Convert a PBM Bitmap for a Matrix Orbital LCD

You have a PBM icon and a Matrix Orbital LCD that wants its own binary format, and pbmtomatrixorbital is the bridge between the two.

Allow about ten minutes for a first conversion. You need a Linux shell, the netpbm package, and a readable PBM file. The examples below use Netpbm 11.5.2, provided here by Debian package version 2:11.05.02-1.1build1. The command itself does not open a serial port or upload anything: that part is a separate step, later.

1. Check the installed command

Confirm which executable your shell will run and record the local Netpbm version:

$ command -v pbmtomatrixorbital
/usr/bin/pbmtomatrixorbital
$ pbmtomatrixorbital --version
pbmtomatrixorbital: Using libnetpbm from Netpbm Version: Netpbm 11.5.2
...

The exact build details can vary. What matters is that the command exists and reports the expected Netpbm family; no elevated privileges are needed for this or for a normal conversion.

2. Confirm that the input is PBM

A PBM file describes a two-colour image. Raw PBM normally begins with P4; plain PBM begins with P1. Both are valid input. Inspect the file without changing it:

$ file /path/to/input.pbm
$ od -An -c -N 32 /path/to/input.pbm

• Do not trust the filename. A file called input.pbm might hold another format, and a real PBM image may have a different name.
• Check the magic number first. If the first bytes are not PBM, convert or export the source image to PBM with a suitable tool before going further.
• Know the raster. PBM uses one bit per pixel with black as a set bit, and its dimensions live in the header; the converter has no width or height option that can repair a header describing the wrong image.

3. Convert to a new output file

Pass the input pathname as the optional argument and redirect standard output to a new destination:

$ pbmtomatrixorbital /path/to/input.pbm > matrix-orbital-image.bin
$ printf 'exit=%s\n' "$?"
exit=0

A successful run normally prints nothing, because standard output is the converted image. The input is read, never modified. Keep the output name distinct from the input: redirecting a command's output over its own input can truncate the source before the converter has read it.

$ test ! -e matrix-orbital-image.bin && echo 'destination is unused'
destination is unused

If the destination already exists and matters, choose a new name or make a deliberate backup. Do not use sudo to bypass a careless pathname choice. If you accidentally create an incomplete output, remove only that output once you have checked the path; the original PBM should stay untouched.

4. Try a small, reproducible PBM

When diagnosing a real file, isolate the command from your image archive by feeding it a tiny plain PBM on standard input. This 8 by 4 test pattern is safe to reproduce:

$ printf 'P1\n# 8x4 test pattern\n8 4\n00000000\n00111100\n01000010\n01111110\n' \
    | pbmtomatrixorbital > /tmp/matrix-orbital-test.bin
$ wc -c /tmp/matrix-orbital-test.bin
10 /tmp/matrix-orbital-test.bin
$ xxd -g1 /tmp/matrix-orbital-test.bin
00000000: 08 04 00 0c 0a 0a 0a 0a 0c 00                    ..........

Two details are easy to miss here. With no pathname, the program reads standard input, and its output is binary. For this exact 8 by 4 input on Netpbm 11.5.2, the output is ten bytes: the dimensions followed by the converted raster. That byte sequence is a protocol-oriented result, not a portable image file for file or an image viewer.

5. Keep upload separate from conversion

The manual mentions mo-upload.pl as a program that can send the resulting image out through the serial port. That is a separate operation and no part of pbmtomatrixorbital. Inspect and keep the generated file first, then follow your Matrix Orbital device and uploader documentation for the port, baud rate, display model and upload procedure.

Common traps

• "command not found". Verify the package installation and PATH, then run command -v pbmtomatrixorbital again.
• Input open failure. Check ls -l /path/to/input.pbm, the pathname and read permission. Changing permissions or reaching for sudo should be a considered decision, not the first response.
• Unexpected output size or appearance. Inspect the PBM magic number and dimensions: a successful exit status only means the reader and writer completed, not that the source image was the one you intended.
• Help behaves unexpectedly. This command has no options defined specifically for it. It recognises common libnetpbm options, but on this installation --help tells you to use man pbmtomatrixorbital and returns status 1. Read the manual rather than guessing at a resize, device or serial option.

If you need to undo this guide's file operation, delete only the newly generated binary after verifying its pathname. The command never alters the PBM input or the LCD; a separate uploader may alter the display and needs its own recovery procedure.