Radio Shack Mobile Robot manual Steering Motor

Drive Motor and Encoder continued

The previous subroutine will START the drive motor. You can monitor the progress of the drive wheel by reading the encoder counter from the coprocessor. Here is example code that will read the encoder.

ec var word	'Encoder		count.
serout net,baud,["!1E1"]	'Ask	for	encoder count.
serin net,baud,[hex4, ec]	'Get	encoder count into ec.

You can use this code within a loop to wait until the desired distance is completed. Put a 100 ms delay between reads using a pause 100 command.

Steering Motor

The steering is an RC (remote control) style servo motor that is commonly used on model race cars and airplanes. The coprocessor can control 4 RC servo motors - #1 is used for steering. When the Basic Stamp II needs to control an RC servo motor, it simply sends a command to the coprocessor which han- dles the task. This frees up the Basic Stamp II for other tasks.

Here is a subroutine that can be used to control all 4 RC servo motors including the steering motor #1. Study the WANDER and TEST programs for additional insight.

'Constants and Variables.
net con 8		'coprocessor	network pin.
baud con	396	'coprocessor	baud rate.
position	var byte	'Position of	motor.
motor var byte		'Motor #.

'Subroutine	to control RC servo motors.
'Motor # 1-4.
'Position =	1-255, 0=off, 128=center.
'The servo is moved to the desired position for 500 ms
'then turned off to conserve power.
'
rcservo:
serout	net,baud,["!1R", dec1 motor, hex2 position] 'Move Motor.
serin net,baud,[charn]		'Get A.
pause 500		'Wait for servo to turn.
serout	net,baud,["!1R", dec1 motor, "00"]		'Motor off.
serin net,baud,[charn]		'Get A.
return

If you need your RC servo motor to resist movement after it has turned to the desired position, don’t turn

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