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Topic: Optical Mouse Sensor varys wildly depending on speed (Read 92 times) previous topic - next topic

obucklin

Hi,

I'm trying to use an optical mouse sensor ADNS-9800 to monitor the extrusion rate of clay coming out of a pug mill. I will use this extrusion rate to control the speed of cutting wires that cut custom parametric bricks.

I have the sensor giving me x and y data, which I cumulatively add and then use pythagorean theorem to get a total distance. The problem is that my readings depend heavily on the rate of motion. If I move the sensor 5cm in 1 second, the readings are around 1000 for total distance, but if i move it the same distance in 5 seconds, the reading is around 2500.

this is my code:

Code: [Select]

#include <SPI.h>
#include <avr/pgmspace.h>

// Registers
#define REG_Product_ID                           0x00
#define REG_Revision_ID                          0x01
#define REG_Motion                               0x02
#define REG_Delta_X_L                            0x03
#define REG_Delta_X_H                            0x04
#define REG_Delta_Y_L                            0x05
#define REG_Delta_Y_H                            0x06
#define REG_SQUAL                                0x07
#define REG_Pixel_Sum                            0x08
#define REG_Maximum_Pixel                        0x09
#define REG_Minimum_Pixel                        0x0a
#define REG_Shutter_Lower                        0x0b
#define REG_Shutter_Upper                        0x0c
#define REG_Frame_Period_Lower                   0x0d
#define REG_Frame_Period_Upper                   0x0e
#define REG_Configuration_I                      0x0f
#define REG_Configuration_II                     0x10
#define REG_Frame_Capture                        0x12
#define REG_SROM_Enable                          0x13
#define REG_Run_Downshift                        0x14
#define REG_Rest1_Rate                           0x15
#define REG_Rest1_Downshift                      0x16
#define REG_Rest2_Rate                           0x17
#define REG_Rest2_Downshift                      0x18
#define REG_Rest3_Rate                           0x19
#define REG_Frame_Period_Max_Bound_Lower         0x1a
#define REG_Frame_Period_Max_Bound_Upper         0x1b
#define REG_Frame_Period_Min_Bound_Lower         0x1c
#define REG_Frame_Period_Min_Bound_Upper         0x1d
#define REG_Shutter_Max_Bound_Lower              0x1e
#define REG_Shutter_Max_Bound_Upper              0x1f
#define REG_LASER_CTRL0                          0x20
#define REG_Observation                          0x24
#define REG_Data_Out_Lower                       0x25
#define REG_Data_Out_Upper                       0x26
#define REG_SROM_ID                              0x2a
#define REG_Lift_Detection_Thr                   0x2e
#define REG_Configuration_V                      0x2f
#define REG_Configuration_IV                     0x39
#define REG_Power_Up_Reset                       0x3a
#define REG_Shutdown                             0x3b
#define REG_Inverse_Product_ID                   0x3f
#define REG_Motion_Burst                         0x50
#define REG_SROM_Load_Burst                      0x62
#define REG_Pixel_Burst                          0x64

byte initComplete = 0;
byte testctr = 0;
unsigned long currTime;
unsigned long timer;
unsigned long pollTimer;
volatile int xydat[2];
volatile byte movementflag = 0;
const int ncs = 10;
int long x = 0;
int long y = 0;

extern const unsigned short firmware_length;
extern const unsigned char firmware_data[];

void setup() {
  Serial.begin(9600);

  pinMode (ncs, OUTPUT);

  //attachInterrupt(0, UpdatePointer, FALLING);

  SPI.begin();
  SPI.setDataMode(SPI_MODE3);
  SPI.setBitOrder(MSBFIRST);
  SPI.setClockDivider(8);

  performStartup();
  Serial.println("ADNS9800testPolling");
  dispRegisters();
  delay(5000);
  initComplete = 9;

}

void adns_com_begin() {
  digitalWrite(ncs, LOW);
}

void adns_com_end() {
  digitalWrite(ncs, HIGH);
}

byte adns_read_reg(byte reg_addr) {
  adns_com_begin();

  // send adress of the register, with MSBit = 0 to indicate it's a read
  SPI.transfer(reg_addr & 0x7f );
  delayMicroseconds(100); // tSRAD
  // read data
  byte data = SPI.transfer(0);

  delayMicroseconds(1); // tSCLK-NCS for read operation is 120ns
  adns_com_end();
  delayMicroseconds(19); //  tSRW/tSRR (=20us) minus tSCLK-NCS

  return data;
}

void adns_write_reg(byte reg_addr, byte data) {
  adns_com_begin();

  //send adress of the register, with MSBit = 1 to indicate it's a write
  SPI.transfer(reg_addr | 0x80 );
  //sent data
  SPI.transfer(data);

  delayMicroseconds(20); // tSCLK-NCS for write operation
  adns_com_end();
  delayMicroseconds(100); // tSWW/tSWR (=120us) minus tSCLK-NCS. Could be shortened, but is looks like a safe lower bound
}

void adns_upload_firmware() {
  // send the firmware to the chip, cf p.18 of the datasheet
  Serial.println("Uploading firmware...");
  // set the configuration_IV register in 3k firmware mode
  adns_write_reg(REG_Configuration_IV, 0x02); // bit 1 = 1 for 3k mode, other bits are reserved

  // write 0x1d in SROM_enable reg for initializing
  adns_write_reg(REG_SROM_Enable, 0x1d);

  // wait for more than one frame period
  delay(10); // assume that the frame rate is as low as 100fps... even if it should never be that low

  // write 0x18 to SROM_enable to start SROM download
  adns_write_reg(REG_SROM_Enable, 0x18);

  // write the SROM file (=firmware data)
  adns_com_begin();
  SPI.transfer(REG_SROM_Load_Burst | 0x80); // write burst destination adress
  delayMicroseconds(15);

  // send all bytes of the firmware
  unsigned char c;
  for (int i = 0; i < firmware_length; i++) {
    c = (unsigned char)pgm_read_byte(firmware_data + i);
    SPI.transfer(c);
    delayMicroseconds(15);
  }
  adns_com_end();
}


void performStartup(void) {
  adns_com_end(); // ensure that the serial port is reset
  adns_com_begin(); // ensure that the serial port is reset
  adns_com_end(); // ensure that the serial port is reset
  adns_write_reg(REG_Power_Up_Reset, 0x5a); // force reset
  delay(50); // wait for it to reboot
  // read registers 0x02 to 0x06 (and discard the data)
  adns_read_reg(REG_Motion);
  adns_read_reg(REG_Delta_X_L);
  adns_read_reg(REG_Delta_X_H);
  adns_read_reg(REG_Delta_Y_L);
  adns_read_reg(REG_Delta_Y_H);
  // upload the firmware
  adns_upload_firmware();
  delay(10);
  //enable laser(bit 0 = 0b), in normal mode (bits 3,2,1 = 000b)
  // reading the actual value of the register is important because the real
  // default value is different from what is said in the datasheet, and if you
  // change the reserved bytes (like by writing 0x00...) it would not work.
  byte laser_ctrl0 = adns_read_reg(REG_LASER_CTRL0);
  adns_write_reg(REG_LASER_CTRL0, laser_ctrl0 & 0xf0 );

  delay(1);

  Serial.println("Optical Chip Initialized");
}

void UpdatePointer(void) {
  if (initComplete == 9) {

    digitalWrite(ncs, LOW);
    xydat[0] = (int)adns_read_reg(REG_Delta_X_L);
    xydat[1] = (int)adns_read_reg(REG_Delta_Y_L);
    digitalWrite(ncs, HIGH);

    //movementflag=1;
  }
}

void dispRegisters(void) {
  int oreg[7] = {
    0x00, 0x3F, 0x2A, 0x02
  };
  char* oregname[] = {
    "Product_ID", "Inverse_Product_ID", "SROM_Version", "Motion"
  };
  byte regres;

  digitalWrite(ncs, LOW);

  int rctr = 0;
  for (rctr = 0; rctr < 4; rctr++) {
    SPI.transfer(oreg[rctr]);
    delay(1);
    Serial.println("---");
    Serial.println(oregname[rctr]);
    Serial.println(oreg[rctr], HEX);
    regres = SPI.transfer(0);
    Serial.println(regres, BIN);
    Serial.println(regres, HEX);
    delay(1);
  }
  digitalWrite(ncs, HIGH);
}


int convTwosComp(int b) {
  //Convert from 2's complement
  if (b & 0x80) {
    b = -1 * ((b ^ 0xff) + 1);
  }
  return b;
}

void loop() {

  currTime = millis();

  if (currTime > timer) {
    Serial.println(testctr++);
    timer = currTime + 5000;
    x = 0;
    y = 0;
  }

  if (currTime > pollTimer) {
    UpdatePointer();
    xydat[0] = convTwosComp(xydat[0]);
    xydat[1] = convTwosComp(xydat[1]);
    if (xydat[0] != 0 || xydat[1] != 0) {
      x = x + abs(xydat[0]);
      y = y + abs(xydat[1]);
      float Zpos = sqrt(x * x + y * y);
      Serial.print("x = ");
      Serial.print(x);
      Serial.print(" | ");
      Serial.print("y = ");
      Serial.println(y);
      Serial.print(" | ");
      Serial.print("dist = ");
      Serial.println(Zpos);
    }
    pollTimer = currTime + 1;
  }
}



Is there something in the code that could be causing this, or is it an inherent problem with optical mouse sensors?

thanks!

jremington

Serial.print is very slow. Trying increasing the baud rate.

gpsmikey

In a quick scan of the data sheet, I didn't see much, but this one line up at the top made me suspicious where it says "High   speed   motion   detection   up   to   150   ips   and   acceleration up to 30 g"  - typically, acceleration, on things I have seen are used to modify the "motion" where moving it fast gives what you were seeing with a larger number of counts.
mikey
-- you can't have too many gadgets or too much disk space !
old engineering saying: 1+1 = 3 for sufficiently large values of 1 or small values of 3

obucklin

typically, acceleration, on things I have seen are used to modify the "motion" where moving it fast gives what you were seeing with a larger number of counts.
It is actually the inverse, fast motion results in lower count.

Serial.print is very slow. Trying increasing the baud rate.
I will try this, see how it goes... ultimately, I won't need a serial print at all, I'm just using it to test the code.

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