List of some common G-code commands used in the Marlin firmware for 3D printers

Mark E.

a more comprehensive list of some common G-code commands used in the Marlin firmware for 3D printers:

  • G0: Rapid positioning to a specified point.
  • G1: Linear movement to a specified point at a specified speed.
  • G2: Clockwise arc movement to a specified point.
  • G3: Counterclockwise arc movement to a specified point.
  • G4: Dwell, or delay, for a specified time.
  • G10: Set or retrieve tool offset.
  • G20: Set units to inches.
  • G21: Set units to millimeters.
  • G28: Home all axes (move to the origin).
  • G29: Auto bed leveling.
  • G30: Single Z probe.
  • G31: Set or retrieve Z probe offset.
  • G32: Bed leveling.
  • G33: Calibrate delta printer.
  • G90: Set absolute positioning mode.
  • G91: Set relative positioning mode.
  • G92: Set current position to specified values.
  • M0: Stop or pause the printer.
  • M1: Sleep or standby mode.
  • M18: Disable all stepper motors.
  • M20: List files on the SD card.
  • M21: Initialize the SD card.
  • M22: Release the SD card.
  • M23: Select file on the SD card.
  • M24: Start/resume SD print.
  • M25: Pause SD print.
  • M26: Set SD position.
  • M27: Report SD print status.
  • M28: Begin write to SD card.
  • M29: End write to SD card.
  • M30: Delete file from SD card.
  • M32: Start SD print from a file with metadata.
  • M42: Control an output pin.
  • M84: Disable motors (for power saving).
  • M104: Set extruder temperature.
  • M106: Fan on.
  • M107: Fan off.
  • M109: Wait for extruder temperature to reach target.
  • M117: Display message on LCD.
  • M118: Send message to serial port.
  • M140: Set bed temperature.
  • M190: Wait for bed temperature to reach target.

Note that this is still not an exhaustive list, and some commands may be specific to certain printers or firmware versions. Always consult the documentation for your particular printer and firmware to learn more about the available commands and their syntax.

PHP code for color correction in photography

Mark E. 
<?php

// define image file path
$imagePath = 'path/to/image.jpg';

// create image resource
$image = imagecreatefromjpeg($imagePath);

// get image dimensions
$imageWidth = imagesx($image);
$imageHeight = imagesy($image);

// iterate through each pixel in the image
for ($x = 0; $x < $imageWidth; $x++) {
    for ($y = 0; $y < $imageHeight; $y++) {

        // get the color of the pixel
        $rgb = imagecolorat($image, $x, $y);

        // extract the red, green, and blue components
        $red = ($rgb >> 16) & 0xFF;
        $green = ($rgb >> 8) & 0xFF;
        $blue = $rgb & 0xFF;

        // adjust the color levels as needed
        $red = $red * 1.2;
        $green = $green * 0.9;
        $blue = $blue * 1.1;

        // make sure the color levels are within the 0-255 range
        $red = max(0, min(255, $red));
        $green = max(0, min(255, $green));
        $blue = max(0, min(255, $blue));

        // set the new color of the pixel
        $newRgb = ($red << 16) | ($green << 8) | $blue;
        imagesetpixel($image, $x, $y, $newRgb);
    }
}

// output the corrected image to the browser or save to a file
header('Content-Type: image/jpeg');
imagejpeg($image);

// clean up
imagedestroy($image);

?>

This code reads in an image file, creates an image resource using imagecreatefromjpeg(), and then loops through each pixel in the image using nested for loops. For each pixel, the code extracts the red, green, and blue components of the color using bit shifting and masking, and then adjusts the color levels as needed. In this example, the red level is increased by 20%, the green level is decreased by 10%, and the blue level is increased by 10%. The code then sets the new color of the pixel using imagesetpixel(). Finally, the corrected image is output to the browser or saved to a file using imagejpeg(), and the image resource is destroyed using imagedestroy().

PHP code for a 4-band resistor color code calculator

Mark E. 
<!DOCTYPE html>
<html>
<head>
	<title>4-Band Resistor Color Code Calculator</title>
</head>
<body>
	<h1>4-Band Resistor Color Code Calculator</h1>
	<form method="post">
		<p>
			<label for="band1">Band 1:</label>
			<input type="text" name="band1" id="band1">
		</p>
		<p>
			<label for="band2">Band 2:</label>
			<input type="text" name="band2" id="band2">
		</p>
		<p>
			<label for="band3">Multiplier:</label>
			<input type="text" name="band3" id="band3">
		</p>
		<p>
			<label for="band4">Tolerance:</label>
			<input type="text" name="band4" id="band4">
		</p>
		<p>
			<input type="submit" name="submit" value="Calculate Resistance">
		</p>
	</form>
	<?php
		// Define the color code array
		$color_codes = array(
			'black' => 0,
			'brown' => 1,
			'red' => 2,
			'orange' => 3,
			'yellow' => 4,
			'green' => 5,
			'blue' => 6,
			'violet' => 7,
			'gray' => 8,
			'white' => 9
		);

		// Check if the form has been submitted
		if (isset($_POST['submit'])) {
			// Get user input for resistor colors
			$band1 = strtolower(trim($_POST['band1']));
			$band2 = strtolower(trim($_POST['band2']));
			$band3 = strtolower(trim($_POST['band3']));
			$band4 = strtolower(trim($_POST['band4']));

			// Calculate resistance value
			$resistance = ($color_codes[$band1] * 10 + $color_codes[$band2]) * pow(10, $color_codes[$band3]);

			// Determine the tolerance value
			switch ($band4) {
				case 'gold':
					$tolerance = 5;
					break;
				case 'silver':
					$tolerance = 10;
					break;
				default:
					$tolerance = 20;
			}

			// Print the result
			echo "<p>The resistance value is: " . $resistance . " ohms +/- " . $tolerance . "%</p>";
		}
	?>
</body>
</html>

This code uses a form to get user input for the resistor colors, and then uses PHP to calculate the resistance value and the tolerance value based on the fourth band. The switch statement is used to determine the tolerance value based on the color of the fourth band (gold = 5%, silver = 10%, other colors = 20%). The calculated resistance value and the tolerance value are then displayed using the echo statement.

JavaScript code to calculate the resistance value of a resistor based on its color bands

Mark E.

Here's an example JavaScript code to calculate the resistance value of a resistor based on its color bands:

const colorCodes = {
  'black': 0,
  'brown': 1,
  'red': 2,
  'orange': 3,
  'yellow': 4,
  'green': 5,
  'blue': 6,
  'violet': 7,
  'gray': 8,
  'white': 9
};

const firstBand = 'brown'; // replace with the actual color of the first band
const secondBand = 'black'; // replace with the actual color of the second band
const thirdBand = 'red'; // replace with the actual color of the third band

const multiplier = 1;
const tolerance = 0.05;

const firstDigit = colorCodes[firstBand];
const secondDigit = colorCodes[secondBand];
const thirdDigit = colorCodes[thirdBand];

const ohms = (firstDigit * 10 + secondDigit) * multiplier;
const ohmsString = ohms.toFixed(2);

console.log(`Resistance value: ${ohmsString} ohms (+/-${tolerance})`);
- All From ChatGPT
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