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Diffstat (limited to 'examples/vga-scope.cpp')
| -rw-r--r-- | examples/vga-scope.cpp | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/examples/vga-scope.cpp b/examples/vga-scope.cpp new file mode 100644 index 0000000..8730cf0 --- /dev/null +++ b/examples/vga-scope.cpp @@ -0,0 +1,205 @@ +/* + VGA Oscilloscope demo. + + Connect a microphone or something like it to ANALOG_PIN (0V -- 3.3V + only; 0.2V -- 3.1V will probably look nicer); an attached VGA + monitor will display the signal roughly in real-time. + + The thick blue line corresponds roughly to 0V. + + This is a fairy crude hack, but it's fun to watch/toy around with. + + 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 + + This code is released into the public domain. + + Authors: + + Bryan Newbold <bnewbold@leaflabs.com> + Marti Bolivar <mbolivar@leaflabs.com> + */ + +#include <wirish/wirish.h> +#include <libmaple/systick.h> + +// FIXME: generalize for Native and Mini + +#define ANALOG_PIN 18 + +// 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 COLOR_WHITE (BIT(RBIT) | BIT(GBIT) | BIT(BBIT)) +#define COLOR_BLACK 0 +#define COLOR_RED BIT(RBIT) +#define COLOR_GREEN BIT(GBIT) +#define COLOR_BLUE BIT(BBIT) + +#define BORDER_COLOR COLOR_BLUE + +// 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); + +void setup() { + pinMode(BOARD_LED_PIN, OUTPUT); + pinMode(ANALOG_PIN, INPUT_ANALOG); + digitalWrite(BOARD_LED_PIN, 1); + pinMode(VGA_R, OUTPUT); + pinMode(VGA_G, OUTPUT); + pinMode(VGA_B, OUTPUT); + pinMode(VGA_V, OUTPUT); + pinMode(VGA_H, OUTPUT); + + // Send a message out USART2 + Serial2.begin(9600); + Serial2.println("Time to kill the radio star..."); + + // 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(); + + digitalWrite(VGA_R, 0); + digitalWrite(VGA_G, 0); + digitalWrite(VGA_B, 0); + digitalWrite(VGA_H, 1); + digitalWrite(VGA_V, 1); + + timer_pause(TIMER4); + timer_set_prescaler(TIMER4, 0); + timer_set_mode(TIMER4, 1, TIMER_OUTPUT_COMPARE); + timer_set_mode(TIMER4, 2, TIMER_OUTPUT_COMPARE); + timer_set_mode(TIMER4, 3, TIMER_OUTPUT_COMPARE); + timer_set_mode(TIMER4, 4, TIMER_OUTPUT_COMPARE); + timer_set_reload(TIMER4, 2287); + timer_set_compare(TIMER4, 1, 200); + timer_set_compare(TIMER4, 2, 250); + timer_set_compare(TIMER4, 3, 2170); // 2219 max... + timer_set_compare(TIMER4, 4, 1); + timer_attach_interrupt(TIMER4, 1, isr_porch); + timer_attach_interrupt(TIMER4, 2, isr_start); + timer_attach_interrupt(TIMER4, 3, isr_stop); + timer_attach_interrupt(TIMER4, 4, isr_update); + + timer_set_count(TIMER4, 0); + timer_resume(TIMER4); +} + +uint16 y = 0; +uint16 val = 0; +bool v_active = true; +const uint16 x_max = 60; // empirically (and sloppily) determined + +void isr_porch(void) { + VGA_H_HIGH; + y++; + val = map(analogRead(ANALOG_PIN), 0, 4095, 0, x_max); + if (y >= 523) { + y = 1; + v_active = true; + return; + } + if (y >= 492) { + VGA_V_HIGH; + return; + } + if (y >= 490) { + VGA_V_LOW; + return; + } + if (y >= 479) { + v_active = false; + return; + } + +} + +void isr_start(void) { + if (!v_active) { + return; + } + VGA_COLOR(BORDER_COLOR); + for (int x = 0; x < val; x++) { + VGA_COLOR(COLOR_BLACK); + } + VGA_COLOR(COLOR_WHITE); + VGA_COLOR(COLOR_BLACK); +} + +void isr_stop(void) { + if (!v_active) { + return; + } + VGA_COLOR(COLOR_BLACK); +} + +void isr_update(void) { + VGA_H_LOW; +} + +void loop() { + toggleLED(); + delay(100); +} + +__attribute__((constructor)) void premain() { + init(); +} + +int main(void) { + setup(); + + while (true) { + loop(); + } + return 0; +} |