28230 Parallax Inc, 28230 Datasheet - Page 8

• Manufacturer Part Number: 28230
• Description: MCU, MPU & DSP Development Tools Propeller Dev Board (MSR1)
• Manufacturer: Parallax Inc

Specifications of 28230

• Processor To Be Evaluated: P8X32A-Q44
• Interface Type: USB
• Dimensions: 77.5 cm x 102.9 cm x 13.4 cm
• Maximum Operating Temperature: + 70 C
• Operating Supply Voltage: 6.5 to 15 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Driving Brushed DC Motors
This section will guide you through connecting and testing DC Brushed Gear Motors. DC motors are by the
L6205 H-Bridge on the Propeller Robot Control Board. Understanding how to control this H-Bridge is the key
to controlling the direction, speed and duration that the motors are on or off.
Parallax has released a Propeller object called, “PWM_32” which makes it easy to drive servos as well as
control motors using pulse width modulation. This object can be used with the Propeller Robot Control
Board to drive the on-board H-Bridge, which in turn drives the DC motors. This object can be downloaded
from the Propeller object exchange listed in the Useful Websites section at the end of this document.
Testing the Motors
'' File: Left Motor Test.spin
CON
_xinfreq = 5_000_000
_clkmode = xtal1 + pll16x
PUB Main
'' File: Right Motor Test.spin
CON
_xinfreq = 5_000_000
_clkmode = xtal1 + pll16x
PUB Main
Copyright © Parallax Inc.
dira[27..24] := %1111
outa[25] := 1
waitcnt(clkfreq * 2 + cnt)
outa[25] := 0
waitcnt(clkfreq * 2 + cnt)
outa[24] := 1
waitcnt(clkfreq * 2 + cnt)
outa[24] := 0
repeat
dira[27..24] := %1111
outa[26] := 1
waitcnt(clkfreq * 2 + cnt)
outa[26] := 0
waitcnt(clkfreq * 2 + cnt)
outa[27] := 1
waitcnt(clkfreq * 2 + cnt)
outa[27] := 0
repeat
Load the programs Left Motor Test.spin and Right Motor Test.spin into the Propeller Tool.
Slide the power switch on the control board to the second position (POWER ON/MOTORS ON).
Select each program one at a time and download it to the Stingray robot by pressing the F10 key.
Observe the results. Each motor should rotate forward for two seconds, stop for 2 seconds and
rotate reverse for 2 seconds.
Propeller Robot Control Board (#28230)
' External Crystal Frequency
' Enabled External Crystal and PLL X16
' Set P24 Through P27 To Output
' Left Motor Forward
' 2 Second Pause
' Left Motor Stop
' 2 Second Pause
' Left Motor Reverse
' 2 Second Pause
' Left Motor Stop
' External Crystal Frequency
' Enabled External Crystal and PLL X16
' Set P24 Through P27 To Output
' Right Motor Forward
' 2 Second Pause
' Right Motor Stop
' 2 Second Pause
' Right Motor Reverse
' 2 Second Pause
' Right Motor Stop
v1.0 11/3/2009 Page 8 of 9