LCDGFX LCD display driver  2.0.1
This library is developed to control SSD1306/SSD1325/SSD1327/SSD1331/SSD1351/IL9163/PCD8554 RGB i2c/spi LED displays
v2/nano_engine/README.md
1 # Using NanoEngine for systems with low resources
2 
3 ***
4 
5 [tocstart]: # (toc start)
6 
7  * [Introduction](#introduction)
8  * [Main idea of NanoEngine](#main-idea-of-nanoengine)
9  * [Simple NanoEngine demo](#simple-nanoengine-demo)
10  * [Reading keys with NanoEngine](#reading-keys-with-nanoengine)
11  * [Draw monochrome bitmap](#draw-monochrome-bitmap)
12  * [Draw moving bitmap](#draw-moving-bitmap)
13  * [What if not to use draw callbacks](#what-if-not-to-use-draw-callbacks)
14  * [Using Adafruit GFX with NanoEngine](#using-adafruit-gfx-with-nanoengine)
15  * [To upper level](@ref index)
16 
17 [tocend]: # (toc end)
18 
19 <a name="introduction"></a>
20 ## Introduction
21 
22 Many applications use double-buffered output to physical display to avoid flickering effect, when a user observed non-completed picture for a short time. When working with color OLED/LCD displays like ssd1331, some micro-controllers do not have enough RAM to fit display buffer in. For example, in 8-bit mode ssd1331 OLED display needs 6144 bytes (`96*64`). But simple micro-controller like Atmega328 has only 2KiB, and Attiny85 has only 512B of RAM. But with ssd1306 library you still can create applications for those ones with good graphics.
23 ssd1306 library represents NanoEngine8, intended to be used with color OLED displays. Digit 8 means that engine implements 8-bit color mode. Refer to arkanoid8 as example, which can be run even on small Attiny85 with color ssd1331 display. The system supports NanoEngine1 for monochrome OLED displays, NanoEngine8 for 8-bit RGB OLED displays, NanoEngine16 for 16-bit RGB OLED displays.
24 
25 <a name="main-idea-of-nanoengine"></a>
26 ## Main idea of NanoEngine
27 
28 There are 2 issues with tiny controllers:
29  * they have a little RAM
30  * they support low frequencies
31 
32 The first problem is solved in NanoEngine by using double-buffer to redraw only part of display content at once. By default NanoEngine uses 8x8 small buffer (64 bytes) and 24 bytes to store information on areas, which need to be refreshed.
33 The second problem is solved almost the same way: refresh only those part of display content, which were changed since last frame update. For example, ssd1331 oled display work on SPI at 8MHz frequency, that means in ideal conditions the screen content can be refreshed 162 times per second (`8000000/(96*64*8)`). But with the data, you need to send also commands to the display and to do some other stuff. And real tests with Atmega328p show that `ssd1306_clearScreen()` can run only at 58 FPS, coping data from buffer to OLED memory runs slower.
34 There is no such issue for Arduboy, since it uses monochrome OLED ssd1306 with only 1KiB of RAM buffer, and theoretical fps can be up to 976. For color display and small controllers the main solution is to refresh only part of display content. Arkanoid8 can give easily 60 fps with NanoEngine8
35 
36 <a name="simple-nanoengine-demo"></a>
37 ## Simple NanoEngine demo
38 
39 ```cpp
40 #include "lcdgfx.h"
41 
42 NanoEngine8 engine;
43 
44 bool drawAll()
45 {
46  engine.canvas.clear();
47  engine.canvas.setColor(RGB_COLOR8(255,255,0));
48  engine.canvas.drawRect(15,12,70,55);
49  return true; // if to return false, the engine will skip this part of screen update
50 }
51 
52 void setup()
53 {
54  /* Init SPI 96x64 RBG oled. 3 - RESET, 4 - CS (can be omitted, oled CS must be pulled down), 5 - D/C */
55  ssd1331_96x64_spi_init(3, 4, 5);
56 
57  engine.begin();
58  engine.setFrameRate(30);
59  /* Set callback to draw parts, when NanoEngine8 asks */
60  engine.drawCallback( drawAll );
61 }
62 
63 void loop()
64 {
65  if (!engine.nextFrame()) return;
66  engine.refresh(); // Makes engine to refresh whole display content
67  engine.display();
68 }
69 ```
70 
71 <a name="reading-keys-with-nanoengine"></a>
72 ## Reading keys with NanoEngine
73 
74 What, if we want to move yellow rectangle. There is easy way to do this with NanoEngine8. The engine supports up-to 6 keys: `BUTTON_DOWN`, `BUTTON_LEFT`, `BUTTON_RIGHT`, `BUTTON_UP`, `BUTTON_A`, `BUTTON_B`. All you need is to say the engine how it can get buttons state on your board. There are already 2 built-in implementations: `connectArduboyKeys()` allows using Arduboy platform hardware (remember that you need to replace ssd1306 oled with color ssd1331 oled), and `connectZKeypad()` allows using standard 5-keys Z-keypad (you can find it on E-bay). Or you can set custom key processing handler via `connectCustomKeys()` and implement your own hardware driver.
75 
76 Example of using Z-keypad to move rectangle.
77 ```cpp
78 #include "lcdgfx.h"
79 
80 NanoEngine8 engine;
81 
82 NanoRect rect = { {15,12}, {60,35} }; // Lets make rect smaller than in previous example
83 
84 bool drawAll()
85 {
86  engine.canvas.clear();
87  engine.canvas.setColor(RGB_COLOR8(255,255,0));
88  engine.canvas.drawRect(rect); // draw rect in buffer
89  return true;
90 }
91 
92 void setup()
93 {
94  /* Init SPI 96x64 RBG oled. 3 - RESET, 4 - CS (can be omitted, oled CS must be pulled down), 5 - D/C */
95  ssd1331_96x64_spi_init(3, 4, 5);
96 
97  engine.begin();
98  engine.setFrameRate(30);
99  engine.drawCallback( drawAll ); // Set callback to draw parts, when NanoEngine8 asks
100  engine.connectZKeypad(0); // Connect ADC-buttons Z-keypad to analog A0 pin
101  engine.refresh(); // Makes engine to refresh whole display content at start-up
102 }
103 
104 void loop()
105 {
106  if (!engine.nextFrame()) return;
107  NanoPoint point = {0,0};
108  if (engine.pressed( BUTTON_RIGHT )) point.x = +1;
109  if (engine.pressed( BUTTON_LEFT )) point.x = -1;
110  if (engine.pressed( BUTTON_UP )) point.y = -1;
111  if (engine.pressed( BUTTON_DOWN )) point.y = +1;
112  engine.refresh(rect); // Update screen content at old rect position
113  rect += point; // Move rect according to pressed keys
114  engine.refresh(rect); // Update screen content at new rect position
115  engine.display(); // refresh display content
116 }
117 ```
118 
119 <a name="draw-monochrome-bitmap"></a>
120 ## Draw monochrome bitmap
121 
122 ```cpp
123 #include "lcdgfx.h"
124 
125 NanoEngine8 engine;
126 
127 const uint8_t heartSprite[8] PROGMEM =
128 {
129  0B00001110,
130  0B00011111,
131  0B00111111,
132  0B01111110,
133  0B01111110,
134  0B00111101,
135  0B00011001,
136  0B00001110
137 };
138 
139 bool drawAll()
140 {
141  engine.canvas.clear();
142  engine.canvas.setMode(0); // We want to draw non-transparent bitmap
143  engine.canvas.setColor(RGB_COLOR8(255,0,0)); // draw with red color
144  engine.canvas.drawBitmap1(10, 20, 8, 8, heartSprite);
145  return true;
146 }
147 
148 void setup()
149 {
150  /* Init SPI 96x64 RBG oled. 3 - RESET, 4 - CS (can be omitted, oled CS must be pulled down), 5 - D/C */
151  ssd1331_96x64_spi_init(3, 4, 5);
152  engine.begin();
153  engine.drawCallback( drawAll ); // Set callback to draw parts, when NanoEngine8 asks
154  engine.refresh(); // Makes engine to refresh whole display content at start-up
155 }
156 
157 void loop()
158 {
159  if (!engine.nextFrame()) return;
160  engine.display(); // refresh display content
161 }
162 ```
163 
164 <a name="draw-moving-bitmap"></a>
165 ## Draw moving bitmap
166 
167 In some applications like games, there is need to move bitmaps. It is easy to do this with ssd1306 library using NanoSprite objects. NanoSprite object is responsible for refreshing areas, touched by sprite. So, you need only to move sprite, where you want, the engine will take care of updating display content.
168 
169 ```cpp
170 #include "lcdgfx.h"
171 
172 const uint8_t heartSprite[8] PROGMEM =
173 {
174  0B00001110,
175  0B00011111,
176  0B00111111,
177  0B01111110,
178  0B01111110,
179  0B00111101,
180  0B00011001,
181  0B00001110
182 };
183 
184 NanoEngine8 engine;
185 NanoSprite<NanoEngine8, engine> sprite( {0, 0}, {8, 8}, heartSprite );
186 
187 bool drawAll()
188 {
189  engine.canvas.clear();
190  engine.canvas.setMode(0); // We want to draw non-transparent bitmap
191  engine.canvas.setColor(RGB_COLOR8(255,0,0)); // draw with red color
192  sprite.draw();
193  return true;
194 }
195 
196 void setup()
197 {
198  /* Init SPI 96x64 RBG oled. 3 - RESET, 4 - CS (can be omitted, oled CS must be pulled down), 5 - D/C */
199  ssd1331_96x64_spi_init(3, 4, 5);
200  engine.begin();
201  engine.drawCallback( drawAll ); // Set callback to draw parts, when NanoEngine8 asks
202  engine.refresh(); // Makes engine to refresh whole display content at start-up
203 }
204 
205 void loop()
206 {
207  if (!engine.nextFrame()) return;
208  // You will see horizontal flying heart
209  sprite.moveBy( { 1, 0 } );
210  engine.display(); // refresh display content
211 }
212 ```
213 
214 <a name="what-if-not-to-use-draw-callbacks"></a>
215 ## What if not to use draw callbacks
216 
217 If you don't want to use draw callbacks in your application, but still need a power of NanoEngine, then there is one way for you: to use full-screen double-buffering with NanoEngine. The example, you will find below, shows how to use full-screen double buffering for monochrome 128x64 ssd1306 oled display. This example can be run on Atmega328p and more powerful micro controllers. It clears back-buffer every time engine says to redraw the frame. But you can preserve previously prepared image by removing call to `engine.canvas.clear()`.
218 
219 ```cpp
220 #include "lcdgfx.h"
221 
222 NanoEngine<BUFFER_128x64_MONO> engine;
223 
224 void setup()
225 {
226  // Init SPI 128x64 monochrome oled.
227  // 3 - RESET, 4 - CS (can be omitted, oled CS must be pulled down), 5 - D/C
228  ssd1306_128x64_spi_init(3, 4, 5);
229 
230  engine.begin();
231  engine.setFrameRate(30);
232 }
233 
234 void loop()
235 {
236  if (!engine.nextFrame()) return;
237  engine.canvas.clear(); // This step can be removed, if you don't want to clear buffer
238  engine.canvas.drawRect(15,12,70,55);
239  engine.display();
240 }
241 ```
242 
243 <a name="using-adafruit-gfx-with-nanoengine"></a>
244 ## Using Adafruit GFX with NanoEngine
245 
246 Many developers are familiar with nice AdafruitGFX library. It provides rich set of graphics functions. Starting with 1.7.0 ssd1306 library it is possible to use AdafruiGFX api in combination with NanoEngine. And it is really easy.
247 You need to remember only, that AdafruitGFX uses different approach, when working with rectangles and monochrome images. NanoCanvas expects monochrome bitmaps in native ssd1306 format, while Adafruit uses more native format for human. If you compare an example below with examples above you will understand, what's the difference (heartImage). Refer to AdafruitGFX documentation.
248 
249 ```cpp
250 // Define this before including library header, this will give Adafruit GFX support
251 // !!! Don't forget to install AdafruitGFX library to your Arduino IDE !!!
252 #define CONFIG_ADAFRUIT_GFX_ENABLE
253 
254 #include "lcdgfx.h"
255 
256 // Now you can use AdafruitGFX by referencing engine.canvas
257 NanoEngine<ADATILE_8x8_RGB8> engine;
258 
259 const PROGMEM uint8_t heartImage[8] =
260 {
261  0B01100110,
262  0B11111001,
263  0B11111101,
264  0B11111111,
265  0B01111110,
266  0B00111100,
267  0B00011000,
268  0B00000000
269 };
270 
271 bool drawAll()
272 {
273  engine.canvas.fillScreen( 0 );
274  engine.canvas.drawBitmap(10, 20, heartSprite, 8, 8, RGB_COLOR8(255,0,0)); // draw bitmap with red color
275  return true;
276 }
277 
278 void setup()
279 {
280  /* Init SPI 96x64 RBG oled. 3 - RESET, 4 - CS (can be omitted, oled CS must be pulled down), 5 - D/C */
281  ssd1331_96x64_spi_init(3, 4, 5);
282  engine.begin();
283  engine.drawCallback( drawAll ); // Set callback to draw parts, when NanoEngine8 asks
284  engine.refresh(); // Makes engine to refresh whole display content at start-up
285 }
286 
287 void loop()
288 {
289  if (!engine.nextFrame()) return;
290  engine.display(); // refresh display content
291 }
292 ```
293