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Using the Port B Interrupt on Change as an External Interrupt

From Microchip Technology, Inc.
 

 
The PICmicro? families of RISC microcontrollers aredesigned to provide advanced performance and a cost-effective solution for a variety of applications. To address these applications, there is the PIC16CXXX microcontroller family of products. This family has numerous peripheral and special features to better address user applications. The feature this application note will focus on is the Interrupt on Change of the PORTB pins. This ?interrupt on change? is triggered when any of the RB7:RB4 pins, configured as an input, changes level. When this interrupt is used in conjunction with the software programmable weak internal pull-ups, a direct interface to a keypad is possible. This is shown in application note AN552, Implementing Wake-up on Key Stroke. Another way to use the ?interrupt on change? feature would be as additional external interrupt sources. This allows PIC16CXXX devices to support multiple external interrupts, in addition to the built-in external interrupt on the INT pin. This application note will discuss some of the issues in using PORTB as additional external interrupt pins, and will show some examples. These examples can be eas-ily modified to suit your particular needs.
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Microchip's PIC16CXXX microcontroller family are ideally suited to directly interface to a keypad. The high 4-bits of PORTB (RB7:RB4) have internal pull-ups and can trigger a ?change on state?... (Read More)
AN576 Techniques to Disable Global Interrupts ing this instruction, the program would complete execu- tion of this instruction, and then immediately branch to Author: Mark Palmer the user's interrupt... (Read More)
AN1081 Interfacing a 4x4 Matrix Keypad with an 8-Bit GPIO Expander * I/O Direction Register (IODIR): The IODIR Author: Mike Curran register controls the direction of the port pins. A Microchip... (Read More)
This application note describes a unique method for implementing interrupts in software on the PIC16C5X series of microcontrollers. This method takes advantage of the PIC16C5X?s architecture which... (Read More)
This chapter discusses interrupts, which are of critical importance when implementing efficient input/output operations for microcontroller applications. Topics include interrupt fundamentals, PIC18... (Read More)
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