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 "main.h" 28 #include "devconfig.h" 29 #include "vga.h" 30 #include "display.h" 31 #include "display_config.h" 32 #include "vga_display.h" 33 34 35 36 /* Define timers if not indicated in the build configuration. */ 37 38 #ifndef LINE_CHANNELS 39 #define LINE_CHANNELS 1 40 #endif 41 42 #ifndef LINE_TIMER 43 #define LINE_TIMER 2 44 #endif 45 46 #ifndef TRANSFER_TIMER 47 #define TRANSFER_TIMER 0 48 #endif 49 50 /* Define different output ports and pins for parallel mode. */ 51 52 #ifndef PARALLEL_MODE 53 #define VGA_OUTPUT PORTB 54 #define OC1_PIN RPA0R 55 #define OC2_PIN RPA1R 56 #define LED_PIN (1 << 3) 57 #else 58 #define VGA_OUTPUT PM_REG(0, PMxDIN) 59 #define OC1_PIN RPB4R 60 #define OC2_PIN RPB5R 61 #define LED_PIN (1 << 2) 62 #endif 63 64 65 66 /* Bundled image data. */ 67 68 extern uint8_t screendata[]; 69 extern uint32_t screendata_width, screendata_height; 70 71 72 73 /* Blink an attached LED with delays implemented using a loop. */ 74 75 static void blink(uint32_t delay, uint32_t port, uint32_t pins) 76 { 77 uint32_t counter; 78 79 /* Clear outputs (LED). */ 80 81 CLR_REG(port, pins); 82 83 while (1) 84 { 85 counter = delay; 86 87 while (counter--) __asm__(""); /* retain loop */ 88 89 /* Invert outputs (LED). */ 90 91 INV_REG(port, pins); 92 } 93 } 94 95 96 97 /* Main program. */ 98 99 void main(void) 100 { 101 init_memory(); 102 init_pins(); 103 init_outputs(); 104 105 unlock_config(); 106 config_oc(); 107 config_uart(); 108 lock_config(); 109 110 init_dma(); 111 112 #ifdef PARALLEL_MODE 113 init_pm(); 114 115 /* Configure parallel master mode. */ 116 117 pm_init(0, 0b10); 118 pm_set_output(0, 1, 0); 119 pm_on(0); 120 #endif 121 122 /* Initialise VGA output with one or two line channels, configuring a line 123 timer and any transfer timer, with an initiating channel being introduced 124 if a transfer timer is specified. */ 125 126 init_vga_with_timers(&display_config, LINE_CHANNELS, LINE_TIMER, TRANSFER_TIMER); 127 128 /* Configure VGA output transfer to the output register, also configuring 129 output compare units for horizontal and vertical sync. */ 130 131 vga_configure_transfer(VGA_OUTPUT); 132 vga_configure_sync(1, 2); 133 134 uart_init(1, FPB, 115200); 135 uart_on(1); 136 137 interrupts_on(); 138 139 copy_to_framebuffer(&display_config, screendata, screendata_width, screendata_height); 140 blink(1 << 24, PORTA, LED_PIN); 141 } 142 143 144 145 /* Exception and interrupt handlers. */ 146 147 void exception_handler(void) 148 { 149 blink(3 << 12, PORTA, LED_PIN); 150 } 151 152 void interrupt_handler(void) 153 { 154 uint32_t ifs; 155 156 /* Check for a OC1 interrupt condition. */ 157 158 ifs = REG(OCIFS) & OC_INT_FLAGS(1, OCxIF); 159 160 if (ifs) 161 { 162 vga_interrupt_handler(); 163 CLR_REG(OCIFS, ifs); 164 } 165 } 166 167 168 169 /* Peripheral pin configuration. */ 170 171 void config_oc(void) 172 { 173 /* Map OC1. */ 174 175 REG(OC1_PIN) = 0b0101; 176 177 /* Map OC2. */ 178 179 REG(OC2_PIN) = 0b0101; 180 } 181 182 void config_uart(void) 183 { 184 /* Map U1RX to RPB13. */ 185 186 REG(U1RXR) = 0b0011; /* U1RXR<3:0> = 0011 (RPB13) */ 187 188 /* Map U1TX to RPB15. */ 189 190 REG(RPB15R) = 0b0001; /* RPB15R<3:0> = 0001 (U1TX) */ 191 192 /* Set RPB13 to input. */ 193 194 SET_REG(TRISB, 1 << 13); 195 }