1 /* 2 * Generate a VGA signal using a PIC32 microcontroller. 3 * 4 * Copyright (C) 2017, 2018 Paul Boddie <paul@boddie.org.uk> 5 * 6 * This program is free software: you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation, either version 3 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program. If not, see <http://www.gnu.org/licenses/>. 18 */ 19 20 21 #include "pic32_c.h" 22 #include "init.h" 23 #include "debug.h" 24 25 /* Specific functionality. */ 26 27 #include "devconfig.h" 28 #include "display.h" 29 #include "display_config.h" 30 #include "font.h" 31 #include "main.h" 32 #include "vga.h" 33 #include "vga_display.h" 34 35 36 37 /* Define DMA channels if not indicated in the build configuration. */ 38 39 /* CPU-based transfers: no channels. */ 40 41 #ifdef TRANSFER_CPU 42 #define LINE_CHANNELS 0 43 #define SCROLL_XSTEP 1 44 45 /* DMA-based transfers: single channel by default. */ 46 47 #else 48 49 #ifndef LINE_CHANNELS 50 #define LINE_CHANNELS 1 51 #endif 52 53 #define SCROLL_XSTEP LINE_CHANNELS 54 #endif 55 56 57 58 /* Define timers if not indicated in the build configuration. */ 59 60 #ifndef LINE_TIMER 61 #define LINE_TIMER 2 62 #endif 63 64 #ifndef TRANSFER_TIMER 65 #define TRANSFER_TIMER 0 66 #endif 67 68 /* Define different output ports and pins for parallel mode. */ 69 70 #ifndef PARALLEL_MODE 71 #define VGA_OUTPUT PORTB 72 #define OC1_PIN RPA0R 73 #define OC2_PIN RPA1R 74 #define LED_PIN (1 << 3) 75 #else 76 #define VGA_OUTPUT PM_REG(0, PMxDIN) 77 #define OC1_PIN RPB4R 78 #define OC2_PIN RPB5R 79 #define LED_PIN (1 << 2) 80 #endif 81 82 83 84 /* Framebuffer memory. */ 85 86 static uint8_t framebuffer[FRAME_SIZE * FRAME_COUNT]; 87 88 89 90 /* Bundled image and font data. */ 91 92 extern uint8_t screendata[]; 93 extern uint32_t screendata_width, screendata_height; 94 extern uint8_t sprite[]; 95 extern uint32_t sprite_width, sprite_height; 96 97 extern uint8_t fontchars[]; 98 extern uint32_t fonttable[]; 99 extern uint32_t fontbase, fontlimit; 100 101 static font_config_t font_config; 102 103 104 105 /* Busy wait. */ 106 107 static void wait(uint32_t delay) 108 { 109 uint32_t counter = delay; 110 111 if (!delay) return; 112 while (counter--) __asm__(""); /* retain loop */ 113 } 114 115 /* Blink an attached LED with delays implemented using a loop. */ 116 117 static void blink(uint32_t delay, uint32_t port, uint32_t pins) 118 { 119 /* Clear outputs (LED). */ 120 121 CLR_REG(port, pins); 122 123 while (1) 124 { 125 wait(delay); 126 127 /* Invert outputs (LED). */ 128 129 INV_REG(port, pins); 130 } 131 } 132 133 /* Move a sprite around on the framebuffer. */ 134 135 static void animate(uint32_t delay) 136 { 137 /* Stored region behind the sprite. */ 138 139 uint8_t background[sprite_width * sprite_height]; 140 141 /* Sprite position. */ 142 143 int x, y; 144 145 /* Scrolling directions. */ 146 147 int dir[] = {1, 0, -1, 0, 1}, i = 0; 148 149 /* Scrolling position. */ 150 151 int xorigin = 0, yorigin = 0; 152 153 /* Replotted column details. */ 154 155 int width, column_width, xsource, xdisplay; 156 157 while (1) 158 { 159 for (y = 0; y < screendata_height - sprite_height; y++) 160 { 161 for (x = 0; x < screendata_width - sprite_width; x++) 162 { 163 /* Copy to the store from the display, then blit the image. */ 164 165 copy_display(&display_config, background, 166 sprite_width, sprite_height, 167 x, y, -1, 0); 168 copy_display(&display_config, sprite, 169 sprite_width, sprite_height, 170 x, y, 0x8c, 1); 171 172 /* Update the display with the frame details. */ 173 174 vga_set_frame(&display_config); 175 wait(delay); 176 177 /* Copy to the display from the store, restoring the original 178 background. */ 179 180 copy_display(&display_config, background, 181 sprite_width, sprite_height, 182 x, y, -1, 1); 183 184 /* Scroll in the indicated direction. */ 185 186 scroll_display(&display_config, dir[i], dir[i + 1]); 187 188 /* Update the vertical origin if appropriate. */ 189 190 if (dir[i + 1]) 191 { 192 yorigin += dir[i + 1]; 193 194 if (yorigin < 0) 195 yorigin += screendata_height; 196 else if (yorigin >= screendata_height) 197 yorigin -= screendata_height; 198 } 199 200 /* For horizontal scrolling, plot the exposed column at the left 201 (if scrolling left) or at the right (if scrolling right). */ 202 203 if (dir[i]) 204 { 205 /* Due to the effect of a simple screen start increment in 206 the dual channel configuration, horizontal scrolling 207 involves two pixel increments and thus requires a two- 208 pixel column to be plotted. */ 209 210 width = dir[i] * SCROLL_XSTEP; 211 column_width = width < 0 ? -width : width; 212 213 /* Plot either at the left or right edge. */ 214 215 xdisplay = width < 0 ? 0 : screendata_width - width; 216 217 /* Determine the location of the column to be plotted. */ 218 219 xorigin += width; 220 221 if (xorigin < 0) 222 xorigin += screendata_width; 223 else if (xorigin >= screendata_width) 224 xorigin -= screendata_width; 225 226 xsource = (xdisplay + xorigin) % screendata_width; 227 228 /* Plot a column in two pieces if the vertical origin is 229 non-zero. The first piece is at (xdisplay, 0) and 230 provides the lower part of the background image displaced 231 upwards (or downwards having wrapped around) on the 232 screen. */ 233 234 copy_display_section(&display_config, screendata, 235 screendata_width, screendata_height, 236 xsource, yorigin, 237 column_width, screendata_height - yorigin, 238 xdisplay, 0, 239 -1, 1); 240 241 /* The second column is at (xdisplay, h - yorigin) and 242 provides the upper part of the background image displaced 243 downwards (or upwards having wrapped around) on the 244 screen. */ 245 246 if (yorigin) 247 copy_display_section(&display_config, screendata, 248 screendata_width, screendata_height, 249 xsource, 0, 250 column_width, yorigin, 251 xdisplay, screendata_height - yorigin, 252 -1, 1); 253 } 254 } 255 256 /* Switch direction periodically. */ 257 258 i++; 259 if (i == 4) 260 i = 0; 261 } 262 } 263 } 264 265 /* Fill the screen with characters. */ 266 267 static void write_chars(void) 268 { 269 int x = 0, y = 0; 270 char c; 271 272 font_config.chars = (char_definition_t *) fontchars; 273 font_config.table = fonttable; 274 font_config.base = fontbase; 275 font_config.limit = fontlimit; 276 277 while (y < display_config.line_count) 278 for (c = (char) font_config.base; c < (char) font_config.limit; c++) 279 { 280 x = write_char(&display_config, &font_config, c, x, y, 0xff); 281 282 if (x > display_config.line_length) 283 { 284 x = 0; y += 9; 285 } 286 } 287 } 288 289 290 291 /* Main program. */ 292 293 void main(void) 294 { 295 init_memory(); 296 init_pins(); 297 init_outputs(); 298 299 unlock_config(); 300 config_oc(); 301 config_uart(); 302 lock_config(); 303 304 #ifndef TRANSFER_CPU 305 init_dma(); 306 #endif 307 308 #ifdef PARALLEL_MODE 309 init_pm(); 310 311 /* Configure parallel master mode. */ 312 313 pm_init(0, 0b10); 314 pm_set_output(0, 1, 0); 315 pm_on(0); 316 #endif 317 318 uart_init(1, FPB, 115200); 319 uart_on(1); 320 321 /* Initialise memory for a double-buffered display. */ 322 323 init_display(&display_config, framebuffer, LINE_LENGTH, LINE_COUNT, FRAME_COUNT); 324 325 /* Initialise VGA output with one or two line channels, configuring a line 326 timer and any transfer timer, with an initiating channel being introduced 327 if a transfer timer is specified. */ 328 329 init_vga_with_timers(&display_config, LINE_CHANNELS, LINE_TIMER, TRANSFER_TIMER); 330 331 /* Configure VGA output transfer to the output register, also configuring 332 output compare units for horizontal and vertical sync. */ 333 334 vga_configure_transfer(VGA_OUTPUT); 335 vga_configure_sync(1, 2); 336 337 interrupts_on(); 338 339 /* Plot the image centred on the screen. */ 340 341 copy_display(&display_config, screendata, screendata_width, screendata_height, 342 (display_config.line_length - screendata_width) / 2, 343 (display_config.line_count - screendata_height) / 2, -1, 1); 344 345 /* Write a sequence of characters. */ 346 347 write_chars(); 348 349 /* Move a sprite around on the screen with a delay between each movement. */ 350 351 animate(1 << 18); 352 } 353 354 355 356 /* Exception and interrupt handlers. */ 357 358 void exception_handler(void) 359 { 360 blink(1 << 22, PORTA, LED_PIN); 361 } 362 363 void interrupt_handler(void) 364 { 365 vga_interrupt_handler(); 366 } 367 368 369 370 /* Peripheral pin configuration. */ 371 372 void config_oc(void) 373 { 374 /* Map OC1. */ 375 376 REG(OC1_PIN) = 0b0101; 377 378 /* Map OC2. */ 379 380 REG(OC2_PIN) = 0b0101; 381 } 382 383 void config_uart(void) 384 { 385 /* Map U1RX to RPB13. */ 386 387 REG(U1RXR) = 0b0011; /* U1RXR<3:0> = 0011 (RPB13) */ 388 389 /* Map U1TX to RPB15. */ 390 391 REG(RPB15R) = 0b0001; /* RPB15R<3:0> = 0001 (U1TX) */ 392 393 /* Set RPB13 to input. */ 394 395 SET_REG(TRISB, 1 << 13); 396 }