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Diffstat (limited to 'examples/vga-leaf.cpp')
| -rw-r--r-- | examples/vga-leaf.cpp | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/examples/vga-leaf.cpp b/examples/vga-leaf.cpp new file mode 100644 index 0000000..5159956 --- /dev/null +++ b/examples/vga-leaf.cpp @@ -0,0 +1,244 @@ +/* + VGA Output + + Outputs a red and white leaf to VGA. It should run most VGA monitors + at 640x480, though it does not follow the timing spec very + carefully. Real twisted or shielded wires, proper grounding, and not + doing this on a breadboard are recommended (but it seems to work ok + without). + + SerialUSB and SysTick are disabled to get rid of the most frequently + occurring interrupts (which mess with timing). This means that you + have to use perpetual bootloader mode or the reset button to flash + new programs. + + How to wire this to a VGA port: + D6 via ~200ohms to VGA Red (1) + D7 via ~200ohms to VGA Green (2) + D8 via ~200ohms to VGA Blue (3) + D11 to VGA VSync (14) (swapped?) + D12 to VGA HSync (13) (swapped?) + GND to VGA Ground (5) + GND to VGA Sync Ground (10) + + See also: + - http://pinouts.ru/Video/VGA15_pinout.shtml + - http://www.epanorama.net/documents/pc/vga_timing.html + + Created 20 July 2010 + By Bryan Newbold for LeafLabs + This code is released with no strings attached. + */ + +// FIXME: generalize for Native and Mini + +#include <wirish/wirish.h> + +// Pinouts -- you also must change the GPIO macros below if you change +// these +#define VGA_R 6 // STM32: A8 +#define VGA_G 7 // STM32: A9 +#define VGA_B 8 // STM32: A10 +#define VGA_V 11 // STM32: A6 +#define VGA_H 12 // STM32: A7 + +// These low level (and STM32 specific) macros make GPIO writes much +// faster +#define ABSRR ((volatile uint32*)0x40010810) +#define ABRR ((volatile uint32*)0x40010814) + +#define RBIT 8 // (see pinouts) +#define GBIT 9 +#define BBIT 10 + +#define VGA_R_HIGH *ABSRR = BIT(RBIT) +#define VGA_R_LOW *ABRR = BIT(RBIT) +#define VGA_G_HIGH *ABSRR = BIT(GBIT) +#define VGA_G_LOW *ABRR = BIT(GBIT) +#define VGA_B_HIGH *ABSRR = BIT(BBIT) +#define VGA_B_LOW *ABRR = BIT(BBIT) + +#define ON_COLOR BIT(RBIT) +#define OFF_COLOR (BIT(RBIT) | BIT(GBIT) | BIT(BBIT)) + +// set has priority, so clear every bit and set some given bits: +#define VGA_COLOR(c) (*ABSRR = c | \ + BIT(RBIT+16) | BIT(GBIT+16) | BIT(BBIT+16)) + +#define VGA_V_HIGH *ABSRR = BIT(6) +#define VGA_V_LOW *ABRR = BIT(6) +#define VGA_H_HIGH *ABSRR = BIT(7) +#define VGA_H_LOW *ABRR = BIT(7) + +void isr_porch(void); +void isr_start(void); +void isr_stop(void); +void isr_update(void); + +uint16 x = 0; // X coordinate +uint16 y = 0; // Y coordinate +uint16 logo_y = 0; // Y coordinate, mapped into valid logo index (for speed) +bool v_active = true; // Are we in the image? + +const uint8 x_max = 16; +const uint8 y_max = 18; +uint32 logo[y_max][x_max] = { + {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,}, + {0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,}, + {0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,}, + {0,0,0,0,1,0,0,1,0,0,1,0,0,0,0,0,}, + {0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,0,}, + {0,0,1,0,0,0,0,1,0,0,0,0,1,0,0,0,}, + {0,0,1,0,0,1,0,1,0,1,0,0,1,0,0,0,}, + {0,1,0,0,0,0,1,1,1,0,0,0,0,1,0,0,}, + {0,1,0,1,0,0,0,1,0,0,0,1,0,1,0,0,}, + {1,0,0,0,1,0,0,1,0,0,1,0,0,0,1,0,}, + {1,0,0,0,0,1,0,1,0,1,0,0,0,0,1,0,}, + {1,0,0,0,0,0,1,1,1,0,0,0,0,0,1,0,}, + {0,1,0,0,0,0,0,1,0,0,0,0,0,1,0,0,}, + {0,0,1,1,0,0,0,1,0,0,0,1,1,0,0,0,}, + {0,0,0,0,1,1,1,0,1,1,1,0,0,0,0,0,}, + {0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,}, + {0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,}, + {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,}, }; + +HardwareTimer timer(4); + +void setup() { + // Setup our pins + pinMode(BOARD_LED_PIN, OUTPUT); + pinMode(VGA_R, OUTPUT); + pinMode(VGA_G, OUTPUT); + pinMode(VGA_B, OUTPUT); + pinMode(VGA_V, OUTPUT); + pinMode(VGA_H, OUTPUT); + digitalWrite(VGA_R, LOW); + digitalWrite(VGA_G, LOW); + digitalWrite(VGA_B, LOW); + digitalWrite(VGA_H, HIGH); + digitalWrite(VGA_V, HIGH); + + // Fill the logo array with color patterns corresponding to its + // truth value. Note that we could get more tricky here, since + // there are 3 bits of color. + for (int y = 0; y < y_max; y++) { + for (int x = 0; x < x_max; x++) { + logo[y][x] = logo[y][x] ? ON_COLOR : OFF_COLOR; + } + } + + // This gets rid of the majority of the interrupt artifacts; + // there's still a glitch for low values of y, but let's not worry + // about that. (Probably due to the hackish way vsync is done). + SerialUSB.end(); + systick_disable(); + + // Configure + timer.pause(); // while we configure + timer.setPrescaleFactor(1); // Full speed + timer.setMode(TIMER_CH1, TIMER_OUTPUT_COMPARE); + timer.setMode(TIMER_CH2, TIMER_OUTPUT_COMPARE); + timer.setMode(TIMER_CH3, TIMER_OUTPUT_COMPARE); + timer.setMode(TIMER_CH4, TIMER_OUTPUT_COMPARE); + timer.setOverflow(2287); // Total line time + + timer.setCompare(TIMER_CH1, 200); + timer.attachInterrupt(TIMER_CH1, isr_porch); + timer.setCompare(TIMER_CH2, 300); + timer.attachInterrupt(TIMER_CH2, isr_start); + timer.setCompare(TIMER_CH3, 2170); + timer.attachInterrupt(TIMER_CH3, isr_stop); + timer.setCompare(TIMER_CH4, 1); // Could be zero, I guess + timer.attachInterrupt(TIMER_CH4, isr_update); + + timer.setCount(0); // Ready... + timer.resume(); // Go! +} + +void loop() { + toggleLED(); + delay(100); + + // Everything happens in the interrupts! +} + +// This ISR will end horizontal sync for most of the image and +// setup the vertical sync for higher line counts +void isr_porch(void) { + VGA_H_HIGH; + y++; + logo_y = map(y, 0, 478, 0, y_max); + // Back to the top + if (y >= 523) { + y = 1; + logo_y = 0; + v_active = true; + return; + } + // Other vsync stuff below the image + if (y >= 492) { + VGA_V_HIGH; + return; + } + if (y >= 490) { + VGA_V_LOW; + return; + } + if (y >= 479) { + v_active = false; + return; + } +} + +// This is the main horizontal sweep +void isr_start(void) { + // Skip if we're not in the image at all + if (!v_active) { + return; + } + + // Start Red + VGA_R_LOW; + VGA_R_HIGH; + + // For each "pixel", go ON_COLOR or OFF_COLOR + for (x = 0; x < 16; x++) { + // setting the color several times is just an easy way to + // delay, so the image is wider. if you only do the following + // once, you'll be able to make the logo array bigger: + VGA_COLOR(logo[logo_y][x]); + VGA_COLOR(logo[logo_y][x]); + VGA_COLOR(logo[logo_y][x]); + VGA_COLOR(logo[logo_y][x]); + VGA_COLOR(logo[logo_y][x]); + VGA_COLOR(logo[logo_y][x]); + } +} + +// End of the horizontal line +void isr_stop(void) { + if (!v_active) { + return; + } + VGA_R_LOW; + VGA_G_LOW; + VGA_B_LOW; +} + +// Setup horizonal sync +void isr_update(void) { + VGA_H_LOW; +} + +__attribute__((constructor)) void premain() { + init(); +} + +int main(void) { + setup(); + + while (true) { + loop(); + } + return 0; +} |