Initial commit : 1 electrode

main.py

@@ -0,0 +1,45 @@
+#!/bin/env python
+
+import serial
+import pygame
+
+ser = serial.Serial("/dev/ttyACM0", 115200)
+pygame.init()
+
+size = width, height = 640, 480
+black = 0, 0, 0
+screen = pygame.display.set_mode(size)
+background = pygame.Surface(screen.get_size())
+background = background.convert()
+background.fill(black)
+
+try:
+    ser.open()
+except Exception, e:
+    print("Error while opening serial port : "+str(e))
+
+if ser.isOpen():
+    ser.flushInput()
+    ser.flushOutput()
+
+    maximum = -1.
+    minimum = -1.
+    print("Calibration")
+    screen.blit(background, (0,0))
+    pygame.display.flip()
+    for i in range(50) :
+        line = float(ser.readline())
+	
+	if line < minimum or minimum < 0:
+		minimum = line
+	if line > maximum:
+		maximum = line
+
+    print("Go")
+    while True:
+	line = float(ser.readline())
+	background.fill((int(255.*(line-minimum)/(maximum-minimum)), 0, 0))
+	screen.blit(background, (0,0))
+	pygame.display.flip()
+
+    ser.close()

touchless_tracking/touchless_tracking.ino

@@ -0,0 +1,58 @@
+#define resolution 8
+#define mains 50 // 60: north america, japan; 50: most other places
+
+#define refresh 2 * 1000000 / mains
+
+// Counter for the timer
+extern volatile unsigned long timer0_overflow_count;
+
+/* === */
+/* ??? */
+void startTimer() {
+    timer0_overflow_count = 0;
+    TCNT0 = 0;
+}
+
+unsigned long checkTimer() {
+    return ((timer0_overflow_count << 8) + TCNT0) << 2;
+}
+
+long time(int pin, byte mask) {
+    unsigned long count = 0, total = 0;
+    
+    while(checkTimer() < refresh) {
+        // pinMode is about 6 times slower than assigning
+        // DDRB directly, but that pause is important
+        pinMode(pin, OUTPUT);
+        PORTB = 0;
+        
+        pinMode(pin, INPUT);
+        
+        while((PINB & mask) == 0)
+            count++;
+            
+        total++;
+    }
+    startTimer();
+    return (count << resolution) / total;
+}
+
+/* ??? */
+/* === */
+
+void setup() {
+    // Initialize serial communication
+    Serial.begin(115200);
+    
+    // INPUT on pin 8
+    pinMode(8, INPUT);
+    
+    // Start timer
+    startTimer();
+}
+
+void loop() {
+    // Print output to serial in decimal
+    Serial.print(time(8, B00000001), DEC);
+    Serial.print(" ");
+}