DM163045 Microchip Technology, DM163045 Datasheet - Page 62

• Manufacturer Part Number: DM163045
• Description: PICDEM Lab Development Kit (with PICkit 3) General Purpose
• Manufacturer: Microchip Technology
• Series: PICDEM™r
• Type: MCUr

Specifications of DM163045

• Contents: Board, PIC kit 3
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: PIC Micro® MCU

PICDEM
DS41369A-page 58
TM
3. All remaining code from the previous lab is unchanged. Compile the project.
3.4.6.4
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
3.4.7.1
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
2. PORTA Weak Pull-Up Register: WPUA (Register 4-5 in Section 4 of the
3.4.7.2
This lab expands on the previous lab by adding weak pull-ups to remove the 10 K
used previously to tie RA2 pin to V
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
• Enable the PORTA/PORTB Pull-up Enable bit (RABPU) in the OPTION register
3.4.7.3
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
Lab Development Board User’s Guide
- Enables PORTA/PORTB weak pull-ups to be used on the PIC16F690.
- Selects which PORTA pins will have weak pull-ups enabled.
WPUA2 in the WPUA: PORTA Register.
by clearing it.
There should be no errors.
Sheet)
PIC16F690 Data Sheet)
from the previous lab.
TESTING THE APPLICATION
Lab 8: Using Weak Pull-Ups
NEW REGISTERS USED IN THIS LAB
OVERVIEW
PROCEDURE
DD
. Each of the PORTA pins (except RA3) and
© 2009 Microchip Technology Inc.
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