Build Instructions

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• 1

  Electrical specifications of the sensor

  
  

  item	content	remarks
  Power-supply voltage	5V	Assuming USB power supply
  controller voltage	5V, 3.3V	Signal output 3.3V
  consumption current	180mA (scan time 1.2mS)	Typical value for single board
  power consumption	１W	Typical value for single board
  Scan time board alone	1.2mS or more, 1 channel 150uS or more
  Scan time parallel continuation	800uS or more, 1 channel 100uS or more※

  ※In order not to reduce the detection distance, it is desirable to use 150uS or more per channel.
  

• 2

  Hardware of the sensor

  Main board

  Main board pinout (JP1)

  pin number	PIN name	explanation
  1	+5V	Vcc 5V
  2	GND	GND
  3	A	Sensor channel 0bit
  4	B	Sensor channel 1bit
  5	C	Sensor channel 2bit
  6	SS	SPI Slave-Select (active-Low) Substrate selection when connecting in parallel
  7	MOSI	SPI Input
  8	MISO	SPI Output (3.3V/5V switching JP2)
  9	SCLK	SPI Clock
  10	SEL_SEN	SPI selection High: Sensor (AD converter), Low: CLED
  11	OE_ILED	ILED Output Enable ※ILED: Infrared LED  ILED enable/disable * Infrared radiation is automatically performed in synchronization with the AD converter.
  12	FIX_CLED	CLED Shift Register Latch ※CLED: color LED Reflect the value of the shift register to the output
  13	OE_CLED	CLED Output Enable CLED output ON/OFF
  14	PWM_CLED	Adjust the brightness of the CLED with PWM (Pulse Wide Modulation) control Short to 13pin or 5V when not using PWM

  summary

  • SEL_SEN pin for SPI switching of sensor (AD converter) and CLED.
  • Set the ILED channel with ABC.
  • After CLED transfers data to the shift register, it is reflected in the output with a FIX_CLED pulse.
  • CLED ON can adjust the brightness with AND output of 13pin and 14pin and PWM of 14pin.

  Sensor sensitivity adjustment method

  ILEDandPhTrYou can adjust the sensitivity of the sensor by moving the black cover up and down, but
  please be careful as it may deviate from the optimum sensitivity.

  ※ILED: Infrared LED,  PhTr: Phototransistor

  Main board circuit diagram

  Sensor board circuit diagram

• 3

  Software and interface of the sensor

  SPI interface setting (AD converter/shift register）

  • SPI-MODE:0
  • CLOCK：2MHz ※
  • One cycle (time interval between accesses to the same ILED) is 1.2mS or more

  AD converter reading procedure
  

  1. OE_CLED：LOW
  2. A,B,C      ：Sensor channel setting
  3. SEL_SEN: HIGH Select sensor, do not select CLED

  
  4. OE_ILED：LOW ILED OFF  ※ ILED: Infrared LED
  5. SS          ：LOW
  6. SPI-read AD read value:vOff
  7. SS           ：HIGH

  
  8. OE_ILED：HIGH ILED ON
  9. SS           ：LOW
  10. SPI-read AD read value:from
  11. SS           ：HIGH
  12. Temporary sensor value:fromOn - fromOff Save in an array

  
  ※ The value obtained by subtracting the ambient brightness measured at startup from the temporary sensor value is the sensor value.

                                                             Logic analyzer sensor reading diagram

  Read code of AD converter (Arduino C++)
  

  8 sensor readings

  void Sensor::setAd(bool bInit) {// bInit:add val to adAryInit[]
      for (int col = 0; col < COL_LEN; col++) {// COL_LEN：8
          setCol(col, bInit);    // *** sensing ***
      }
      if (!bInit)                // *** set CLED ***
          cled.set(val);        // sensor-data, indicator
  }

  Reading of a single sensor

  void Sensor::setCol(int col, bool bInit) {
      int ledSta = digitalRead(OE_CLED);
      digitalWrite(OE_CLED, LOW);
      out3bit(abc, col);
      digitalWrite(SEL_SEN, HIGH);
      digitalWrite(OE_ILED, LOW);   // ILED-OFF
      int vOff =getAdc(col);        // *** read ADC ***
      digitalWrite(OE_ILED, HIGH);  // ILED-ON
      int ofOn =getAdc(col);        // *** read ADC ***
      digitalWrite(SEL_SEN, LOW);
      digitalWrite(OE_ILED, LOW);   // ILED-OFF
      digitalWrite(OE_CLED, ledSta);
      if (bInit)
          adAryInit[col] += vOn - vOff - (vOff >> 2) + (vOn >> 4);
      else
          adAry[col] = noMinus(vOn - vOff - (vOff >> 2) + (vOn >> 4)- adAryInit[col]);
      val[col] = ad2val(adAry[col]);    // adAryInit[col]: Ambient brightness measured at startup
  }
  
  unsigned int Sensor::getAdc(int col) {
      digitalWrite(SS, LOW);
      SPI.transfer(6 | (col >> 2));
      unsigned char r1 = SPI.transfer(col << 6);
      unsigned char r2 = SPI.transfer(0);
      digitalWrite(SS, HIGH);
      return ((r1 & 0x0f) << 8) + r2;
  }

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