AN552 - Microchip

AN552 Implementing Wake-up on Key Stroke

M Author: AN552 SUMMARY The PIC16CXXX is ideally suited to interface directly to a keypad application. Built in pull-up resistors and very low current consumption during sleep make it a very good candidate for battery powered remote operations and applications. Appendix A provides an example of the code. Performance: Code Size RAM Used 64 words 0 bytes Imp.

Features

for most of the time and wake-up only when a key is pressed. FIGURE 1: 4 KEY INTERFACE TO PIC16CXXX 4x1k LED1 LED2 LED3 LED4 SW1 SW2 SW3 SW4 4x100Ω RB0 RB1 RB2 RB3 RB4 RB5 RB6 RB7 PIC16CXXX IMPLEMENTATION Figure 1 depicts an application where four keys are connected to RB7:RB4. Internal pull-ups are used to maintain a high level on these inputs. In this example, LEDs are connected to RB3:RB0. When SW1 is pressed, LED1 is turned on and when SW2 is pressed, LED2 is turned on and so on. The PIC16CXXX is normally in SLEEP mode with the “change on state” interrupt enabled. When SW1 is pressed, .