DMD.cpp

/*
 * Copyright (C) 2012 Southern Storm Software, Pty Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include "DMD.h"
#if defined(ARDUINO) && ARDUINO >= 100
#include <Arduino.h>
#else
#include <WProgram.h>
#endif
#include <pins_arduino.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <string.h>
#include <stdlib.h>

// Pins on the DMD connector board.
#define DMD_PIN_PHASE_LSB       6       // A
#define DMD_PIN_PHASE_MSB       7       // B
#define DMD_PIN_LATCH           8       // SCLK
#define DMD_PIN_OUTPUT_ENABLE   9       // nOE
#define DMD_PIN_SPI_SS          SS      // SPI Slave Select
#define DMD_PIN_SPI_MOSI        MOSI    // SPI Master Out, Slave In (R)
#define DMD_PIN_SPI_MISO        MISO    // SPI Master In, Slave Out
#define DMD_PIN_SPI_SCK         SCK     // SPI Serial Clock (CLK)

// Dimension information for the display.
#define DMD_NUM_COLUMNS         32      // Number of columns in a panel.
#define DMD_NUM_ROWS            16      // Number of rows in a panel.

// Refresh times.
#define DMD_REFRESH_MS          5
#define DMD_REFRESH_US          5000

DMD::DMD(int widthPanels, int heightPanels)
    : Bitmap(widthPanels * DMD_NUM_COLUMNS, heightPanels * DMD_NUM_ROWS)
    , _doubleBuffer(false)
    , phase(0)
    , fb0(0)
    , fb1(0)
    , displayfb(0)
    , lastRefresh(millis())
{
    // Both rendering and display are to fb0 initially.
    fb0 = displayfb = fb;

    // Initialize SPI to MSB-first, mode 0, clock divider = 2.
    pinMode(DMD_PIN_SPI_SCK, OUTPUT);
    pinMode(DMD_PIN_SPI_MOSI, OUTPUT);
    pinMode(DMD_PIN_SPI_SS, OUTPUT);
    digitalWrite(DMD_PIN_SPI_SCK, LOW);
    digitalWrite(DMD_PIN_SPI_MOSI, LOW);
    digitalWrite(DMD_PIN_SPI_SS, HIGH);
    SPCR |= _BV(MSTR);
    SPCR |= _BV(SPE);
    SPCR &= ~(_BV(DORD));   // MSB-first
    SPCR &= ~0x0C;          // Mode 0
    SPCR &= ~0x03;          // Clock divider rate 2
    SPSR |= 0x01;           // MSB of clock divider rate

    // Initialize the DMD-specific pins.
    pinMode(DMD_PIN_PHASE_LSB, OUTPUT);
    pinMode(DMD_PIN_PHASE_MSB, OUTPUT);
    pinMode(DMD_PIN_LATCH, OUTPUT);
    pinMode(DMD_PIN_OUTPUT_ENABLE, OUTPUT);
    digitalWrite(DMD_PIN_PHASE_LSB, LOW);
    digitalWrite(DMD_PIN_PHASE_MSB, LOW);
    digitalWrite(DMD_PIN_LATCH, LOW);
    digitalWrite(DMD_PIN_OUTPUT_ENABLE, LOW);
    digitalWrite(DMD_PIN_SPI_MOSI, HIGH);
}

DMD::~DMD()
{
    if (fb0)
        free(fb0);
    if (fb1)
        free(fb1);
    fb = 0; // Don't free the buffer again in the base class.
}

void DMD::setDoubleBuffer(bool doubleBuffer)
{
    if (doubleBuffer != _doubleBuffer) {
        _doubleBuffer = doubleBuffer;
        if (doubleBuffer) {
            // Allocate a new back buffer.
            unsigned int size = _stride * _height;
            fb1 = (uint8_t *)malloc(size);

            // Clear the new back buffer and then switch to it, leaving
            // the current contents of fb0 on the screen.
            if (fb1) {
                memset(fb1, 0xFF, size);
                cli();
                fb = fb1;
                displayfb = fb0;
                sei();
            } else {
                // Failed to allocate the memory, so revert to single-buffered.
                _doubleBuffer = false;
            }
        } else if (fb1) {
            // Disabling double-buffering, so forcibly switch to fb0.
            cli();
            fb = fb0;
            displayfb = fb0;
            sei();

            // Free the unnecessary buffer.
            free(fb1);
            fb1 = 0;
        }
    }
}

void DMD::swapBuffers()
{
    if (_doubleBuffer) {
        // Turn off interrupts while swapping buffers so that we don't
        // accidentally try to refresh() in the middle of this code.
        cli();
        if (fb == fb0) {
            fb = fb1;
            displayfb = fb0;
        } else {
            fb = fb0;
            displayfb = fb1;
        }
        sei();
    }
}

void DMD::swapBuffersAndCopy()
{
    swapBuffers();
    if (_doubleBuffer)
        memcpy(fb, displayfb, _stride * _height);
}

void DMD::loop()
{
    unsigned long currentTime = millis();
    if ((currentTime - lastRefresh) >= DMD_REFRESH_MS) {
        lastRefresh = currentTime;
        refresh();
    }
}

// Send a single byte via SPI.
static inline void spiSend(byte value)
{
    SPDR = value;
    while (!(SPSR & _BV(SPIF)))
        ;   // Wait for the transfer to complete.
}

// Flip the bits in a byte.  Table generated by genflip.c
static const uint8_t flipBits[256] PROGMEM = {
    0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0,
    0x30, 0xB0, 0x70, 0xF0, 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8,
    0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, 0x04, 0x84, 0x44, 0xC4,
    0x24, 0xA4, 0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4,
    0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC,
    0x3C, 0xBC, 0x7C, 0xFC, 0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2,
    0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, 0x0A, 0x8A, 0x4A, 0xCA,
    0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
    0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6,
    0x36, 0xB6, 0x76, 0xF6, 0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE,
    0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, 0x01, 0x81, 0x41, 0xC1,
    0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
    0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9,
    0x39, 0xB9, 0x79, 0xF9, 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5,
    0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5, 0x0D, 0x8D, 0x4D, 0xCD,
    0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
    0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3,
    0x33, 0xB3, 0x73, 0xF3, 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB,
    0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB, 0x07, 0x87, 0x47, 0xC7,
    0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7,
    0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, 0x1F, 0x9F, 0x5F, 0xDF,
    0x3F, 0xBF, 0x7F, 0xFF
};

void DMD::refresh()
{
    // Bail out if there is a conflict on the SPI bus.
    if (!digitalRead(DMD_PIN_SPI_SS))
        return;

    // Transfer the data for the next group of interleaved rows.
    int stride4 = _stride * 4;
    uint8_t *data0;
    uint8_t *data1;
    uint8_t *data2;
    uint8_t *data3;
    bool flipRow = ((_height & 0x10) == 0);
    for (int y = 0; y < _height; y += 16) {
        if (!flipRow) {
            // The panels in this row are the right way up.
            data0 = displayfb + _stride * (y + phase);
            data1 = data0 + stride4;
            data2 = data1 + stride4;
            data3 = data2 + stride4;
            for (int x = _stride; x > 0; --x) {
                spiSend(*data3++);
                spiSend(*data2++);
                spiSend(*data1++);
                spiSend(*data0++);
            }
            flipRow = true;
        } else {
            // The panels in this row are upside-down and reversed.
            data0 = displayfb + _stride * (y + 16 - phase) - 1;
            data1 = data0 - stride4;
            data2 = data1 - stride4;
            data3 = data2 - stride4;
            for (int x = _stride; x > 0; --x) {
                spiSend(pgm_read_byte(&(flipBits[*data3--])));
                spiSend(pgm_read_byte(&(flipBits[*data2--])));
                spiSend(pgm_read_byte(&(flipBits[*data1--])));
                spiSend(pgm_read_byte(&(flipBits[*data0--])));
            }
            flipRow = false;
        }
    }

    // Latch the data from the shift registers onto the actual display.
    digitalWrite(DMD_PIN_OUTPUT_ENABLE, LOW);
    digitalWrite(DMD_PIN_LATCH, HIGH);
    digitalWrite(DMD_PIN_LATCH, LOW);
    if (phase & 0x02)
        digitalWrite(DMD_PIN_PHASE_MSB, HIGH);
    else
        digitalWrite(DMD_PIN_PHASE_MSB, LOW);
    if (phase & 0x01)
        digitalWrite(DMD_PIN_PHASE_LSB, HIGH);
    else
        digitalWrite(DMD_PIN_PHASE_LSB, LOW);
    digitalWrite(DMD_PIN_OUTPUT_ENABLE, HIGH);
    phase = (phase + 1) & 0x03;
}

void DMD::enableTimer1()
{
    // Number of CPU cycles in the display's refresh period.
    unsigned long numCycles = (F_CPU / 2000000) * DMD_REFRESH_US;

    // Determine the prescaler to be used.
    #define TIMER1_RESOLUTION  65536UL
    uint8_t prescaler;
    if (numCycles < TIMER1_RESOLUTION) {
        // No prescaling required.
        prescaler = _BV(CS10);
    } else if (numCycles < TIMER1_RESOLUTION * 8) {
        // Prescaler = 8.
        prescaler = _BV(CS11);
        numCycles >>= 3;
    } else if (numCycles < TIMER1_RESOLUTION * 64) {
        // Prescaler = 64.
        prescaler = _BV(CS11) | _BV(CS10);
        numCycles >>= 6;
    } else if (numCycles < TIMER1_RESOLUTION * 256) {
        // Prescaler = 256.
        prescaler = _BV(CS12);
        numCycles >>= 8;
    } else if (numCycles < TIMER1_RESOLUTION * 1024) {
        // Prescaler = 1024.
        prescaler = _BV(CS12) | _BV(CS10);
        numCycles >>= 10;
    } else {
        // Too long, so set the maximum timeout.
        prescaler = _BV(CS12) | _BV(CS10);
        numCycles = TIMER1_RESOLUTION - 1;
    }

    // Configure Timer1 for the period we want.
    TCCR1A = 0;
    TCCR1B = _BV(WGM13);
    uint8_t saveSREG = SREG;
    cli();
    ICR1 = numCycles;
    SREG = saveSREG;    // Implicit sei() if interrupts were on previously.
    TCCR1B = (TCCR1B & ~(_BV(CS12) | _BV(CS11) | _BV(CS10))) | prescaler;

    // Turn on the Timer1 overflow interrupt.
    TIMSK1 |= _BV(TOIE1);
}

void DMD::disableTimer1()
{
    // Turn off the Timer1 overflow interrupt.
    TIMSK1 &= ~_BV(TOIE1);
}

DMD::Color DMD::fromRGB(uint8_t r, uint8_t g, uint8_t b)
{
    if (r || g || b)
        return White;
    else
        return Black;
}