122-28176 Parallax Inc, 122-28176 Datasheet - Page 174

• Manufacturer Part Number: 122-28176
• Description: GUIDE STUDENT PROCESS CONTROL
• Manufacturer: Parallax Inc

Specifications of 122-28176

• Accessory Type: Manual
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Propeller Education (PE) Kit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Additional Parts Required
(2) 10 kΩ Resistors
(1) 4.7 kΩ Resistor
(2) 1 kΩ Resistors
Now how much does voltage change for each increment of PWM value? With a gain of
2, each increment is 0.0196 V x 2 or 0.0392 V. However, since the total output swing is
now 10 V instead of 5 V, the %Resolution is:
The %Resolution has not changed, which makes sense since the number of possible steps
(255) has not changed.
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Reconfigure the op-amp as shown in Figure 5-19. Set the 4.7 kΩ resistor aside
Add R
Save PwmFiltering.bs2 under a new name: ModPwmFiltering.bs2.
Change 0.0196 to 0.0392 in the following line of code
DEBUG DEC ADC_DataIn ,",",
"[",DEC ADC_DATAIn,",*,0.0392]",CR
This will calculate voltage based on a 10 volt maximum (10 / 255 = 0.0392).
Download your modified program.
Run the StampPlot macro sic_pc_pwm_filtering.spm.
Adjust the Y-Axis to monitor 0 – 10.
Measure the output voltage for various values of PWM.
0.0392 V / 10 V x 100% = 0.392 %
for the moment.
sensed voltage by 2 so that voltages over 5 V do not damage the ADC.
d1
and R
d2
for the ADC input. These act as a voltage divider to cut the