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Dependencies:   FastAnalogIn FastIO FastPWM SimpleDMA USBDevice mbed

Fork of Pinscape_Controller by Mike R

ccdSensor.h@25:e22b88bd783a, 2015-09-01 (annotated)

Committer:
mjr
Date:
Tue Sep 01 04:27:15 2015 +0000
Revision:
25:e22b88bd783a
Parent:
18:5e890ebd0023 
Centralized the CCD pixel count setting to a single config.h option; added an option to config.h to select the board's mounting orientation for the accelerometer

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 25:e22b88bd783a 8 // Number of pixels we read from the CCD on each frame. Use the
mjr 25:e22b88bd783a 9 // sample size from config.h.
mjr 25:e22b88bd783a 10 const int npix = CCD_NPIXELS_SAMPLED;
mjr 17:ab3cec0c8bf4 11
mjr 25:e22b88bd783a 12 // PlungerSensor interface implementation for the CCD
mjr 17:ab3cec0c8bf4 13 class PlungerSensor
mjr 17:ab3cec0c8bf4 14 {
mjr 17:ab3cec0c8bf4 15 public:
mjr 17:ab3cec0c8bf4 16 PlungerSensor() : ccd(CCD_SO_PIN)
mjr 17:ab3cec0c8bf4 17 {
mjr 17:ab3cec0c8bf4 18 }
mjr 17:ab3cec0c8bf4 19
mjr 17:ab3cec0c8bf4 20 // initialize
mjr 17:ab3cec0c8bf4 21 void init()
mjr 17:ab3cec0c8bf4 22 {
mjr 17:ab3cec0c8bf4 23 // flush any random power-on values from the CCD's integration
mjr 17:ab3cec0c8bf4 24 // capacitors, and start the first integration cycle
mjr 17:ab3cec0c8bf4 25 ccd.clear();
mjr 17:ab3cec0c8bf4 26 }
mjr 17:ab3cec0c8bf4 27
mjr 17:ab3cec0c8bf4 28 // Perform a low-res scan of the sensor.
mjr 17:ab3cec0c8bf4 29 int lowResScan()
mjr 17:ab3cec0c8bf4 30 {
mjr 17:ab3cec0c8bf4 31
mjr 17:ab3cec0c8bf4 32 // read the pixels at low resolution
mjr 17:ab3cec0c8bf4 33 const int nlpix = 32;
mjr 17:ab3cec0c8bf4 34 uint16_t pix[nlpix];
mjr 17:ab3cec0c8bf4 35 ccd.read(pix, nlpix);
mjr 17:ab3cec0c8bf4 36
mjr 17:ab3cec0c8bf4 37 // determine which end is brighter
mjr 17:ab3cec0c8bf4 38 uint16_t p1 = pix[0];
mjr 17:ab3cec0c8bf4 39 uint16_t p2 = pix[nlpix-1];
mjr 17:ab3cec0c8bf4 40 int si = 1, di = 1;
mjr 17:ab3cec0c8bf4 41 if (p1 < p2)
mjr 17:ab3cec0c8bf4 42 si = nlpix, di = -1;
mjr 17:ab3cec0c8bf4 43
mjr 17:ab3cec0c8bf4 44 // figure the shadow edge threshold - just use the midpoint
mjr 17:ab3cec0c8bf4 45 // of the levels at the bright and dark ends
mjr 17:ab3cec0c8bf4 46 uint16_t shadow = uint16_t((long(p1) + long(p2))/2);
mjr 17:ab3cec0c8bf4 47
mjr 17:ab3cec0c8bf4 48 // find the current tip position
mjr 17:ab3cec0c8bf4 49 for (int n = 0 ; n < nlpix ; ++n, si += di)
mjr 17:ab3cec0c8bf4 50 {
mjr 17:ab3cec0c8bf4 51 // check to see if we found the shadow
mjr 17:ab3cec0c8bf4 52 if (pix[si] <= shadow)
mjr 17:ab3cec0c8bf4 53 {
mjr 17:ab3cec0c8bf4 54 // got it - normalize it to normal 'npix' resolution and
mjr 17:ab3cec0c8bf4 55 // return the result
mjr 17:ab3cec0c8bf4 56 return n*npix/nlpix;
mjr 17:ab3cec0c8bf4 57 }
mjr 17:ab3cec0c8bf4 58 }
mjr 17:ab3cec0c8bf4 59
mjr 17:ab3cec0c8bf4 60 // didn't find a shadow - assume the whole array is in shadow (so
mjr 17:ab3cec0c8bf4 61 // the edge is at the zero pixel point)
mjr 17:ab3cec0c8bf4 62 return 0;
mjr 17:ab3cec0c8bf4 63 }
mjr 17:ab3cec0c8bf4 64
mjr 17:ab3cec0c8bf4 65 // Perform a high-res scan of the sensor.
mjr 17:ab3cec0c8bf4 66 bool highResScan(int &pos)
mjr 17:ab3cec0c8bf4 67 {
mjr 17:ab3cec0c8bf4 68 // read the array
mjr 18:5e890ebd0023 69 ccd.read(pix, npix);
mjr 17:ab3cec0c8bf4 70
mjr 18:5e890ebd0023 71 // get the brightness at each end of the sensor
mjr 18:5e890ebd0023 72 long b1 = pix[0];
mjr 18:5e890ebd0023 73 long b2 = pix[npix-1];
mjr 17:ab3cec0c8bf4 74
mjr 17:ab3cec0c8bf4 75 // Work from the bright end to the dark end. VP interprets the
mjr 17:ab3cec0c8bf4 76 // Z axis value as the amount the plunger is pulled: zero is the
mjr 17:ab3cec0c8bf4 77 // rest position, and the axis maximum is fully pulled. So we
mjr 17:ab3cec0c8bf4 78 // essentially want to report how much of the sensor is lit,
mjr 17:ab3cec0c8bf4 79 // since this increases as the plunger is pulled back.
mjr 18:5e890ebd0023 80 int si = 0, di = 1;
mjr 18:5e890ebd0023 81 long hi = b1;
mjr 18:5e890ebd0023 82 if (b1 < b2)
mjr 18:5e890ebd0023 83 si = npix - 1, di = -1, hi = b2;
mjr 17:ab3cec0c8bf4 84
mjr 17:ab3cec0c8bf4 85 // Figure the shadow threshold. In practice, the portion of the
mjr 17:ab3cec0c8bf4 86 // sensor that's not in shadow has all pixels consistently near
mjr 17:ab3cec0c8bf4 87 // saturation; the first drop in brightness is pretty reliably the
mjr 17:ab3cec0c8bf4 88 // start of the shadow. So set the threshold level to be closer
mjr 17:ab3cec0c8bf4 89 // to the bright end's brightness level, so that we detect the leading
mjr 17:ab3cec0c8bf4 90 // edge if the shadow isn't perfectly sharp. Use the point 1/3 of
mjr 17:ab3cec0c8bf4 91 // the way down from the high top the low side, so:
mjr 17:ab3cec0c8bf4 92 //
mjr 17:ab3cec0c8bf4 93 // threshold = lo + (hi - lo)*2/3
mjr 17:ab3cec0c8bf4 94 // = lo + hi*2/3 - lo*2/3
mjr 17:ab3cec0c8bf4 95 // = lo - lo*2/3 + hi*2/3
mjr 17:ab3cec0c8bf4 96 // = lo*1/3 + hi*2/3
mjr 17:ab3cec0c8bf4 97 // = (lo + hi*2)/3
mjr 17:ab3cec0c8bf4 98 //
mjr 18:5e890ebd0023 99 // Now, 'lo' is always one of b1 or b2, and 'hi' is the other
mjr 18:5e890ebd0023 100 // one, so we can rewrite this as:
mjr 18:5e890ebd0023 101 long midpt = (b1 + b2 + hi)/3;
mjr 17:ab3cec0c8bf4 102
mjr 17:ab3cec0c8bf4 103 // If we have enough contrast, proceed with the scan.
mjr 17:ab3cec0c8bf4 104 //
mjr 17:ab3cec0c8bf4 105 // If the bright end and dark end don't differ by enough, skip this
mjr 17:ab3cec0c8bf4 106 // reading entirely. Either we have an overexposed or underexposed frame,
mjr 17:ab3cec0c8bf4 107 // or the sensor is misaligned and is either fully in or out of shadow
mjr 17:ab3cec0c8bf4 108 // (it's supposed to be mounted such that the edge of the shadow always
mjr 17:ab3cec0c8bf4 109 // falls within the sensor, for any possible plunger position).
mjr 18:5e890ebd0023 110 if (labs(b1 - b2) > 0x1000)
mjr 17:ab3cec0c8bf4 111 {
mjr 17:ab3cec0c8bf4 112 uint16_t *pixp = pix + si;
mjr 18:5e890ebd0023 113 for (int n = 0 ; n < npix ; ++n, pixp += di)
mjr 17:ab3cec0c8bf4 114 {
mjr 17:ab3cec0c8bf4 115 // if we've crossed the midpoint, report this position
mjr 18:5e890ebd0023 116 if (long(*pixp) < midpt)
mjr 17:ab3cec0c8bf4 117 {
mjr 17:ab3cec0c8bf4 118 // note the new position
mjr 17:ab3cec0c8bf4 119 pos = n;
mjr 17:ab3cec0c8bf4 120 return true;
mjr 17:ab3cec0c8bf4 121 }
mjr 17:ab3cec0c8bf4 122 }
mjr 17:ab3cec0c8bf4 123 }
mjr 17:ab3cec0c8bf4 124
mjr 17:ab3cec0c8bf4 125 // we didn't find a shadow - return no reading
mjr 17:ab3cec0c8bf4 126 return false;
mjr 17:ab3cec0c8bf4 127 }
mjr 17:ab3cec0c8bf4 128
mjr 17:ab3cec0c8bf4 129 // send an exposure report to the joystick interface
mjr 17:ab3cec0c8bf4 130 void sendExposureReport(USBJoystick &js)
mjr 17:ab3cec0c8bf4 131 {
mjr 17:ab3cec0c8bf4 132 // send reports for all pixels
mjr 17:ab3cec0c8bf4 133 int idx = 0;
mjr 17:ab3cec0c8bf4 134 while (idx < npix)
mjr 18:5e890ebd0023 135 {
mjr 17:ab3cec0c8bf4 136 js.updateExposure(idx, npix, pix);
mjr 18:5e890ebd0023 137 wait_ms(1);
mjr 18:5e890ebd0023 138 }
mjr 17:ab3cec0c8bf4 139
mjr 17:ab3cec0c8bf4 140 // The pixel dump requires many USB reports, since each report
mjr 17:ab3cec0c8bf4 141 // can only send a few pixel values. An integration cycle has
mjr 17:ab3cec0c8bf4 142 // been running all this time, since each read starts a new
mjr 17:ab3cec0c8bf4 143 // cycle. Our timing is longer than usual on this round, so
mjr 17:ab3cec0c8bf4 144 // the integration won't be comparable to a normal cycle. Throw
mjr 17:ab3cec0c8bf4 145 // this one away by doing a read now, and throwing it away - that
mjr 17:ab3cec0c8bf4 146 // will get the timing of the *next* cycle roughly back to normal.
mjr 17:ab3cec0c8bf4 147 ccd.read(pix, npix);
mjr 17:ab3cec0c8bf4 148 }
mjr 17:ab3cec0c8bf4 149
mjr 17:ab3cec0c8bf4 150 private:
mjr 17:ab3cec0c8bf4 151 // pixel buffer
mjr 17:ab3cec0c8bf4 152 uint16_t pix[npix];
mjr 17:ab3cec0c8bf4 153
mjr 17:ab3cec0c8bf4 154 // the low-level interface to the CCD hardware
mjr 17:ab3cec0c8bf4 155 TSL1410R<CCD_SI_PIN, CCD_CLOCK_PIN> ccd;
mjr 17:ab3cec0c8bf4 156 };