Goliath Fall 2017 – LED Grid Display

Designed specifically to work with the Adafruit LED Matrix backpacks
----> http://www.adafruit.com/products/
----> http://www.adafruit.com/products/

These displays use I2C to communicate, 2 pins are required to
interface. There are multiple selectable I2C addresses. For backpacks
with 2 Address Select pins: 0x70, 0x71, 0x72 or 0x73. For backpacks
with 3 Address Select pins: 0x70 thru 0x77

Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!

Written by Limor Fried/Ladyada for Adafruit Industries.
MIT license, all text above must be included in any redistribution
****************************************************/

#include <Wire.h>

#include "Adafruit_LEDBackpackCom.h"

#ifndef _BV
#define _BV(bit) (1<<(bit))
#endif

#ifndef _swap_int16_t
#define _swap_int16_t(a, b) { int16_t t = a; a = b; b = t; }
#endif

void Adafruit_LEDBackpack::setBrightness(uint8_t b) {
if (b > 15) b = 15;
Wire.beginTransmission(i2c_addr);
Wire.write(HT16K33_CMD_BRIGHTNESS | b);
Wire.endTransmission();
}

void Adafruit_LEDBackpack::blinkRate(uint8_t b) {
Wire.beginTransmission(i2c_addr);
if (b > 3) b = 0; // turn off if not sure

Wire.write(HT16K33_BLINK_CMD | HT16K33_BLINK_DISPLAYON | (b << 1));
Wire.endTransmission();
}

Adafruit_LEDBackpack::Adafruit_LEDBackpack(void) {
}

void Adafruit_LEDBackpack::begin(uint8_t _addr = 0x70) {
i2c_addr = _addr;

Wire.begin();

Wire.beginTransmission(i2c_addr);
Wire.write(0x21); // turn on oscillator
Wire.endTransmission();
blinkRate(HT16K33_BLINK_OFF);

setBrightness(15); // max brightness
}

void Adafruit_LEDBackpack::writeDisplay(void) {
Wire.beginTransmission(i2c_addr);
Wire.write((uint8_t)0x00); // start at address $00

for (uint8_t i=0; i<8; i++) {
Wire.write(displaybuffer[i] & 0xFF);
Wire.write(displaybuffer[i] >> 8);
}
Wire.endTransmission();
}

void Adafruit_LEDBackpack::clear(void) {
for (uint8_t i=0; i<8; i++) {
displaybuffer[i] = 0;
}
}

Adafruit_8x8matrix::Adafruit_8x8matrix(void) {
}

void Adafruit_8x8matrix::drawPixel(int16_t x, int16_t y, uint16_t color, uint8_t a) {
if ((y < 0) || (y >= 8)) return;
if ((x < 0) || (x >= 8)) return;

// check rotation, move pixel around if necessary
switch (a) {
case 1:
_swap_int16_t(x, y);
x = 8 - x - 1;
break;
case 2:
x = 8 - x - 1;
y = 8 - y - 1;
break;
case 3:
_swap_int16_t(x, y);
y = 8 - y - 1;
break;
}
// wrap around the x
x += 7;
x %= 8;

if (color) {
displaybuffer[y] |= 1 << x;
} else {
displaybuffer[y] &= ~(1 << x);
}
}

void Adafruit_8x8matrix::drawLine(int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color) {
int16_t steep = abs(y1 - y0) > abs(x1 - x0);
if (steep) {
_swap_int16_t(x0, y0);
_swap_int16_t(x1, y1);
}

if (x0 > x1) {
_swap_int16_t(x0, x1);
_swap_int16_t(y0, y1);
}

int16_t dx, dy;
dx = x1 - x0;
dy = abs(y1 - y0);

int16_t err = dx / 2;
int16_t ystep;

if (y0 < y1) {
ystep = 1;
} else {
ystep = -1;
}