Markus Kalkbrenner / Mbed 2 deprecated Pinscape_Controller

work in progress

Dependencies:   FastAnalogIn FastIO USBDevice mbed FastPWM SimpleDMA

Fork of Pinscape_Controller by Mike R

ccdSensor.h@18:5e890ebd0023, 2015-02-27 (annotated)

Committer:
mjr
Date:
Fri Feb 27 07:41:29 2015 +0000
Revision:
18:5e890ebd0023
Parent:
17:ab3cec0c8bf4
Child:
25:e22b88bd783a
Old debounce about to be removed

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mjr 17:ab3cec0c8bf4 1 // CCD plunger sensor
mjr 17:ab3cec0c8bf4 2 //
mjr 17:ab3cec0c8bf4 3 // This file implements our generic plunger sensor interface for the
mjr 17:ab3cec0c8bf4 4 // TAOS TSL1410R CCD array sensor.
mjr 17:ab3cec0c8bf4 5
mjr 17:ab3cec0c8bf4 6
mjr 17:ab3cec0c8bf4 7
mjr 17:ab3cec0c8bf4 8 // Number of pixels we read from the CCD on each frame. This can be
mjr 17:ab3cec0c8bf4 9 // less than the actual sensor size if desired; if so, we'll read every
mjr 17:ab3cec0c8bf4 10 // nth pixel. E.g., with a 1280-pixel physical sensor, if npix is 320,
mjr 17:ab3cec0c8bf4 11 // we'll read every 4th pixel. Reading a pixel is fairly time-consuming,
mjr 17:ab3cec0c8bf4 12 // because it requires waiting for the pixel's electric charge to
mjr 17:ab3cec0c8bf4 13 // stabilize on the CCD output, for the charge to transfer to the KL25Z
mjr 17:ab3cec0c8bf4 14 // input, and then for the KL25Z analog voltage sampler to get a stable
mjr 17:ab3cec0c8bf4 15 // reading. This all takes about 15us per pixel, which adds up to
mjr 17:ab3cec0c8bf4 16 // a relatively long time in such a large array. However, we can skip
mjr 17:ab3cec0c8bf4 17 // a pixel without waiting for all of that charge stabilization time,
mjr 17:ab3cec0c8bf4 18 // so we can get higher frame rates by only sampling a subset of the
mjr 17:ab3cec0c8bf4 19 // pixels. The array is so dense (400dpi) that we can still get
mjr 17:ab3cec0c8bf4 20 // excellent resolution by reading a fraction of the total pixels.
mjr 17:ab3cec0c8bf4 21 //
mjr 17:ab3cec0c8bf4 22 // Empirically, 160 pixels seems to be the point of diminishing returns
mjr 17:ab3cec0c8bf4 23 // for resolution - going higher will only improve the apparent smoothness
mjr 17:ab3cec0c8bf4 24 // slightly, if at all. 160 pixels gives us 50dpi on the sensor, which
mjr 17:ab3cec0c8bf4 25 // is roughly the same as the physical pixel pitch of a typical cabinet
mjr 17:ab3cec0c8bf4 26 // playfield monitor. (1080p HDTV displayed 1920x1080 pixels, and a 40"
mjr 17:ab3cec0c8bf4 27 // TV is about 35" wide, so the dot pitch is about 55dpi across the width
mjr 17:ab3cec0c8bf4 28 // of the TV. If on-screen plunger is displayed at roughly the true
mjr 17:ab3cec0c8bf4 29 // physical size, it's about 3" on the screen, or about 165 pixels. So at
mjr 17:ab3cec0c8bf4 30 // 160 pixels on the sensor, one pixel on the sensor translates to almost
mjr 17:ab3cec0c8bf4 31 // exactly one on-screen pixel on the TV, which makes the animated motion
mjr 17:ab3cec0c8bf4 32 // on-screen about as smooth as it can be. Looked at another way, 50dpi
mjr 17:ab3cec0c8bf4 33 // means that we're measuring the physical shooter rod position in about
mjr 17:ab3cec0c8bf4 34 // half-millimeter increments, which is probably better than I can
mjr 17:ab3cec0c8bf4 35 // discern by feel or sight.
mjr 17:ab3cec0c8bf4 36 const int npix = 160;
mjr 17:ab3cec0c8bf4 37
mjr 17:ab3cec0c8bf4 38
mjr 17:ab3cec0c8bf4 39 class PlungerSensor
mjr 17:ab3cec0c8bf4 40 {
mjr 17:ab3cec0c8bf4 41 public:
mjr 17:ab3cec0c8bf4 42 PlungerSensor() : ccd(CCD_SO_PIN)
mjr 17:ab3cec0c8bf4 43 {
mjr 17:ab3cec0c8bf4 44 }
mjr 17:ab3cec0c8bf4 45
mjr 17:ab3cec0c8bf4 46 // initialize
mjr 17:ab3cec0c8bf4 47 void init()
mjr 17:ab3cec0c8bf4 48 {
mjr 17:ab3cec0c8bf4 49 // flush any random power-on values from the CCD's integration
mjr 17:ab3cec0c8bf4 50 // capacitors, and start the first integration cycle
mjr 17:ab3cec0c8bf4 51 ccd.clear();
mjr 17:ab3cec0c8bf4 52 }
mjr 17:ab3cec0c8bf4 53
mjr 17:ab3cec0c8bf4 54 // Perform a low-res scan of the sensor.
mjr 17:ab3cec0c8bf4 55 int lowResScan()
mjr 17:ab3cec0c8bf4 56 {
mjr 17:ab3cec0c8bf4 57
mjr 17:ab3cec0c8bf4 58 // read the pixels at low resolution
mjr 17:ab3cec0c8bf4 59 const int nlpix = 32;
mjr 17:ab3cec0c8bf4 60 uint16_t pix[nlpix];
mjr 17:ab3cec0c8bf4 61 ccd.read(pix, nlpix);
mjr 17:ab3cec0c8bf4 62
mjr 17:ab3cec0c8bf4 63 // determine which end is brighter
mjr 17:ab3cec0c8bf4 64 uint16_t p1 = pix[0];
mjr 17:ab3cec0c8bf4 65 uint16_t p2 = pix[nlpix-1];
mjr 17:ab3cec0c8bf4 66 int si = 1, di = 1;
mjr 17:ab3cec0c8bf4 67 if (p1 < p2)
mjr 17:ab3cec0c8bf4 68 si = nlpix, di = -1;
mjr 17:ab3cec0c8bf4 69
mjr 17:ab3cec0c8bf4 70 // figure the shadow edge threshold - just use the midpoint
mjr 17:ab3cec0c8bf4 71 // of the levels at the bright and dark ends
mjr 17:ab3cec0c8bf4 72 uint16_t shadow = uint16_t((long(p1) + long(p2))/2);
mjr 17:ab3cec0c8bf4 73
mjr 17:ab3cec0c8bf4 74 // find the current tip position
mjr 17:ab3cec0c8bf4 75 for (int n = 0 ; n < nlpix ; ++n, si += di)
mjr 17:ab3cec0c8bf4 76 {
mjr 17:ab3cec0c8bf4 77 // check to see if we found the shadow
mjr 17:ab3cec0c8bf4 78 if (pix[si] <= shadow)
mjr 17:ab3cec0c8bf4 79 {
mjr 17:ab3cec0c8bf4 80 // got it - normalize it to normal 'npix' resolution and
mjr 17:ab3cec0c8bf4 81 // return the result
mjr 17:ab3cec0c8bf4 82 return n*npix/nlpix;
mjr 17:ab3cec0c8bf4 83 }
mjr 17:ab3cec0c8bf4 84 }
mjr 17:ab3cec0c8bf4 85
mjr 17:ab3cec0c8bf4 86 // didn't find a shadow - assume the whole array is in shadow (so
mjr 17:ab3cec0c8bf4 87 // the edge is at the zero pixel point)
mjr 17:ab3cec0c8bf4 88 return 0;
mjr 17:ab3cec0c8bf4 89 }
mjr 17:ab3cec0c8bf4 90
mjr 17:ab3cec0c8bf4 91 // Perform a high-res scan of the sensor.
mjr 17:ab3cec0c8bf4 92 bool highResScan(int &pos)
mjr 17:ab3cec0c8bf4 93 {
mjr 17:ab3cec0c8bf4 94 // read the array
mjr 18:5e890ebd0023 95 ccd.read(pix, npix);
mjr 17:ab3cec0c8bf4 96
mjr 18:5e890ebd0023 97 // get the brightness at each end of the sensor
mjr 18:5e890ebd0023 98 long b1 = pix[0];
mjr 18:5e890ebd0023 99 long b2 = pix[npix-1];
mjr 17:ab3cec0c8bf4 100
mjr 17:ab3cec0c8bf4 101 // Work from the bright end to the dark end. VP interprets the
mjr 17:ab3cec0c8bf4 102 // Z axis value as the amount the plunger is pulled: zero is the
mjr 17:ab3cec0c8bf4 103 // rest position, and the axis maximum is fully pulled. So we
mjr 17:ab3cec0c8bf4 104 // essentially want to report how much of the sensor is lit,
mjr 17:ab3cec0c8bf4 105 // since this increases as the plunger is pulled back.
mjr 18:5e890ebd0023 106 int si = 0, di = 1;
mjr 18:5e890ebd0023 107 long hi = b1;
mjr 18:5e890ebd0023 108 if (b1 < b2)
mjr 18:5e890ebd0023 109 si = npix - 1, di = -1, hi = b2;
mjr 17:ab3cec0c8bf4 110
mjr 17:ab3cec0c8bf4 111 // Figure the shadow threshold. In practice, the portion of the
mjr 17:ab3cec0c8bf4 112 // sensor that's not in shadow has all pixels consistently near
mjr 17:ab3cec0c8bf4 113 // saturation; the first drop in brightness is pretty reliably the
mjr 17:ab3cec0c8bf4 114 // start of the shadow. So set the threshold level to be closer
mjr 17:ab3cec0c8bf4 115 // to the bright end's brightness level, so that we detect the leading
mjr 17:ab3cec0c8bf4 116 // edge if the shadow isn't perfectly sharp. Use the point 1/3 of
mjr 17:ab3cec0c8bf4 117 // the way down from the high top the low side, so:
mjr 17:ab3cec0c8bf4 118 //
mjr 17:ab3cec0c8bf4 119 // threshold = lo + (hi - lo)*2/3
mjr 17:ab3cec0c8bf4 120 // = lo + hi*2/3 - lo*2/3
mjr 17:ab3cec0c8bf4 121 // = lo - lo*2/3 + hi*2/3
mjr 17:ab3cec0c8bf4 122 // = lo*1/3 + hi*2/3
mjr 17:ab3cec0c8bf4 123 // = (lo + hi*2)/3
mjr 17:ab3cec0c8bf4 124 //
mjr 18:5e890ebd0023 125 // Now, 'lo' is always one of b1 or b2, and 'hi' is the other
mjr 18:5e890ebd0023 126 // one, so we can rewrite this as:
mjr 18:5e890ebd0023 127 long midpt = (b1 + b2 + hi)/3;
mjr 17:ab3cec0c8bf4 128
mjr 17:ab3cec0c8bf4 129 // If we have enough contrast, proceed with the scan.
mjr 17:ab3cec0c8bf4 130 //
mjr 17:ab3cec0c8bf4 131 // If the bright end and dark end don't differ by enough, skip this
mjr 17:ab3cec0c8bf4 132 // reading entirely. Either we have an overexposed or underexposed frame,
mjr 17:ab3cec0c8bf4 133 // or the sensor is misaligned and is either fully in or out of shadow
mjr 17:ab3cec0c8bf4 134 // (it's supposed to be mounted such that the edge of the shadow always
mjr 17:ab3cec0c8bf4 135 // falls within the sensor, for any possible plunger position).
mjr 18:5e890ebd0023 136 if (labs(b1 - b2) > 0x1000)
mjr 17:ab3cec0c8bf4 137 {
mjr 17:ab3cec0c8bf4 138 uint16_t *pixp = pix + si;
mjr 18:5e890ebd0023 139 for (int n = 0 ; n < npix ; ++n, pixp += di)
mjr 17:ab3cec0c8bf4 140 {
mjr 17:ab3cec0c8bf4 141 // if we've crossed the midpoint, report this position
mjr 18:5e890ebd0023 142 if (long(*pixp) < midpt)
mjr 17:ab3cec0c8bf4 143 {
mjr 17:ab3cec0c8bf4 144 // note the new position
mjr 17:ab3cec0c8bf4 145 pos = n;
mjr 17:ab3cec0c8bf4 146 return true;
mjr 17:ab3cec0c8bf4 147 }
mjr 17:ab3cec0c8bf4 148 }
mjr 17:ab3cec0c8bf4 149 }
mjr 17:ab3cec0c8bf4 150
mjr 17:ab3cec0c8bf4 151 // we didn't find a shadow - return no reading
mjr 17:ab3cec0c8bf4 152 return false;
mjr 17:ab3cec0c8bf4 153 }
mjr 17:ab3cec0c8bf4 154
mjr 17:ab3cec0c8bf4 155 // send an exposure report to the joystick interface
mjr 17:ab3cec0c8bf4 156 void sendExposureReport(USBJoystick &js)
mjr 17:ab3cec0c8bf4 157 {
mjr 17:ab3cec0c8bf4 158 // send reports for all pixels
mjr 17:ab3cec0c8bf4 159 int idx = 0;
mjr 17:ab3cec0c8bf4 160 while (idx < npix)
mjr 18:5e890ebd0023 161 {
mjr 17:ab3cec0c8bf4 162 js.updateExposure(idx, npix, pix);
mjr 18:5e890ebd0023 163 wait_ms(1);
mjr 18:5e890ebd0023 164 }
mjr 17:ab3cec0c8bf4 165
mjr 17:ab3cec0c8bf4 166 // The pixel dump requires many USB reports, since each report
mjr 17:ab3cec0c8bf4 167 // can only send a few pixel values. An integration cycle has
mjr 17:ab3cec0c8bf4 168 // been running all this time, since each read starts a new
mjr 17:ab3cec0c8bf4 169 // cycle. Our timing is longer than usual on this round, so
mjr 17:ab3cec0c8bf4 170 // the integration won't be comparable to a normal cycle. Throw
mjr 17:ab3cec0c8bf4 171 // this one away by doing a read now, and throwing it away - that
mjr 17:ab3cec0c8bf4 172 // will get the timing of the *next* cycle roughly back to normal.
mjr 17:ab3cec0c8bf4 173 ccd.read(pix, npix);
mjr 17:ab3cec0c8bf4 174 }
mjr 17:ab3cec0c8bf4 175
mjr 17:ab3cec0c8bf4 176 private:
mjr 17:ab3cec0c8bf4 177 // pixel buffer
mjr 17:ab3cec0c8bf4 178 uint16_t pix[npix];
mjr 17:ab3cec0c8bf4 179
mjr 17:ab3cec0c8bf4 180 // the low-level interface to the CCD hardware
mjr 17:ab3cec0c8bf4 181 TSL1410R<CCD_SI_PIN, CCD_CLOCK_PIN> ccd;
mjr 17:ab3cec0c8bf4 182 };