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-rw-r--r--examples/vga-leaf.cpp201
1 files changed, 120 insertions, 81 deletions
diff --git a/examples/vga-leaf.cpp b/examples/vga-leaf.cpp
index d1c6d7d..f31dc87 100644
--- a/examples/vga-leaf.cpp
+++ b/examples/vga-leaf.cpp
@@ -1,21 +1,21 @@
/*
- Crude VGA Output
+ VGA Output
- Outputs a red and white leaf to VGA. This implementation is crude and noisy,
- but a fun demo. 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).
+ 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 is disabled to get rid of most interrupts (which mess with timing);
- the SysTick is probably the source of the remaining flickers. This means that
- you have to use perpetual bootloader or the reset button to flash new
- programs.
+ 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:
- D5 via ~200ohms to VGA Red (1)
- D6 via ~200ohms to VGA Green (2)
- D7 via ~200ohms to VGA Blue (3)
+ 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)
@@ -24,48 +24,65 @@
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.
-
*/
-#include "wirish.h"
+// FIXME: generalize for Native and Mini
-#define LED_PIN 13
+#include "wirish.h"
-// Pinouts
-#define VGA_R 5 // STM32: B6
-#define VGA_G 6 // STM32: A8
-#define VGA_B 7 // STM32: A9
+// 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 macros make GPIO writes much faster
-#define VGA_R_HIGH (GPIOB_BASE)->BSRR = BIT(6)
-#define VGA_R_LOW (GPIOB_BASE)->BRR = BIT(6)
-#define VGA_G_HIGH (GPIOA_BASE)->BSRR = BIT(8)
-#define VGA_G_LOW (GPIOA_BASE)->BRR = BIT(8)
-#define VGA_B_HIGH (GPIOA_BASE)->BSRR = BIT(9)
-#define VGA_B_LOW (GPIOA_BASE)->BRR = BIT(9)
-#define VGA_V_HIGH (GPIOA_BASE)->BSRR = BIT(6)
-#define VGA_V_LOW (GPIOA_BASE)->BRR = BIT(6)
-#define VGA_H_HIGH (GPIOA_BASE)->BSRR = BIT(7)
-#define VGA_H_LOW (GPIOA_BASE)->BRR = BIT(7)
+// 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);
-uint8 toggle;
uint16 x = 0; // X coordinate
uint16 y = 0; // Y coordinate
-uint8 v_active = 1; // Are we in the image?
+uint16 logo_y = 0; // Y coordinate, mapped into valid logo index (for speed)
+bool v_active = true; // Are we in the image?
-// 1-bit!
-uint8 logo[18][16] = {
+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,},
@@ -85,9 +102,11 @@ uint8 logo[18][16] = {
{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(LED_PIN, OUTPUT);
+ pinMode(BOARD_LED_PIN, OUTPUT);
pinMode(VGA_R, OUTPUT);
pinMode(VGA_G, OUTPUT);
pinMode(VGA_B, OUTPUT);
@@ -99,91 +118,108 @@ void setup() {
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();
- SystemTick.end();
+ systick_disable();
// Configure
- Timer4.pause(); // while we configure
- Timer4.setPrescaleFactor(1); // Full speed
- Timer4.setChannel1Mode(TIMER_OUTPUTCOMPARE);
- Timer4.setChannel2Mode(TIMER_OUTPUTCOMPARE);
- Timer4.setChannel3Mode(TIMER_OUTPUTCOMPARE);
- Timer4.setChannel4Mode(TIMER_OUTPUTCOMPARE);
- Timer4.setOverflow(2287); // Total line time
-
- Timer4.setCompare1(200);
- Timer4.attachCompare1Interrupt(isr_porch);
- Timer4.setCompare2(300);
- Timer4.attachCompare2Interrupt(isr_start);
- Timer4.setCompare3(2170);
- Timer4.attachCompare3Interrupt(isr_stop);
- Timer4.setCompare4(1); // Could be zero I guess
- Timer4.attachCompare4Interrupt(isr_update);
-
- Timer4.setCount(0); // Ready...
- Timer4.resume(); // Go!
+ 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() {
- toggle ^= 1;
- digitalWrite(LED_PIN, toggle);
+ 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;
- v_active = 1;
+ if (y >= 523) {
+ y = 1;
+ logo_y = 0;
+ v_active = true;
return;
}
// Other vsync stuff below the image
- if(y>=492) {
+ if (y >= 492) {
VGA_V_HIGH;
return;
}
- if(y>=490) {
+ if (y >= 490) {
VGA_V_LOW;
return;
}
- if(y>=479) {
- v_active = 0;
+ if (y >= 479) {
+ v_active = false;
return;
}
}
// This is the main horizontal sweep
-void isr_start(void) {
+void isr_start(void) {
// Skip if we're not in the image at all
- if(!v_active) { return; }
+ if (!v_active) {
+ return;
+ }
// Start Red
VGA_R_LOW;
VGA_R_HIGH;
- // For each "pixel" (really 20 or so screen pixels?) go red or white
- for(x=0; x<32; x++) {
- if(logo[y/28][x/2]) {
- VGA_G_HIGH;
- VGA_B_HIGH;
- } else {
- VGA_G_LOW;
- VGA_B_LOW;
- }
+ // 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; }
+ if (!v_active) {
+ return;
+ }
VGA_R_LOW;
VGA_G_LOW;
VGA_B_LOW;
@@ -194,11 +230,14 @@ void isr_update(void) {
VGA_H_LOW;
}
-int main(void) {
+__attribute__((constructor)) void premain() {
init();
+}
+
+int main(void) {
setup();
- while (1) {
+ while (true) {
loop();
}
return 0;
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