Arnaud VALLEY / Mbed 2 deprecated Pinscape_Controller_V2_arnoz

Mirror with some correction

Dependencies:   mbed FastIO FastPWM USBDevice

Plunger/tcd1103Sensor.h@109:310ac82cbbee, 2020-04-18 (annotated)

Committer:
mjr
Date:
Sat Apr 18 19:08:55 2020 +0000
Revision:
109:310ac82cbbee
Parent:
106:e9e3b46132c1 
TCD1103 DMA setup time padding to fix sporadic missed first pixel in transfer; fix TV ON so that the TV ON IR commands don't have to be grouped in the IR command first slots

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mjr 100:1ff35c07217c 1 // Toshiba TCD1103 linear image sensors
mjr 100:1ff35c07217c 2 //
mjr 100:1ff35c07217c 3 // This sensor is similar to the original TSL1410R in both its electronic
mjr 100:1ff35c07217c 4 // interface and the theory of operation. The details of the electronics
mjr 100:1ff35c07217c 5 // are different enough that we can't reuse the same code at the hardware
mjr 100:1ff35c07217c 6 // interface level, but the principle of operation is similar: the sensor
mjr 100:1ff35c07217c 7 // provides a serial interface to a file of pixels transferred as analog
mjr 100:1ff35c07217c 8 // voltage levels representing the charge collected.
mjr 100:1ff35c07217c 9 //
mjr 100:1ff35c07217c 10 // As with the TSL1410R, we position the sensor so that the pixel row is
mjr 104:6e06e0f4b476 11 // aligned with the plunger axis, and we detect the plunger position by
mjr 104:6e06e0f4b476 12 // looking for a dark/light edge at the end of the plunger. However,
mjr 104:6e06e0f4b476 13 // the optics for this sensor are very different because of the sensor's
mjr 104:6e06e0f4b476 14 // size. The TSL1410R is by some magical coincidence the same size as
mjr 104:6e06e0f4b476 15 // the plunger travel range, so we set that sensor up so that the plunger
mjr 104:6e06e0f4b476 16 // is backlit with respect to the sensor, and simply casts a shadow on
mjr 104:6e06e0f4b476 17 // the sensor. The TCD1103, in contrast, has a pixel array that's only
mjr 104:6e06e0f4b476 18 // 8mm long, so we can't use the direct shadow approach. Instead, we
mjr 104:6e06e0f4b476 19 // have to use a lens to focus an image of the plunger on the sensor.
mjr 104:6e06e0f4b476 20 // With a focused image, we can front-light the plunger and take a picture
mjr 104:6e06e0f4b476 21 // of the plunger itself rather than of an occluded back-light.
mjr 100:1ff35c07217c 22 //
mjr 104:6e06e0f4b476 23 // Even though we use "edge sensing", this class isn't based on the
mjr 104:6e06e0f4b476 24 // PlungerSensorEdgePos class. Our sensing algorithm is a little different,
mjr 104:6e06e0f4b476 25 // and much simpler, because we're working with a proper image of the
mjr 104:6e06e0f4b476 26 // plunger, rather than an image of its shadow. The shadow tends to be
mjr 104:6e06e0f4b476 27 // rather fuzzy, and the TSL14xx sensors were pretty noisy, so we had to
mjr 104:6e06e0f4b476 28 // work fairly hard to distinguish an edge in the image from a noise spike.
mjr 104:6e06e0f4b476 29 // This sensor has very low noise, and the focused image produces a sharp
mjr 104:6e06e0f4b476 30 // edge, so we can use a more straightforward algorithm that just looks
mjr 104:6e06e0f4b476 31 // for the first bright spot.
mjr 104:6e06e0f4b476 32 //
mjr 104:6e06e0f4b476 33 // The TCD1103 uses a negative image: brighter pixels are represented by
mjr 104:6e06e0f4b476 34 // lower numbers. The electronics of the sensor are such that the dynamic
mjr 104:6e06e0f4b476 35 // range for the pixel analag voltage signal (which is what our pixel
mjr 104:6e06e0f4b476 36 // elements represent) is only about 1V, or about 30% of the 3.3V range of
mjr 104:6e06e0f4b476 37 // the ADC. Dark pixels read at about 2V (about 167 after 8-bit ADC
mjr 104:6e06e0f4b476 38 // quantization), and saturated pixels read at 1V (78 on the ADC). So our
mjr 104:6e06e0f4b476 39 // effective dynamic range after quantization is about 100 steps. That
mjr 104:6e06e0f4b476 40 // would be pretty terrible if the goal were to take pictures for an art
mjr 104:6e06e0f4b476 41 // gallery, and there are things we could do in the electronic interface
mjr 106:e9e3b46132c1 42 // to improve it. In particular, we could use an op-amp to expand the
mjr 104:6e06e0f4b476 43 // voltage range on the ADC input and remove the DC offset, so that the
mjr 106:e9e3b46132c1 44 // signal going into the ADC covers the ADC's full 0V - 3.3V range. That
mjr 106:e9e3b46132c1 45 // technique is actually used in some other projects using this sensor
mjr 106:e9e3b46132c1 46 // where the goal is to yield pictures as the end result. But it's
mjr 106:e9e3b46132c1 47 // pretty complicated to set up and fine-tune to get the voltage range
mjr 106:e9e3b46132c1 48 // expansion just right, and we really don't need it; the edge detection
mjr 106:e9e3b46132c1 49 // works fine with what we get directly from the sensor.
mjr 106:e9e3b46132c1 50
mjr 100:1ff35c07217c 51
mjr 104:6e06e0f4b476 52
mjr 104:6e06e0f4b476 53 #include "plunger.h"
mjr 100:1ff35c07217c 54 #include "TCD1103.h"
mjr 100:1ff35c07217c 55
mjr 100:1ff35c07217c 56 template <bool invertedLogicGates>
mjr 100:1ff35c07217c 57 class PlungerSensorImageInterfaceTCD1103: public PlungerSensorImageInterface
mjr 100:1ff35c07217c 58 {
mjr 100:1ff35c07217c 59 public:
mjr 100:1ff35c07217c 60 PlungerSensorImageInterfaceTCD1103(PinName fm, PinName os, PinName icg, PinName sh)
mjr 109:310ac82cbbee 61 : PlungerSensorImageInterface(1546), sensor(fm, os, icg, sh)
mjr 100:1ff35c07217c 62 {
mjr 100:1ff35c07217c 63 }
mjr 100:1ff35c07217c 64
mjr 100:1ff35c07217c 65 // is the sensor ready?
mjr 100:1ff35c07217c 66 virtual bool ready() { return sensor.ready(); }
mjr 100:1ff35c07217c 67
mjr 101:755f44622abc 68 virtual void init() { }
mjr 100:1ff35c07217c 69
mjr 100:1ff35c07217c 70 // get the average sensor scan time
mjr 100:1ff35c07217c 71 virtual uint32_t getAvgScanTime() { return sensor.getAvgScanTime(); }
mjr 100:1ff35c07217c 72
mjr 101:755f44622abc 73 virtual void readPix(uint8_t* &pix, uint32_t &t)
mjr 100:1ff35c07217c 74 {
mjr 100:1ff35c07217c 75 // get the image array from the last capture
mjr 104:6e06e0f4b476 76 sensor.getPix(pix, t);
mjr 100:1ff35c07217c 77 }
mjr 100:1ff35c07217c 78
mjr 101:755f44622abc 79 virtual void releasePix() { sensor.releasePix(); }
mjr 101:755f44622abc 80
mjr 101:755f44622abc 81 virtual void setMinIntTime(uint32_t us) { sensor.setMinIntTime(us); }
mjr 100:1ff35c07217c 82
mjr 100:1ff35c07217c 83 // the low-level interface to the TSL14xx sensor
mjr 100:1ff35c07217c 84 TCD1103<invertedLogicGates> sensor;
mjr 100:1ff35c07217c 85 };
mjr 100:1ff35c07217c 86
mjr 100:1ff35c07217c 87 template<bool invertedLogicGates>
mjr 104:6e06e0f4b476 88 class PlungerSensorTCD1103: public PlungerSensorImage<int>
mjr 100:1ff35c07217c 89 {
mjr 100:1ff35c07217c 90 public:
mjr 100:1ff35c07217c 91 PlungerSensorTCD1103(PinName fm, PinName os, PinName icg, PinName sh)
mjr 109:310ac82cbbee 92 : PlungerSensorImage(sensor, 1546, 1545, true), sensor(fm, os, icg, sh)
mjr 100:1ff35c07217c 93 {
mjr 100:1ff35c07217c 94 }
mjr 100:1ff35c07217c 95
mjr 100:1ff35c07217c 96 protected:
mjr 104:6e06e0f4b476 97 // Process an image. This seeks the first dark-to-light edge in the image.
mjr 104:6e06e0f4b476 98 // We assume that the background (open space behind the plunger) has a
mjr 104:6e06e0f4b476 99 // dark (minimally reflective) backdrop, and that the tip of the plunger
mjr 104:6e06e0f4b476 100 // has a bright white strip right at the end. So the end of the plunger
mjr 104:6e06e0f4b476 101 // should be easily identifiable in the image as the first bright edge
mjr 104:6e06e0f4b476 102 // we see starting at the "far" end.
mjr 104:6e06e0f4b476 103 virtual bool process(const uint8_t *pix, int n, int &pos, int& /*processResult*/)
mjr 104:6e06e0f4b476 104 {
mjr 109:310ac82cbbee 105 // The TCD1103's pixel file that it reports on the wire has the
mjr 109:310ac82cbbee 106 // following internal structure:
mjr 109:310ac82cbbee 107 //
mjr 109:310ac82cbbee 108 // 16 dummy elements, fixed at the dark charge level
mjr 109:310ac82cbbee 109 // 13 light-shielded pixels (live pixels, covered with a shade in the sensor)
mjr 109:310ac82cbbee 110 // 3 dummy "buffer" pixels (to allow for variation in shade alignment)
mjr 109:310ac82cbbee 111 // 1500 image pixels
mjr 109:310ac82cbbee 112 // 14 dummy elements (the data sheet doesn't say exactly what these are physically)
mjr 109:310ac82cbbee 113 //
mjr 109:310ac82cbbee 114 // The sensor holds the 16 dummy elements at the dark charge level,
mjr 109:310ac82cbbee 115 // so they provide a reference point for the darkest reading possible.
mjr 109:310ac82cbbee 116 // The light-shielded pixels serve essentially the same purpose, in
mjr 109:310ac82cbbee 117 // that they *also* should read out at the dark charge level. But
mjr 109:310ac82cbbee 118 // the shaded pixels can be also used for diagnostics, to distinguish
mjr 109:310ac82cbbee 119 // between problems in the CCD proper and problems in the interface
mjr 109:310ac82cbbee 120 // electronics. If the dummy elements are reading at the dark level
mjr 109:310ac82cbbee 121 // but the shielded pixels aren't, you have a CCD problem; if the
mjr 109:310ac82cbbee 122 // dummy pixels aren't reading at the dark level, the interface
mjr 109:310ac82cbbee 123 // electronics are suspect.
mjr 109:310ac82cbbee 124 //
mjr 109:310ac82cbbee 125 // For our purposes, we can simply ignore the dummy pixels at either
mjr 109:310ac82cbbee 126 // end. The diagnostic status report for the Config Tool sends the
mjr 109:310ac82cbbee 127 // full view including the dummy pixels, so any diagnostics that the
mjr 109:310ac82cbbee 128 // user wants to do using the dummy pixels can be done on the PC side.
mjr 109:310ac82cbbee 129 //
mjr 109:310ac82cbbee 130 // Deduct the dummy pixels so that we only scan the true image
mjr 109:310ac82cbbee 131 // pixels in our search for the plunger edge.
mjr 109:310ac82cbbee 132 int startOfs = 32;
mjr 109:310ac82cbbee 133 n -= 32 + 14;
mjr 109:310ac82cbbee 134
mjr 104:6e06e0f4b476 135 // Scan the pixel array to determine the actual dynamic range
mjr 104:6e06e0f4b476 136 // of this image. That will let us determine what consistutes
mjr 104:6e06e0f4b476 137 // "bright" when we're looking for the bright spot.
mjr 104:6e06e0f4b476 138 uint8_t pixMin = 255, pixMax = 0;
mjr 109:310ac82cbbee 139 const uint8_t *p = pix + startOfs;
mjr 104:6e06e0f4b476 140 for (int i = n; i != 0; --i)
mjr 104:6e06e0f4b476 141 {
mjr 104:6e06e0f4b476 142 uint8_t c = *p++;
mjr 104:6e06e0f4b476 143 if (c < pixMin) pixMin = c;
mjr 104:6e06e0f4b476 144 if (c > pixMax) pixMax = c;
mjr 104:6e06e0f4b476 145 }
mjr 104:6e06e0f4b476 146
mjr 104:6e06e0f4b476 147 // Figure the threshold brightness for the bright spot as halfway
mjr 104:6e06e0f4b476 148 // between the min and max.
mjr 104:6e06e0f4b476 149 uint8_t threshold = (pixMin + pixMax)/2;
mjr 104:6e06e0f4b476 150
mjr 104:6e06e0f4b476 151 // Scan for the first bright-enough pixel. Remember that we're
mjr 104:6e06e0f4b476 152 // working with a negative image, so "brighter" is "less than".
mjr 109:310ac82cbbee 153 p = pix + startOfs;
mjr 104:6e06e0f4b476 154 for (int i = n; i != 0; --i, ++p)
mjr 104:6e06e0f4b476 155 {
mjr 104:6e06e0f4b476 156 if (*p < threshold)
mjr 104:6e06e0f4b476 157 {
mjr 104:6e06e0f4b476 158 // got it - report this position
mjr 104:6e06e0f4b476 159 pos = p - pix;
mjr 104:6e06e0f4b476 160 return true;
mjr 104:6e06e0f4b476 161 }
mjr 104:6e06e0f4b476 162 }
mjr 104:6e06e0f4b476 163
mjr 104:6e06e0f4b476 164 // no edge found - report failure
mjr 104:6e06e0f4b476 165 return false;
mjr 104:6e06e0f4b476 166 }
mjr 104:6e06e0f4b476 167
mjr 104:6e06e0f4b476 168 // Use a fixed orientation for this sensor. The shadow-edge sensors
mjr 104:6e06e0f4b476 169 // try to infer the direction by checking which end of the image is
mjr 104:6e06e0f4b476 170 // brighter, which works well for the shadow sensors because the back
mjr 104:6e06e0f4b476 171 // end of the image will always be in shadow. But for this sensor,
mjr 104:6e06e0f4b476 172 // we're taking an image of the plunger (not its shadow), and the
mjr 104:6e06e0f4b476 173 // back end of the plunger is the part with the spring, which has a
mjr 104:6e06e0f4b476 174 // fuzzy and complex reflectivity pattern because of the spring.
mjr 104:6e06e0f4b476 175 // So for this sensor, it's better to insist that the user sets it
mjr 104:6e06e0f4b476 176 // up in a canonical orientation. That's a reasaonble expectation
mjr 104:6e06e0f4b476 177 // for this sensor anyway, because the physical installation won't
mjr 104:6e06e0f4b476 178 // be as ad hoc as the TSL1410R setup, which only required that you
mjr 104:6e06e0f4b476 179 // mounted the sensor itself. In this case, you have to build a
mjr 104:6e06e0f4b476 180 // circuit board and mount a lens on it, so it's reasonable to
mjr 104:6e06e0f4b476 181 // expect that everyone will be using the mounting apparatus plans
mjr 104:6e06e0f4b476 182 // that we'll detail in the build guide. In any case, we'll just
mjr 104:6e06e0f4b476 183 // make it clear in the instructions that you have to mount the
mjr 104:6e06e0f4b476 184 // sensor in a certain orientation.
mjr 104:6e06e0f4b476 185 virtual int getOrientation() const { return 1; }
mjr 104:6e06e0f4b476 186
mjr 104:6e06e0f4b476 187 // the hardware sensor interface
mjr 100:1ff35c07217c 188 PlungerSensorImageInterfaceTCD1103<invertedLogicGates> sensor;
mjr 100:1ff35c07217c 189 };