scanner head stuff

sketch

#include <Arduino.h>
#include <ports.h>
#include <base.h>
#include <DirectIO.h>

#include <Adafruit_NeoPixel.h>
#include <TimerOne.h>

#define CLKPIN TIMER1_A_PIN
#define TRGPIN 4
#define DEBUGPIN 6
#define FIRSTFIELD 7

#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif 

Output<TRGPIN> trg;
Output<CLKPIN> clk;
Output<6> dbg;
Output<FIRSTFIELD> ff;

#define NUMPIXELS 8
#define NEO_PIN 8
Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, NEO_PIN, NEO_RGB + NEO_KHZ800);

const uint8_t PROGMEM gamma8[] = {
    0,  0,  0,  0,  0,  0,  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,  1,
    1,  1,  1,  1,  1,  1,  1,  1,  1,  2,  2,  2,  2,  2,  2,  2,
    2,  3,  3,  3,  3,  3,  3,  3,  4,  4,  4,  4,  4,  5,  5,  5,
    5,  6,  6,  6,  6,  7,  7,  7,  7,  8,  8,  8,  9,  9,  9, 10,
   10, 10, 11, 11, 11, 12, 12, 13, 13, 13, 14, 14, 15, 15, 16, 16,
   17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 23, 24, 24, 25,
   25, 26, 27, 27, 28, 29, 29, 30, 31, 32, 32, 33, 34, 35, 35, 36,
   37, 38, 39, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 50,
   51, 52, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68,
   69, 70, 72, 73, 74, 75, 77, 78, 79, 81, 82, 83, 85, 86, 87, 89,
   90, 92, 93, 95, 96, 98, 99,101,102,104,105,107,109,110,112,114,
  115,117,119,120,122,124,126,127,129,131,133,135,137,138,140,142,
  144,146,148,150,152,154,156,158,160,162,164,167,169,171,173,175,
  177,180,182,184,186,189,191,193,196,198,200,203,205,208,210,213,
  215,218,220,223,225,228,231,233,236,239,241,244,247,249,252,255 };

void setup() {
  analogReference(EXTERNAL);
  pinMode(CLKPIN, OUTPUT);
  //pinMode(DEBUGPIN, OUTPUT);

  Timer1.initialize(1); // ~1mhz
  Timer1.pwm(CLKPIN, 512); // 50% duty cycle
  Timer1.stop();
  pinMode(TRGPIN, OUTPUT);
  pinMode(A0, INPUT);
  pinMode(ledToPin(0), OUTPUT);
  pinMode(ledToPin(1), OUTPUT);
  pinMode(ledToPin(2), OUTPUT);
  Serial.begin(115200);
  cbi(ADCSRA, ADPS0);
  cbi(ADCSRA, ADPS1);
  cbi(ADCSRA, ADPS2);
  sbi(ADCSRA, ADPS1);

//  Serial.print("prescaler = ");
//  Serial.println(ADCSRA & 0xE0);
  pixels.begin();
}

int avgRead(int port, int samples)
{
  int i;
  long reading = 0;
  for(i = 0; i < samples; i++)
  {
    reading += analogRead(port);
  }

  reading /= samples;

  return reading;
}

void clockCycle(int pin, int count)
{
  while(count--)
  {
    digitalWrite(pin, HIGH);
    digitalWrite(pin, LOW);
  }
}

int ledToPin(int color)
{
  switch(color)
  {
    case 0: // red
      return 2;
      break;
      
    case 1: // green
      return 3;
      break;
      
    case 2: // blue
      return 5;
      break;
  }
}
void ledOn(int color)
{
  digitalWrite(ledToPin(color), LOW);
}

void ledOff(int color)
{
  digitalWrite(ledToPin(color), HIGH);
}

void ledsOn()
{
  for(int i = 0; i <= 2; i++)
    ledOn(i);
}

void ledsOff()
{
  for(int i = 0; i <= 2; i++)
    ledOff(i);
}

// returns n samples from start of readback to end of readback
void readLine(byte* output, int samples)
{
  int zeroLevel;
  int blackLevel;
  int clocks;
  int i;

  int samplePos = 2593 / samples;
  int currSample = 0;
  
  shiftOut(TRGPIN, CLKPIN, MSBFIRST, 0xF0); // trigger pulse and slow clock

  // lock step through front porch with slow clock in order to capture reference levels without unpredictable jitter
  clockCycle(CLKPIN, 4);

  // sample black level
  for(i=0; i < 3; i++)
  {
    clocks=5; while(clocks--)
    {
      clk=1;
      clk=0;
    }
    blackLevel += avgRead(A0, 3);
  }

  blackLevel /= 3;
//  Serial.print("blackLevel = ");
//  Serial.println(blackLevel);

  // 65 more clock cycles until analog goodies
  clocks = 65; while(clocks--)
  {
    clk=1;
    clk=0;
  }

  #define ANALOG_CLOCKS (12 * 216 + 1)

  int stepSpacing = ANALOG_CLOCKS / samples;
  int nextSample = 0;

  // go through analog bins
  for(i = 0; i < 12 * 216 + 1; i++)
  {
    clk = 1;

    if(nextSample-- == 0)
    {
      dbg=1;
      nextSample = stepSpacing;
//      output[currSample++] = map(avgRead(A0, 5), blackLevel, 1024, 0, 255);
      output[currSample++] = map(analogRead(A0), blackLevel, 1024, 0, 255);
      dbg=0;
    }
    clk = 0;
  }

#if 0
  for(i = 0; i < 2593; i++)
  {
    clk =1;
    clk =0;
  }
  #endif

}

void loop() {
  int led = 0;
  byte samples[64];
  byte redSamples[NUMPIXELS];
  byte greenSamples[NUMPIXELS];
  byte blueSamples[NUMPIXELS];
  int i;

  ff=1;
  ff=0;

#if 1
  ledOn(0);
  readLine(redSamples, NUMPIXELS);
  ledsOff();

  ledOn(1);
  readLine(greenSamples, NUMPIXELS);
  ledsOff();

  ledOn(2);
  readLine(blueSamples, NUMPIXELS);
  ledsOff();
#endif  
  #if 0
  for(led = 0; led < 0; led++){
    ledOn(led);
    readLine(samples, 4);
    ledOff(led);
  }
  ledsOff();

  #endif

  for(i = 0; i < NUMPIXELS; i++)
  {
    #if 0
    Serial.print("sample[");
    Serial.print(i);
    Serial.println("] = ");
    Serial.print("red ");
    Serial.println(redSamples[i]);
    Serial.print("green ");
    Serial.println(greenSamples[i]);
    Serial.print("blue ");
    Serial.println(blueSamples[i]);
    #endif


  pixels.setPixelColor(i, pixels.Color(pgm_read_byte(&gamma8[greenSamples[i]]), pgm_read_byte(&gamma8[redSamples[i]]), pgm_read_byte(&gamma8[blueSamples[i]])));

//    pixels.setPixelColor(i, pixels.Color(0, 0, 0));
//    pixels.setPixelColor(i, pixels.Color(redSamples[i], greenSamples[i], blueSamples[i]));
//  pixels.setPixelColor(i, pixels.Color(pgm_read_byte(&gamma8[redSamples[i]]), pgm_read_byte(&gamma8[greenSamples[i]]), pgm_read_byte(&gamma8[blueSamples[i]])));
//    pixels.setPixelColor(i, pixels.Color(pgm_read_byte(&gamma8[redSamples[i]]), pgm_read_byte(&gamma8[redSamples[i]]), pgm_read_byte(&gamma8[redSamples[i]])));

    pixels.show(); // This sends the updated pixel color to the hardware.

    
  }
//  delay(100);
  //delayMicroseconds(100);
}

void old_loop() {
  int bin;
  int i;
  int samples[12];
  int clocks;
  int zeroLevel;
  int blackLevel;
 static  int led=0;
  //shiftOut(TRGPIN, CLKPIN, MSBFIRST, 0);
  dbg=1;
  zeroLevel = avgRead(A0, 5);
//  zeroLevel = analogRead(A0);
  dbg=0;

dbg=1;
  shiftOut(TRGPIN, CLKPIN, MSBFIRST, 0xF0); // trigger pulse and slow clock
  dbg=0;

  // lock step through front porch with slow clock in order to capture reference levels without unpredictable jitter
  dbg=1;
  clockCycle(CLKPIN, 4);
  dbg=0;

dbg=1;
  for(i=0; i < 3; i++)
  {
    clocks=5; while(clocks--)
    {
      clk=1;
      clk=0;
    }
    blackLevel += avgRead(A0, 3);
  }

  blackLevel /= 4;
//    Serial.print("blackLevel = ");
//    Serial.println(blackLevel);
  dbg=0;

if(led == 0){
  ff = 1;
  ff = 0;
}
  ledOn(led);
//ledsOn();
  dbg=1;
  clocks = 40; while(clocks--)
  {
    clk=1;
    clk=0;
  }
  dbg=0;

  for(i = 0; i < 350*8; i++)
    {
      clk =1;
      clk =0;
    }
    dbg =1;

    dbg=0;
//  Timer1.pwm(CLKPIN, 512); // fast clock
/*  dbg=1;
  for(i = 0; i < 300; i++)
  {
    samples[i] = analogRead(A0);
    //delayMicroseconds(2000);
  }
  dbg=0;
*/
  // sample front porch reference level 2 clocks later, for 80 hs clocks
  // sample bins 83 clocks after fast start
  // bins seem to be 215 clocks wide, 12 bins, 1 clock per pixel

  //delayMicroseconds(1);
#if 0
  dbg=1;
  noInterrupts();
  while(analogRead(A0) -5 < zeroLevel)
    ;
  interrupts();
  // wait for voltage to increase to follow clock jitter
  dbg=0;
#endif


  dbg = 1;
 blackLevel = avgRead(A0, 5);
//  blackLevel = analogRead(A0);
  dbg = 0;

#if 0
noInterrupts();
  while(analogRead(A0) -10< blackLevel)
{
  dbg=1;
  delayMicroseconds(0);
  dbg=0;
}
    ;
interrupts();

#endif

  dbg = 1;
  delayMicroseconds(1);
  dbg = 0;
/*
  delayMicroseconds(100);
  dbg=1;
  bin= analogRead(A0);
  dbg=0;
  */

//  delayMicroseconds(2670);
  Timer1.stop();
  digitalWrite(CLKPIN, LOW);
  /*
    Serial.print("zeroLevel = ");
  Serial.println(zeroLevel);

  Serial.print("blackLevel = ");
  Serial.println(blackLevel);
/*  Serial.print("bin = ");
  Serial.println(bin);
  */

//delay(50);
#if 1
  ledOff(led);
  // switch LED
  if(++led > 2)
    led = 0;
#endif
//ledsOff();

//    Serial.println(led);
//  Serial.print("normalized = ");
 // Serial.println(map(bin - blackLevel, zeroLevel, 1024, 0, 255));
  //delay(10); // inter line delay
  delayMicroseconds(100);
}

what

the scan head expects a trigger, then a clock, analog values come out on one of the pins during the clocking

the first few elements are from dark elements so you can use them as a reference

sketch reads the 3 full color fields and renders them on a ws2812b strip

these are supposed to be in close contact with paper or something, but it works ok to about 4 inches (can resolve space between fingers)