2.2.6 LED & Buzzer ON on KEY press [intermittent buzzer ON]

Hello Readers:

I have started this blog to show you Embedded C programming for 8051 family microcontroller using KEIL compiler. The KISS philosophy is used to write this tutorial. What is KISS? Keep It Simple, Stupid!

2. Manipulating Port Pins

This section teaches you how to manipulate port pins bytewise and bitwise.

2.2 Bitwise [single bit]

Now we see how to control port pins bitwise.

2.2.6   LED & Buzzer ON on KEY press [intermittent  buzzer ON]

This program drives output device buzzer when KEY is pressed and thus shows how to manipulate single bit of microcontroller chip. Here Buzzer bit is configured as output pin and KEY bit as input pin. Since buzzers are frequently used in embedded systems to show the status of the system or alerting the user, this program is worth noted. In this program buzzer is generating intermittent sounds when key is pressed. It is necessary as embedded systems needs different tones for different tasks.

Start KEIL V4.01 and close projects, if any are open. Now start new project with Device -> Generic->8051 [all variants] for general 8051 family target chip. Add a new text file, name it Pgm_226.C and add it to above created project as a source file. It is time to add code to Pgm_226.C, so type below shown code in it.

 

Code explanation:

Line 08 & 07: Declaring 0^th & 1^st bit of Port 2 as Buzzer & KEY bits respectively.

Line 16: This statement makes KEY pin as input pin.

Line 17: This statement creates infinite loop.

Line 18: The if control structure checks whether KEY pin is NOT HIGH, and if yes i.e., LOW then calls Buzzer() function. Note that when KEY is pressed the pin voltage will be grounded.

Line 21: This Buzzer() function generates intermittent sound when KEY is pressed.

Note: you can change the MSDelay() parameters from 25 to anything and hear different tones at buzzer output.

Below is the flow chart diagram of program PGM_226.C.

After typing the code, press F7 or click Project->Build Target for building the source code. If there are no typical errors file will build successively and shows zero errors and zero warnings.

Now enter into debug mode by pressing Ctrl+F5 or click Debug->Start/Stop Debug Session menu. To get Port 2 tab click Peripherals->I/O Ports->Port 2 menu.

Run the program by pressing F5 or clicking Debug->Run. Since this needs user key press signal for simulation, you cannot simulate it fully. You can add this program file to PGM_224 project file, which is available in 2.2.4 section [or click here]. Copy the PGM_224 project folder and paste it once again and rename it as PGM_226. Now open PGM_226 project in KEIL V4.0 and remove the source file PGM_224.C and add this PGM_226.C file to it. Now compile the project and run the program in debug mode. For program verification steps please refer 2.2.4 section as they are same with slight change [instead of LED here you are driving Buzzer]. 

If you generate HEX file of this program, burn it into your target chip’s memory using suitable uploader and connecting switch and Buzzer to Port 2 pins you can hear intermittent buzzer sound when switch is pressed. To stop running the program press red ‘x’ mark icon or click Debug->Stop. 

To get back the compile mode press Ctrl+F5 or click Debug->Start/Stop Debug Session menu.   

<End of 2.2.6 LED & Buzzer ON on KEY press [intermittent  buzzer ON]>

...till next post bye-bye & take care.