Simple SD card checker for initial few GB of drive to do a basic check to see if a card is fake or not

sdcardchecker.ps1

# For Windows Powershell
# This program (created by ChatGPT) checks the integrity of an SD card by creating a large test file, copying it to a specified location, and comparing the two files.
# It prompts the user for the SD card drive letter and destination folder, and allows the user to create the destination folder if it doesn't exist.

# Prompt user for drive letter and destination folder
$driveLetter = Read-Host "Enter the drive letter of the SD card (e.g. E:)"
$destinationFolder = Read-Host "Enter the full path to copy the file to (e.g. C:\Users\YourName\Desktop)"
$testSizeGB = Read-Host "Enter test file size in GB (default is 8GB)"
if (-not $testSizeGB) { $testSizeGB = 8 }
[int]$testSizeGB = $testSizeGB
$blockCount = $testSizeGB * 1024  # 1MB blocks

# --- Validate SD card drive ---
if (-not (Test-Path "$driveLetter\")) {
    Write-Error "Drive $driveLetter not found or inaccessible."
    exit 1
}

# --- Validate destination folder ---
if (-not (Test-Path $destinationFolder)) {
    Write-Warning "Destination folder does not exist: $destinationFolder"
    $create = Read-Host "Would you like to create it? (Y/N)"
    if ($create -match '^[Yy]$') {
        try {
            New-Item -ItemType Directory -Path $destinationFolder -Force | Out-Null
            Write-Output "✅ Created destination folder."
        } catch {
            Write-Error "❌ Could not create the folder: $_"
            exit 1
        }
    } else {
        Write-Output "❌ Aborting. Destination folder must exist."
        exit 1
    }
}

# Set file paths
$sourcePath = Join-Path "$driveLetter\" "sdcard_testfile_${testSizeGB}gb.bin"
$destinationPath = Join-Path $destinationFolder "sdcard_testfile_${testSizeGB}gb_copy.bin"

Write-Output "Creating ${testSizeGB}GB file on $driveLetter..."
$buffer = New-Object byte[] (1MB)
$rnd = New-Object System.Random

# Write test file
[System.IO.File]::OpenWrite($sourcePath) | ForEach-Object {
    $i = 0
    while ($i -lt $blockCount) {
        $rnd.NextBytes($buffer)
        $_.Write($buffer, 0, $buffer.Length)
        $i++
        if ($i % 512 -eq 0) { Write-Progress -Activity "Writing..." -Status "$i MB written..." -PercentComplete ($i / $blockCount * 100) }
    }
    $_.Close()
}
Write-Output "✅ File created at $sourcePath."

# Copy to destination
Write-Output "Copying file to $destinationPath..."
Copy-Item -Path $sourcePath -Destination $destinationPath -Force

# Compare files
Write-Output "Comparing files..."
$compare = fc.exe /b $sourcePath $destinationPath

if ($LASTEXITCODE -eq 0) {
    Write-Output "✅ Files match: SD card passed the ${testSizeGB}GB integrity test."
} else {
    Write-Output "❌ Files do NOT match: Possible fake or faulty SD card."
}

# Clean up
Write-Output "Deleting test files..."
Remove-Item $sourcePath -Force
Remove-Item $destinationPath -Force

Write-Output "Done."