சுதர்சன் சாந்தியப்பன்

Looks like the faulty nouveau driver is creating the fault during boot up. Without nomodeset and/or acpi=off, booting leads to segmentation fault by the nouveau module. When I disable the nouveau module by blacklisting it under modprobe.d, I am able to boot up cleanly using the Intel Sandybridge Mobile graphics driver.  After updating the blacklist configuration, remember to run update-initramfs -u.

filename: /etc/modprobe.d/nvidia-nouveau

# disable nouveau driver
blacklist nouveau
options nouveau modeset=0

LM35 Temperature Sensor

The System.

The monitor.

The mixed water line:

The hot water line:

The cold water line:

monitor opened up:

the atmega8 microcontroller

the lcd unit:

theboard:

inside the monitor:

The AVR code.

const int COLD = 0, HOT = 1, MIXED = 2, CALIBRATE = 3;
const int PWMPORT = 5;

float SCALE = 5000.0/1024.0; // 10 bit resolution for ADC
const float LM35SCALE = 10; // 10mV per Centigrade

#include <LiquidCrystal.h>

LiquidCrystal lcd(13, 12, 11, 10, 9, 8 );

byte smiley[8] = {
  B00010,
  B00101,
  B00010,
  B00000,
  B00000,
  B00000,
  B00000,
};

float Calibrate( void )
{
  // write 5v to PWM port
  analogWrite(PWMPORT, 255);

  // read the 5v analog value in the calibrate port
  delay(500);
  int val = analogRead(CALIBRATE);

  // read again the 5v analog value in the calibrate port
  delay(100);
  val = analogRead(CALIBRATE);

  // whatever digital value we read is the range of output that we would get for 5v input.
  // so, set the scale appropriately.
  SCALE = 5000.0/(float)val;
  
  return SCALE;
}

void setup()
{
  pinMode(PWMPORT, OUTPUT);
  
  lcd.createChar(0, smiley);
  lcd.begin(16,2);
  
  lcd.setCursor(0,0);
  lcd.print(“Calibrating..”);
  float scale = Calibrate();
  lcd.setCursor(0,1);
  lcd.print(“Scale=”);
  lcd.print(scale);
  delay(1000);
}

int Temp( int inADC )
{
  float lm35volts = (float)inADC * SCALE;
  float temp = lm35volts/LM35SCALE;
  
  return (int)temp;
}

int ReadData( int port )
{
  int data = -1;
  for ( int i = 0; i < 3; ++i )
  {
    data = analogRead( port );
    delay(100);
  }
  
  return data;
}

void loop()
{
  int cold = ReadData( COLD );
  int hot = ReadData( HOT );
  int mixed= ReadData( MIXED );
  
  int cold_temp = Temp(cold);
  int hot_temp = Temp(hot);
  int mixed_temp = Temp(mixed);
  
  lcd.clear();

  lcd.print( “C=” );
  lcd.print( cold_temp );
  lcd.write(0);
  lcd.print(“C”);
  lcd.print( ” H=” );
  lcd.print( hot_temp );
  lcd.write(0);
  lcd.print(“C”);
  
  lcd.setCursor(0,1);
  lcd.print( “Mixed=” );
  lcd.print( mixed_temp );
  lcd.write(0);
  lcd.print(“C”);
  
  delay(1000);
}

hash = ( fpArray*2654404609 )>>12; // Calculate the hash and limit the value to 2^20 (1 Meg)

unsigned hash = fpArray * 2654404609;
hash = hash >> 12;

unsigned long hash = (unsigned long)fpArray * 2654404609;
hash = hash >> 12;
unsigned h2 = (unsigned)hash;

hash = ( fpArray*2654404609U )>>12; // Calculate the hash and limit the value to 2^20 (1 Meg)
(or)
const unsigned multipler = 2654404609; // here U suffix is not needed as the constant is explicitly made unsigned
hash = ( fpArray * multiplier ) >> 12;

    Now, the computation will happen with 32 bit numbers to get the expected outputs.

Lessons Learned here:

1. While using constants, beware of the upcasting and downcasting. So use proper suffixes like U, L, F etc.
2. Instead of using constants directly in expressions, use them as constant variables.
3. Be conscious about the compiler type and the assumptions made by the compiler in different build modes.

Removing the headlamp from Getz Prime is pretty trivial and requires just only one tool and probably 5 minutes of time.  Let’s see how to go about that.

1. The Headlamp Assembly: It appears very dull ey? Yes, I was going to remove it and replace the frontal glass.

2. The Tool: All the bolts that attach the assembly to the chassis are 10mm and you would need a bit rod for disassembling the headlamp unit.

3. Remove Bolts: Use the 10mm bit rod to remove the bolts.  Remove the first bolt visible from the top.

4. Remove the other 3 bolts visible from the front side.

5. Remove the hidden bolt.  Now that you have removed the front side 3 bolts, you will be able to pull that plastic to expose the hidden lamp assembly bolt fastened to the chassis.

6. Shake and pull the the headlamp assembly.  Remember to remove three wiring harnesses connected to the headlamp assembly; a) The Bulb supply b) Motor, Parking lamp, Main Bulb supply c)  Indicator supply.

That’s it.  It takes just 5 minutes and 1 tool to remove the head lamp assembly from Getz Prime.

This write up is taken from http://www.engineeringtoolbox.com/wire-gauges-d_419.html

The AWG table below is for a single, solid, round conductor. Because of the small gaps between the strands in a stranded wire, a stranded wire with the same current-carrying capacity and electrical resistance as a solid wire, always have a slightly larger overall diameter. The higher the number – the thinner the wire. Typical household wiring is AWG number 12 or 14. For telephone wires there are common with AWG 22, 24, or 26.

The higher the gauge number, the smaller the diameter, and the thinner the wire.  Because of less electrical resistance a thick wire will carry more current with less voltage drop than a thin wire. For a long distance it may be necessary to increase the wire diameter – reducing the gauge – to limit the voltage drop.