ARM HOW-TO GUIDE Interfacing Buzzer with LPC2148 ARM

Transcription

1 ARM HOW-TO GUIDE Interfacing Buzzer with LPC2148 ARM

2 Contents at a Glance ARM7 LPC2148 Primer Board... 3 Buzzer... 3 Interfacing Buzzer... 4 Interfacing Buzzer with LPC Pin Assignment with LPC Circuit Diagram to Interface Buzzer with LPC Source Code... 6 C Program to generate sound in LPC2148 using Buzzer... 7 Testing the Buzzer with LPC General Information... 9

3 ARM7 LPC2148 Primer Board The ARM7 LPC2148 Primer board is specifically designed to help students to master the required skills in the area of embedded systems. The kit is designed in such way that all the possible features of the microcontroller will be easily used by the students. The kit supports in system programming (ISP) which is done through serial port. NXP s ARM7 (LPC2148), ARM Primer Kit is proposed to smooth the progress of developing and debugging of various designs encompassing of High speed 32-bit Microcontrollers. Buzzer Buzzer is an electrical device, which is similar to a bell that makes a buzzing noise and is used for signaling. Typical uses of buzzers and beepers include alarm devices, timers and confirmation of user input such as a mouse click or keystroke.

4 Interfacing Buzzer Fig. 1 shows how to interface the Buzzer to microcontroller. A piezoelectric element may be driven by an oscillating electronic circuit or other audio signal source, driven with a piezoelectric audio amplifier. Sounds commonly used to indicate that a button has been pressed are a click, a ring or a beep. When the input port pin from microcontroller is changed, the sound wave is changed in Buzzer. Fig. 1 Interfacing Buzzer to Microcontroller

5 Interfacing Buzzer with LPC2148 A small piezoelectric buzzer on the ARM2148 Primer Kit, by pulling pin P0.7 low, current will flow through the buzzer and a relatively sharp, single-tone frequency will be heard. The alternative PWM feature of pin P0.7 (the PWM2 signal) can be used to modulate the buzzer to oscillate around different frequencies. Then the volume of the sound will be changed by alternating the pulse width. The buzzer can be disconnected by removing jumper JP1, and this is also the default position for this jumper since the buzzer sound can be quite annoying if always left on. Pin Assignment with LPC2148 Buzzer Buzzer LPC2148 Buzzer Selection LS1 I/P P0.7 JP Enable Buzzer - Disable Buzzer

6 61 62 XTAL2 XTAL1 VREF VDD1 VDD2 VDD3 VDDA Circuit Diagram to Interface Buzzer with LPC V JP1 BZ 3V3 3V3 U16 R10 3K9 R9 3K9 1 Q1 BC847AL VSS1 VSS2 VSS3 VSS4 VSS5 VSSA LPC2148 P R11 10E 1 LS1 2 buzzer 12MHz C46 22pf X18 C47 22pf Source Code The Interfacing Buzzer with LPC2148 program is very simple and straight forward. We now want to generate a sound in LPC2148 Primer Board by using a buzzer. The C programs are developed in Keil software.

7 C Program to generate sound in LPC2148 using Buzzer *************************************************************************************** Title : Program to generate sound using Buzzer *************************************************************************************** #include <LPC214x.h> #include <stdio.h> #define BUZZ 7 void Delay(void); void Wait(void); void main() { PINSEL0 = 0x00; //Configure Port0.7 as GPIO IODIR0 = 3 << BUZZ; //Configure Port0.7 as O/P pin while(1) { IOSET0 = 1 << BUZZ; Delay(); IOCLR0 = 1 << BUZZ; Delay(); } } void Delay() { unsigned int i,j; for(i=0;i<1000;i++) for(j=0;j<700;j++); }

8 To compile the above C code you need the KEIL software. They must be properly set up and a project with correct settings must be created in order to compile the code. To compile the above code, the C file must be added to the project. In Keil, you want to develop or debug the project without any hardware setup. You must compile the code for generating HEX file. In debugging Mode, you want to check the port output without LPC2148 Primer Board. The Flash Magic software is used to download the hex file into your microcontroller IC LPC2148 through UART0. Testing the Buzzer with LPC2148 Give +3.3V power supply to LPC2148 Primer Board; the Buzzer is connected with LPC2148 Primer Board. When the program is downloading into LPC2148 in Primer Board, the Buzzer output is working that the Buzzer is creating some sound.

9 If you not getting any sound from Buzzer, then you just check the jumper connections & check the Buzzer is working or not. Otherwise you just check it with debugging mode in Keil. If you want to see more details about debugging just see the videos in below link. How to Create & Debug a Project in Keil. General Information For proper working use the components of exact values as shown in Circuit file. Wherever possible use new components. Solder everything in a clean way. A major problem arises due to improper soldering, solder jumps and loose joints. Use the exact value crystal shown in schematic. More instructions are available in following articles, User Manual of LPC2148 Primer Board. Tutorial of how to create & Debug a project in Keil.

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