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Scribbler Robot Review

Read the article, or skip to any of the following sections:

What is the Scribbler Robot?

How does the Scribbler work?

Scribbler Robot problems and recommendations


What is the Scribbler Robot?

The Scribbler Robot is an intelligent programmable robot for ages eight years and older. Rolling around on three wheels, it communicates via light and sound. It has light and infrared sensors, allowing it to find its way around objects, detect light sources, and follow lines drawn on the floor. It's called the "Scribbler" because it can also draw patterns and lines as it moves. The picture below is the Scribbler, with a leatherman thrown in for size determination:

This is a picture facing the front of the Scribbler. The three large holes in the center are the light detectors. The two holes nearer the front are infrared emitters. The center front hole is the infrared detector.

In the picture below, we're looking at the rear of the unit. The center top hole is called the "Pen Port", enabling the robot to "scribble": Place a marker in that hole, and the marker will touch the ground on the other side, thus drawing a line as the robot moves. The grilled hole below that is the speaker. Below the "Scribbler Robot" logo we have 4 LED lights, used for communication and status. Below the LEDs, we have a 9-pin female serial connector - this "Programming Port" is what the unit uses to communicate with a computer for programming. To the left of the Programming Port is the red reset button. To the right of the Programming Port is the Scribbler's On / Off switch.

Now we see the bottom on the Scribbler Robot. The battery compartment dominates the lower half (the Scribbler requires 6 AA batteries, and rechargeables work fine). Above the center "Pen Port" we see the four infrared line sensors used for detecting lines on the ground as the unit moves.

When you order a Scribbler Robot, you get the following:

Scribbler Robot

Scribbler CD-ROM (includes the Scribbler communication and programming software, though newer versions may be available online).

Programming cable (this is a straight-through 9-pin serial cable)

The Scribbler Robot Start-up Guide (it's also available online)

Note: In order to program the Scribbler, your computer must have a 9-pin serial port available. If you don't have one, but have an available USB port, get a USB to Serial converter. That's what I ended up using. The picture below shows the Scribbler connected to my laptop via a USB to Serial converter.

How does the Scribbler work?

Put of the box, the Scribbler is ready to go. It has 7 demo modes. They are:

1) Light-seeking behavior - Follow a directional light source - the unit will move to follow the brightest light source in a room.

2) Object detection - The Scribbler will tell you (via tones and LEDs) when it sees something in front of it, and in what direction the thing lies.

3) Object avoidance - Drive around while avoiding objects.

4) Line sensor - Will tell you (via LEDs) when it passes over lines or barcodes.

5) Line following - Print or draw black lines on paper, and the Scribbler will follow them.

6) Scribble - Place a marker in the Pen Port, and the Scribbler will draw a figure-8 and a square on whatever surface you place it on.

7) "Ambulance" - The Scribbler will seemingly go crazy, blinking its lights and making a siren noise while driving around avoiding objects. Though the Scribbler is intended for ages 8 and up, I've found this mode, with all the sound and lights, is great for entertaining babies:

This is all dandy, and is a fun and easy way to show off what the Scribbler can do, but the really cool stuff is TELLING the Scribbler what to do. Programming.

GUI: The easiest way to program the Scribbler is to use the GUI interface. The Scribbler Program Maker gives us an intuitive way of graphically programming the Scribbler. The screen below is a screen shot of the program. You'll see programming options on the left, a "main menu" along the top, and the center portion is for the GUI program code itself. Those pictures tell the Scribbler what to do and when. I was able to figure out 90% of what everything did within a few minutes of playing around. When I needed help of clarification, I used the (very comprehensive) help text, available by clicking the question-mark icon in the upper-right.

I found the GUI software simple to use and easy to understand. I was able to create a custom program and run it on the Scribbler in just a few minutes.

The Scribbler Program Maker also allows you to reload the Scribbler's factory defaults (when you load your custom program, the 7 demo modes are erased. Use this to restore the original programming), monitor the Scribbler's sensors in real time, calibrate the Scribblers sensors, and view and edit the Scribbler program using PBASIC.

PBASIC: This is the actual programming language designed for the Scribbler and its "BASIC Stamp 2" brain. The PBASIC environment is more complex, as it assumes an understanding of reading and writing program code. If you find the GUI environment too limited or frustrating to work with, then move up to this next level to get more functionality and power: The BASIC Stamp Editor.

Hacking: For those interested in exploring the Scribbler, both in a programmatic and nuts-and-bolts level, I'm happy to say the unit is made with hackers in mind: The Scribbler schematics and electrical diagram are available online. You can download the full (Perl) source code to the GUI Scribbler Program Maker. And for those using PBASIC, you can download the 500+ PBASIC manual. Finally, let's crack open the Scribbler Robot itself. Here's what we see:

Taking a closer look at the circuit board, we see this.

The construction appears well-designed. It's robust and mostly solid-state. The moving parts (wheels, axles, motor mounts and motors) are easy to remove and repair. While looking at the top circuit board, we see a hacker port, used for adding additional functionality:

Here's the schematic:

For those interested, here are the functional program stats and limitations of the Scribbler's "BASIC Stamp 2" brain:

Processor speed: 20MHz
Execution speed: ~4000 instructions per second
RAM size: 32 Bytes (6 used for I/O, 26 are variable)
EEPROM program size: 2K Bytes, or ~500 instructions
I/O pins: 16 (+ 2 dedicated)
PBASIC commands: 42

Scribbler Robot problems and recommendations

Calibration: Be sure to calibrate the unit with the GUI "Scribbler Program Maker". Mine worked better at light detection and moving straight after I ran this tool. This is not a flaw in any sense of the word. Devices like this need to be calibrated, and kudos to the developers for giving us a tool to do so. But it's not explicitly recommended, which is why I'm mentioning it here.

Have a computer handy: Can you use the Scribbler without a computer? Yes, but you're missing out on most of the functionality. The demo modes are cool, but a lot of the fun is in programming it.

Batteries: You'll suck up batteries. Not because of battery-sucking design, but because you'll be playing with the Scribbler so often. Use rechargeable batteries. I used several flavors of Ni-MH (from 2000 to 2600 mAh), and they worked fine.

Software bugs: Be aware of two software bugs. You may or may not experience them, but I did:

1) When installing the CD versions of the BASIC Stamp Editor (the advanced programming tool), I get "Error 1303. The installer has insufficient privileges to access this directory: C:\Config.Msi." Just click "Retry" and the install should continue with no problem:

2) The Scribbler's Sensor Monitoring software (accessible through the Scribbler Program Maker 1.0 software), isn't available in the version on my CD. The button was, though. You'll see this when you click "Monitor the Scribbler's Sensors":

No problem, just go to the Scribbler website and download the latest version of the program. Install it, and see the new "Scribbler Sensor Observation Deck":

It gives a snazzy view of all the sensors and what they're currently detecting. However, I have problems when using this tool. After running it for a few minutes, experimenting with the sensors, this function has crashed my (Windows XP) computer multiple times. This has happened about 60% of the time, either when using the "Observation Deck" or immediately after closing it. I get a frustratingly generic Windows XP error log:

I'd recommend getting the (as of this writing) 1.0a upgrade, as upgrades are usually a good thing, but experiment with the "Scribbler Sensor Observation Deck", and if it crashes your PC, don't use it unless you really need to. And save anything you're doing beforehand.


The Scribbler Robot is the perfect entry-level robot for those interested in such things. I'm extremely impressed with it, not just in functionality but in the range of user experience levels the Scribbler supports. It's made for casual users (out of the box), intermediate users (GUI programming), advanced users (PBASIC) and programmers and hackers (hacker port, full schematics and source code online). There was a significant amount of effort expended to get it to that point, and it's evident and appreciated.

This is truly a robot I wish I had when I was younger. Both because it beats the pants off any equivalently-priced programmable robot kit, and because I had a lot of time back then. I don't have a lot of time now, and during the review I kept looking at the Scribbler longingly: I'd much rather play with it than write about it. It's a new and exiting toy, allowing users to understand a deep level of programming, problem solving and robotics interaction, and simultaneously have lots of fun (how many other devices can claim this?) I'd eagerly recommend the Scribbler Robot to anyone.

To purchase a Scribbler Robot, or for more information (including free software, documentation, Parallax-supported user forums, and BASIC stamp resources) visit the Scribbler Robot website.

If you want something more complex and advanced than the Scribbler, check out the Vex Robotics Design System.