Brought examples/ up to date; PIN_MAP bugfix for D24.

1 files changed, 134 insertions, 78 deletions

diff --git a/examples/vga-scope.cpp b/examples/vga-scope.cpp
index 0265f9c..9c6dca5 100644
--- a/examples/vga-scope.cpp
+++ b/examples/vga-scope.cpp
@@ -1,34 +1,90 @@
-// Low-level, non-wirish demonstration of VGA
-//
-// Connect a microphone or something less to ANALOG_PIN
+/*
+  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.
+ */
 
 #include "wirish.h"
+#include "systick.h"
+
+// FIXME generalize for Native and Mini
 
-#define LED_PIN 13
+#define LED_PIN     BOARD_LED_PIN
 #define ANALOG_PIN 18
-#define VGA_R 5 // B6
-#define VGA_G 6 // A8
-#define VGA_B 7 // A9
-#define VGA_V 11 // A6
-#define VGA_H 12 // A7
-#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)
+
+// 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()
-{
+void setup() {
     pinMode(LED_PIN, OUTPUT);
     pinMode(ANALOG_PIN, INPUT_ANALOG);
     digitalWrite(LED_PIN, 1);
@@ -38,104 +94,104 @@ void setup()
     pinMode(VGA_V, OUTPUT);
     pinMode(VGA_H, OUTPUT);
 
-    /* Send a message out USART2  */
+    // Send a message out USART2
     Serial2.begin(9600);
-    Serial2.println("Video time...");
+    Serial2.println("Time to kill the radio star...");
 
     // This gets rid of the majority of the interrupt artifacts;
-    // a SysTick.end() is required as well
+    // 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_set_prescaler(4,0);
-    timer_set_mode(4, 1, TIMER_OUTPUTCOMPARE);
-    timer_set_mode(4, 2, TIMER_OUTPUTCOMPARE);
-    timer_set_mode(4, 3, TIMER_OUTPUTCOMPARE);
-    timer_set_mode(4, 4, TIMER_OUTPUTCOMPARE);
-    timer_set_reload(4, 2287);
-    timer_set_compare_value(4,1,200);
-    timer_set_compare_value(4,2,300);
-    timer_set_compare_value(4,3,2170);  // 2219 max...
-    timer_set_compare_value(4,4,1);
-    timer_attach_interrupt(4,1,isr_porch);
-    timer_attach_interrupt(4,2,isr_start);
-    timer_attach_interrupt(4,3,isr_stop);
-    timer_attach_interrupt(4,4,isr_update);
-
-    timer_set_count(4,0);
+    digitalWrite(VGA_H, 1);
+    digitalWrite(VGA_V, 1);
+
+    timer_pause(TIMER4);
+    timer_set_prescaler(TIMER4, 0);
+    timer_set_mode(TIMER4, 1, TIMER_OUTPUTCOMPARE);
+    timer_set_mode(TIMER4, 2, TIMER_OUTPUTCOMPARE);
+    timer_set_mode(TIMER4, 3, TIMER_OUTPUTCOMPARE);
+    timer_set_mode(TIMER4, 4, TIMER_OUTPUTCOMPARE);
+    timer_set_reload(TIMER4, 2287);
+    timer_set_compare_value(TIMER4, 1, 200);
+    timer_set_compare_value(TIMER4, 2, 250);
+    timer_set_compare_value(TIMER4, 3, 2170);  // 2219 max...
+    timer_set_compare_value(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);
 }
 
-int toggle = 0;
-uint16  x = 0;
 uint16 y = 0;
 uint16 val = 0;
-uint8 v_active = 1;
-GPIO_Port *portb = GPIOB_BASE;
+bool v_active = true;
+const uint16 x_max = 60;        // empirically (and lazily) determined
 
 void isr_porch(void) {
     VGA_H_HIGH;
     y++;
-    if(y>=523) {
-        y=1;
-        v_active = 1;
+    val = map(analogRead(ANALOG_PIN), 0, 4095, 0, x_max);
+    if(y >= 523) {
+        y = 1;
+        v_active = true;
         return;
     }
-    if(y>=492) {
+    if(y >= 492) {
         VGA_V_HIGH;
         return;
     }
-    if(y>=490) {
+    if(y >= 490) {
         VGA_V_LOW;
         return;
     }
-    if(y>=479) {    // 479
-        v_active = 0;
+    if(y >= 479) {
+        v_active = false;
         return;
     }
 
 }
 
 void isr_start(void) {
-    if(!v_active) { return; }
-    VGA_R_HIGH;
-    VGA_R_HIGH;
-    VGA_R_HIGH;
-    VGA_R_LOW;
-    //delayMicroseconds(2);
-    //gpio_write_bit(GPIOA_BASE, 8, 1); // VGA_G
-    for(x=0; x<(val>>6); x++) {
-        }
-    VGA_B_HIGH;
-    VGA_G_HIGH;
-    VGA_G_LOW;
-    VGA_B_LOW;
-    //VGA_R_HIGH;
-    //val = (val + analogRead(ANALOG_PIN))/2;
-    val = analogRead(ANALOG_PIN);
-
+    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_R_LOW;
-    VGA_G_LOW;
-    VGA_B_LOW;
+    if (!v_active) {
+        return;
+    }
+    VGA_COLOR(COLOR_BLACK);
 }
+
 void isr_update(void) {
     VGA_H_LOW;
 }
 
 void loop() {
-    //val = analogRead(ANALOG_PIN);
+    toggleLED();
+    delay(100);
 }
 
+__attribute__((constructor)) void premain() {
+    init();
+}
 
 int main(void) {
-    init();
     setup();
 
     while (1) {