diff --git a/.gitignore b/.gitignore
index b34785a..a2dddcb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
-opt/
+opt/**/
 hex2bin
 
 # If you prefer the allow list template instead of the deny list, see community template:
diff --git a/README.md b/README.md
index 3347bd2..114c413 100644
--- a/README.md
+++ b/README.md
@@ -52,6 +52,8 @@ The tool supports two conversion modes:
 - `input_file`: Path to the input file (**required**)
 - `output_file`: Path to the output file (**optional**)
 - `mode`: Conversion mode (`hex2bin` or `bin2hex`, **optional**)
+- `--all`: (optional, for `bin2hex` only) Write all data, including 0xFF fill bytes, to the HEX file. By default, the tool writes only non-0xFF data (sparse HEX output).
+- `--record-bytes=N`: (optional, for `bin2hex` only) Set the number of bytes per HEX record (default: 16, e.g., 16 or 32).
 
 If `output_file` is not provided, it will be automatically determined from the input file name and mode.
 If `mode` is not provided, it will be inferred from the input file extension:
@@ -60,6 +62,30 @@ If `mode` is not provided, it will be inferred from the input file extension:
 
 If both `output_file` and `mode` are omitted, both will be inferred from the input file extension.
 
+### HEX Output Modes
+
+By default, when converting from binary to Intel HEX (`bin2hex`), the tool writes only non-0xFF data to the HEX file (sparse output). This matches the structure of reference HEX files and avoids unnecessary fill records.
+
+To force the tool to write all data (including 0xFF fill bytes) in the HEX file, use the `--all` flag:
+
+```bash
+hex2bin firmware.bin --all
+```
+
+To control the number of bytes per HEX record, use the `--record-bytes=N` flag (e.g., 16 or 32):
+
+```bash
+hex2bin firmware.bin --record-bytes=16
+```
+
+You can combine both flags:
+
+```bash
+hex2bin firmware.bin --all --record-bytes=16
+```
+
+This will produce a HEX file with records of the specified size (default is 16 bytes per record).
+
 ### Examples
 
 #### Minimal (auto mode and output):
@@ -107,3 +133,7 @@ hex2bin firmware.bin out.hex bin2hex
 ## License
 
 This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
+
+## Acknowledgement
+
+This project was generated using only AI via the Cursor app.
diff --git a/converter/converter.go b/converter/converter.go
index f0947ab..9fab3ab 100644
--- a/converter/converter.go
+++ b/converter/converter.go
@@ -46,50 +46,6 @@ func writeHexRecord(w io.Writer, recordType byte, address uint16, data []byte) e
 	return err
 }
 
-func BinToIntelHex(inputFile string, outputFile string) error {
-	// Read the binary input file
-	binData, err := os.ReadFile(inputFile)
-	if err != nil {
-		return fmt.Errorf("error reading input file: %v", err)
-	}
-
-	// Create output file
-	ofw, err := os.Create(outputFile)
-	if err != nil {
-		return fmt.Errorf("error creating output file: %v", err)
-	}
-	defer ofw.Close()
-
-	w := bufio.NewWriter(ofw)
-
-	// Write extended linear address record for the first segment
-	err = writeHexRecord(w, ExtLinearAddrRecord, 0x0000, []byte{0x00, 0x00})
-	if err != nil {
-		return fmt.Errorf("error writing extended address: %v", err)
-	}
-
-	// Write data records in 32-byte chunks
-	for i := 0; i < len(binData); i += 32 {
-		end := i + 32
-		if end > len(binData) {
-			end = len(binData)
-		}
-		chunk := binData[i:end]
-		err = writeHexRecord(w, DataRecord, uint16(i), chunk)
-		if err != nil {
-			return fmt.Errorf("error writing data chunk: %v", err)
-		}
-	}
-
-	// Write end of file record
-	err = writeHexRecord(w, EndOfFileRecord, 0x0000, nil)
-	if err != nil {
-		return fmt.Errorf("error writing EOF: %v", err)
-	}
-
-	return w.Flush()
-}
-
 func IntelHexToBin(inputFile string, outputFile string) error {
 	file, err := os.Open(inputFile)
 	if err != nil {
@@ -154,3 +110,74 @@ func IntelHexToBin(inputFile string, outputFile string) error {
 
 	return nil
 }
+
+// BinToIntelHexWithMode converts binary to Intel HEX, with a mode to write all data or only non-0xFF data
+// recordSize controls the number of bytes per HEX record (e.g., 16, 32)
+func BinToIntelHexWithMode(inputFile string, outputFile string, writeAll bool, recordSize int) error {
+	if recordSize <= 0 {
+		recordSize = 32
+	}
+	binData, err := os.ReadFile(inputFile)
+	if err != nil {
+		return fmt.Errorf("error reading input file: %v", err)
+	}
+
+	of, err := os.Create(outputFile)
+	if err != nil {
+		return fmt.Errorf("error creating output file: %v", err)
+	}
+	defer of.Close()
+
+	w := bufio.NewWriter(of)
+
+	// Write extended linear address record for the first segment
+	err = writeHexRecord(w, ExtLinearAddrRecord, 0x0000, []byte{0x00, 0x00})
+	if err != nil {
+		return fmt.Errorf("error writing extended address: %v", err)
+	}
+
+	if writeAll {
+		// Write all data in recordSize-byte chunks
+		for i := 0; i < len(binData); i += recordSize {
+			end := i + recordSize
+			if end > len(binData) {
+				end = len(binData)
+			}
+			chunk := binData[i:end]
+			err = writeHexRecord(w, DataRecord, uint16(i), chunk)
+			if err != nil {
+				return fmt.Errorf("error writing data chunk: %v", err)
+			}
+		}
+	} else {
+		// Improved sparse mode: write any chunk with at least one non-0xFF byte
+		for i := 0; i < len(binData); i += recordSize {
+			end := i + recordSize
+			if end > len(binData) {
+				end = len(binData)
+			}
+			chunk := binData[i:end]
+			write := false
+			for _, b := range chunk {
+				if b != 0xFF {
+					write = true
+					break
+				}
+			}
+			if write {
+				err = writeHexRecord(w, DataRecord, uint16(i), chunk)
+				if err != nil {
+					return fmt.Errorf("error writing data chunk: %v", err)
+				}
+			}
+		}
+	}
+
+	// Write end of file record
+	err = writeHexRecord(w, EndOfFileRecord, 0x0000, nil)
+	if err != nil {
+		return fmt.Errorf("error writing EOF: %v", err)
+	}
+
+	return w.Flush()
+}
diff --git a/main.go b/main.go
index 4c14310..a2bbe21 100644
--- a/main.go
+++ b/main.go
@@ -58,24 +58,47 @@ func getModeFromInputExt(inputFile string) (string, error) {
 }
 
 func main() {
-	if len(os.Args) < 2 || len(os.Args) > 4 {
+	writeAll := false
+	recordSize := 16
+	args := os.Args[1:]
+	// Check for --all and --record-bytes flags
+	for i := 0; i < len(args); {
+		if args[i] == "--all" {
+			writeAll = true
+			args = append(args[:i], args[i+1:]...)
+			continue
+		}
+		if strings.HasPrefix(args[i], "--record-bytes=") {
+			var n int
+			_, err := fmt.Sscanf(args[i], "--record-bytes=%d", &n)
+			if err == nil && n > 0 {
+				recordSize = n
+			}
+			args = append(args[:i], args[i+1:]...)
+			continue
+		}
+		i++
+	}
+
+	if len(args) < 1 || len(args) > 3 {
 		fmt.Printf("hex2bin v%s (built %s)\n", version, buildTime)
-		fmt.Println("Usage: hex2bin <input_file> [output_file] [mode]")
+		fmt.Println("Usage: hex2bin <input_file> [output_file] [mode] [--all] [--record-bytes=N]")
 		fmt.Println("Mode: 'bin2hex' for binary to Intel HEX conversion")
 		fmt.Println("      'hex2bin' for Intel HEX to binary conversion")
+		fmt.Println("      '--all' to write all data (no sparse HEX, for bin2hex mode)")
+		fmt.Println("      '--record-bytes=N' to set bytes per HEX record (default 16, e.g., 16 or 32)")
 		os.Exit(1)
 	}
 
-	inputFile := os.Args[1]
+	inputFile := args[0]
 	outputFile := ""
 	mode := ""
 
-	if len(os.Args) == 4 {
-		outputFile = os.Args[2]
-		mode = os.Args[3]
-	} else if len(os.Args) == 3 {
-		// Could be output file or mode
-		arg := os.Args[2]
+	if len(args) == 3 {
+		outputFile = args[1]
+		mode = args[2]
+	} else if len(args) == 2 {
+		arg := args[1]
 		if arg == "bin2hex" || arg == "hex2bin" {
 			mode = arg
 			var err error
@@ -94,7 +117,6 @@ func main() {
 			}
 		}
 	} else {
-		// Only input file provided
 		var err error
 		mode, err = getModeFromInputExt(inputFile)
 		if err != nil {
@@ -111,7 +133,7 @@ func main() {
 	var err error
 	switch mode {
 	case "bin2hex":
-		err = converter.BinToIntelHex(inputFile, outputFile)
+		err = converter.BinToIntelHexWithMode(inputFile, outputFile, writeAll, recordSize)
 	case "hex2bin":
 		err = converter.IntelHexToBin(inputFile, outputFile)
 	default: