi_out_led);
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while (spiFlag && !(SPSR & _BV(SPIF))); // Wait for prior byte
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if (bytesRemaining > 0) {
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if (bytesBuffered > 0) {
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SPDR = buffer[indexOut++]; // Issue next byte
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bytesBuffered--;
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bytesRemaining--;
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spiFlag = 1;
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}
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// If serial buffer is threatening to underrun, start
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// introducing progressively longer pauses to allow more
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// data to arrive (up to a point).
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if ((bytesBuffered < 32) && (bytesRemaining > bytesBuffered)) {
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startTime = micros();
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hold = 100 + (32 - bytesBuffered) * 10;
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mode = MODE_HOLD;
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}
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} else {
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// End of data -- issue latch:
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startTime = micros();
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hold = 1000; // Latch duration = 1000 uS
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LED_PORT |= LED_PIN; // LED on
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mode = MODE_HEADER; // Begin next header search
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}
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} // end switch
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} // end for(;;)
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}
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void loop()
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{
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// Not used. See note in setup() function.
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}
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