User manual
Table Of Contents
- Chapter 1. Overview
- 1.1 Introduction
- 1.2 Highlights
- 1.3 PICDEM™ Lab Development Kit Contents
- 1.4 PICDEM™ Lab Development Board Construction and Layout
- 1.5 Target Power
- 1.6 Connecting the PICkit™ 2 Programmer/Debugger
- 1.7 Solderless Prototyping Area Strip Configuration
- Chapter 2. Getting Started
- 2.1 Introduction
- 2.2 Prerequisites
- 2.3 The Software Control Loop
- 2.4 MPLAB® IDE Download Instructions
- 2.5 Installing the Included Lab Files
- Chapter 3. General Purpose Input/Output Labs
- 3.1 Introduction
- 3.2 General Purpose Input/Output Labs
- 3.3 GPIO Output Labs
- 3.3.1 Reference Documentation
- 3.3.2 Equipment Required for GPIO Output Labs
- 3.3.3 PICDEM Lab Development Board Setup for GPIO Output Labs
- Figure 3-1: PICDEM Lab Schematic for GPIO Output Labs
- 3.3.4 Lab 1: Light LEDs
- Figure 3-2: MAIN() Software Control Loop Flowchart for Lab 1
- Figure 3-3: Step One
- Figure 3-4: Step Two
- Figure 3-5: Step Three
- Figure 3-6: Step Four
- Figure 3-7: Summary
- Figure 3-8: Project Window
- Figure 3-9: PICkit 2 PROGRAMMER/DEBUGGER TOOLBAR
- Figure 3-10: Lab 1 LED Output
- 3.3.5 Lab 2: Flash LEDs (Delay Loop)
- Figure 3-11: Main() Software Control Loop Flowchart for Lab 2
- Figure 3-12: Timing() Delay Routine Flowchart for Lab 2
- 3.3.6 Lab 3: Simple Delays Using Timer0
- Equation 3-1: TMR0 Overflow Period using FOSC/4
- Equation 3-2: TMR0 Overflow Period when including the Prescaler
- Equation 3-3: Calculating a TMR0 PreLoad Value to generate a 10mS Overflow Period
- Figure 3-13: Delay_10mS() using Timer0
- Equation 3-4: Maximum TMR0 Overflow Period
- Figure 3-14: Delay_1S() using Timer0
- 3.3.7 Lab 4: Rotate LEDs
- Figure 3-15: Main() Software Control Loop Flowchart for Lab 4
- Figure 3-16: Decide() Flowchart for Lab 4
- Figure 3-17: Results of Do_Output()
- 3.4 GPIO Input Labs
- 3.4.1 Reference Documentation
- 3.4.2 Equipment Required for GPIO Input Labs
- 3.4.3 PICDEM Lab Development Board Setup for GPIO Input Labs
- Figure 3-18: PICDEM Lab Schematic for GPIO Input Labs
- 3.4.4 Lab 5: Adding a Push Button
- Figure 3-19: Main() Software Control Loop Flowchart for Lab 5
- Figure 3-20: Get_Inputs() Software Flowchart for Lab 5
- Figure 3-21: Delay_5mS() Software Flowchart for Lab 5
- Figure 3-22: Decide() Software FlowChart for Lab 5
- 3.4.5 Lab 6: Push Button Interrupt
- Figure 3-23: Main() Software Control Loop Flowchart for GPIO Lab 6
- Figure 3-24: pb_pressISR() for Lab 6 Showing Switch Debounce
- 3.4.6 Lab 7: Push Button Interrupt-on-Change
- Figure 3-25: pb_pressisr Flowchart for Lab 7
- 3.4.7 Lab 8: Using Weak Pull-Ups
- Chapter 4. Comparator Peripheral Labs
- 4.1 Introduction
- 4.2 Comparator Labs
- 4.2.1 Reference Documentation
- 4.2.2 Comparator Labs
- 4.2.3 Equipment Required
- 4.2.4 Lab 1: Simple Compare
- Figure 4-1: Schematic for Comparator Lab 1
- Figure 4-2: Main() software Control Loop Flowchart for Comparator Lab 1
- 4.2.5 Lab 2: Using the Comparator Voltage Reference
- Equation 4-1: CVref Output Voltage
- Equation 4-2: Calculating a 2.5V Internal Reference (Low-Range Method)
- Figure 4-3: Schematic for Comparator Lab 2
- 4.2.6 Lab 3: Higher Resolution Sensor Readings Using a Single Comparator
- Figure 4-4: Basic Relaxation Oscillator Circuit
- Figure 4-5: Schematic for Comparator Lab 3
- Figure 4-6: Main() software Control Loop Flowchart for Comparator Lab 3
- Figure 4-7: TMR0_ISR Flowchart for Comparator Lab 3
- Chapter 5. Analog-to-Digital Converter Peripheral Labs
- 5.1 Introduction
- 5.2 ADC Labs
- Figure 5-1: Schematic for ADC Lab 1
- Figure 5-2: Main() software Control Loop Flowchart for Comparator Lab 1
- Figure 5-3: Main() software Control Loop Flowchart for Comparator Lab 1
- Figure 5-4: ADC Result Bit Significance
- Figure 5-5: Schematic for ADC Lab 2
- Figure 5-6: Main() software Control Loop Flowchart for ADC Lab 2
- Appendix A. Schematic
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PICDEM
TM
Lab Development Board User’s Guide
DS41369A-page 58 © 2009 Microchip Technology Inc.
3. All remaining code from the previous lab is unchanged. Compile the project.
There should be no errors.
3.4.6.4 TESTING THE APPLICATION
Program the PIC16F690. The LEDs connected to PORTC should now flash sequen-
tially from left-to-right when the push button is released and flash from right-to-left when
the push button is pressed.
The solution for this project is located in the
C:\PICDEM_Lab\GPIO_Labs\GPIO_Lab7\solution directory.
3.4.7 Lab 8: Using Weak Pull-Ups
3.4.7.1 NEW REGISTERS USED IN THIS LAB
To configure the peripherals used in this lab, the following registers are used:
1. OPTION Register: OPTION (Register 2-2 in Section 2 of the PIC16F690 Data
Sheet)
- Enables PORTA/PORTB weak pull-ups to be used on the PIC16F690.
2. PORTA Weak Pull-Up Register: WPUA (Register 4-5 in Section 4 of the
PIC16F690 Data Sheet)
- Selects which PORTA pins will have weak pull-ups enabled.
3.4.7.2 OVERVIEW
This lab expands on the previous lab by adding weak pull-ups to remove the 10 K
Ω
used previously to tie RA2 pin to VDD. Each of the PORTA pins (except RA3) and
PORTB pins, has an individually configurable internal weak pull-up. Essentially, these
weak pull-ups perform the same task as the resistor connected to the RA2 pin and push
button as shown in Figure 3-12 only internal to the microcontroller. This feature can be
used to decrease component counts in the circuit.
Clearing the PORTA/PORTB Pull-up Enable bit, RABPU
, in the OPTION register will
enable weak pull-ups on any PORTA pin selected using the Weak Pull-Up PORTA
register (WPUA).
The only change needed to the PICDEM Lab Development Board Schematic shown in
Figure 3-18 is to remove the 10 KΩ resistor connected to both the push button and pin
RA2.
The Initialize() is all that needs to be changed in firmware by adding the following
configurations:
• Select RA2 to have a weak pull-up by setting the Weak Pull-Up Register bit
WPUA2 in the WPUA: PORTA Register.
• Enable the PORTA/PORTB Pull-up Enable bit (RABPU
) in the OPTION register
by clearing it.
3.4.7.3 PROCEDURE
Using the firmware developed in the previous lab, make the following changes:
1. Copy/paste the code in Example 3-28 into the Initialize() over the code
from the previous lab.