Servo - May 2009

The following code group sets the CMU-01 camera’s internal registers. We are setting the lighting for fluorescent lights, Color Mode; auto white balance on. The white balance command takes approximately five seconds to adjust.

SerOut2 tx, 6, [“CR 45 7 18 44
 19 33”, 13]
GoSub ack
LCDOut “Color & AE on”
LCDOut 254, 192, “Wait 5 sec.”
Pause 5500

The following programming line commands the CMU-01 to turn off the Color Mode balance.

SerOut2 tx, 6, [“CR 45 7 18 40
 19 32”, 13]
GoSub ack

These next commands put the CMU-01 into Poll Mode (PM). This restricts the camera to sending a single packet of information when a processing function is called.

SerOut2 tx, 6, [“PM 1”, 13]
GoSub ack

The following lines put the CMU-01 into Raw serial transfer Mode (RM) where the “ACK\r and “NCK\r” confirmations are not sent after each command.

SerOut2 tx, 6, [“RM 1”, 13]
GoSub ack

This next code group sends the text message to the user via the LCD to place a target in front of the C-Bot. The user is given five seconds to accomplish this task.

LCDOut “Place Target”
LCDOut 254, 192, “5 sec.”
For x = 0 TO 10
SerOut2 tx, 6, [“L1 1”, 13]
Pause 250
SerOut2 tx, 6, [“L1 2”, 13]
Pause 250
Next x

In addition to the text message, the green LED blinks. In case the LCD is turned off to conserve power, the blinking LED also informs the user to place their target in front of the lens.

The next command tells the CMU-01 to Track the color found in the Window (TW). When this command is initiated, the CMU-01 shrinks its FOV window to 1/4 size of its standard resolution, captures the color in the window, then restores the window to its original size. To get an idea of the TW, look at Figure 12. The black section represents the 1/4 size capture color window.

SerOut2 tx, 6, ["TW", 13]

Wheel Construction

Here is a method to make simple servomotor wheels. We start with a 2” diameter hard wood dowel and cut 3/8” thick disks from it.

Figure A shows one wood disk, a paper guide (Figure B shows an enlarged version), and a push pin to mark the disk. The guide is aligned onto the wood disk. The push pin is pushed through the paper in the exact center of the disk as shown in Figure C.

Remove the paper and push pin from the wood disk. Next, align a servomotor horn onto it. Align the push pin hole to the center of the center screw hole on the servomotor horn. Attach the aligned servomotor horn to the wood disk using #4 x 1/4” long sheet metal screws (see Figure D).

FIGURE A. Wood disk, paper guide, and push pin.

FIGURE B. Paper guide.

Optional Steps

1) File flat the side of the servomotor horn that touches the wood disk.

2) After the servomotor horn is attached, remove the horn to drill a 1/4” hole through the center of the wood disk. Next, reattach the servomotor horn. The drilled hole allows you to attach the wheel to the servomotor using the horn screw.

FIGURE D. Finished wheel.

3) The bare wood wheels are a little slippery. So, I placed a small 1/4" wide black rubber band around the circumference of the wheels for traction. This worked out very well.