Latest revision as of 20:00, 3 September 2016

Light Emitting Diodes (LEDs) are simple and most commonly used electronic components to display the digital signal states. The LED emits light when current is passed through it. It could blow up if we pass more current, hence we put a current limiting resistor. Usually, 220, 470 and 1K ohm resistors are commonly used as limiting resistors. You can use any of these depending on the required brightness. Lets, start blinking with LEDs and then generate the different patterns using the available LEDs.

8051 Ports

The basic and important feature of any controllers is the number of GPIO's available for connecting the peripherals. 8051 has 32-gpio's grouped into 4-Ports namely P0-P3 as shown in the below table.

PORT	Number of Pins	Alternative Function
P0	8 (P0.0-P0.7)	AD0-AD7 (Address and Data bus)
P1	8 (P1.0-P1.7)	None
P2	8 (P2.0-P2.7)	A8-A15 (Higher Address Bus)
P3	8 (P3.0-P3.7)	UART, Interrupts, (T0/T1)Counters

As shown in the above table many I/O pins have multiple functions. If a pin is used for other function then it may not be used as a gpio.

Hardware Connections

Examples

Example 1

Program to demonstrate the LED blinking. LED's are connected to P2 as shown in the above image.
LEDs are turned ON by sending a high pulse (All Ones).
After some time the LEDs are turned OFF by sending the low pulse (All Zeros).

Example 2

In this example, we will see how to access a single port pin to blink the LED.

Demo

Downloads

Download the complete project folder from this link.

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 <br><br>
 ===Example 2===
-This is second approach in which FIOPIN register is used for both setting and clearing the PORT pins.<br>
+In this example, we will see how to access a single port pin to blink the LED.
-Writing Logic 1 will set the PORT pin and writing 0 will Clear the particular PORT bit.
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-<script src="https://gist.github.com/SaheblalBagwan/fb344d26c0022cb00b8946efbd8223d4.js"></script>
+<script src="https://gist.github.com/SaheblalBagwan/eb446d21ebdc716914458c6c7fc41a60.js"></script>
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 <br><br>
-===Using Explore Embedded Libraries :===
-In the above tutorial we just discussed how to configure the PORTS for GPIO for blinking the Leds.<br>
-Once you know the GPIO configurations, you can directly use the ExploreEmbedded libraries to play around with LEDs.<br>
-For that you need to include the gpio.c/gpio.h and the associated files(delay/stdutils).<br>
-The below sample code shows how to use the GPIO functions.<br>
-Refer this link for more info on GPIO libraries.
+=Demo=
+[[File:08051 LedBlinking.gif]]
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-<br><br>
 = Downloads=
-Download the complete project folder from the below link:
+Download the complete project folder from [https://github.com/ExploreEmbedded/8051_DevelopmentBoard this link].
-https://codeload.github.com/ExploreEmbedded/Explore-Cortex-M3-LPC1768-Stick-DVB-14001/zip/master<br><br>
-{{#widget:Facebook_Like_Box|profile=https://www.facebook.com/ExploreEmbedded}}
-Have a opinion, suggestion , question or feedback about the article let it out here!
+Have an opinion, suggestion , question or feedback about the article let it out here!
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