http://www.8051projects.net/ Learn to make simple microcontroller projects, pic, 8051, avr and arm projects. download 8051 projects, tutorials, libraries, sample codes. join the microcontroller discussion forum and ask doubts regarding electronics. the best source for 8051 over internet. en-gb 2008-12-01T23:46:06-08:00 contact@nospam.com hourly 1 2000-01-01T12:00+00:00 http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 Today I got my first microcontroller programmer for 8051 from www.sunrom.com (1001-3456 v2)I downloaded the example hex file provided by sunrom to the AT89C51. It was a very simple example to blink the LED connected to any pin of port 2.I designed the following circuit in Proteus ISIS and it ran successfully without any error with the attached HEX code. But when I designed the same circuit on the Breadboard then the same is not blinking the LED, instead it just turn on the LED. I cross checked all the connections and found that connections are correct. I downloaded the HEX file on another AT89C51 and tried.. again the same thing.What is wrong, please help me. Can anyone try this at their end and PLEASE let me know where I am wrong! http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 say2paul Please find attached the zip file containing the C and HEX code. ledtest.zip http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 ۞ TPS ۞ you are not using pin no 9(RST) and 31 EA/VPP Connect it properly you will get the result best of luck Please Use This Circuit http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 sashijoseph Have you provided a proper power-on reset ckt?Is your xtal close to the micro's pins?The code is ok.Try increasing the delay 2 or 3 folds. http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 ۞ TPS ۞ http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 say2paul Thanks TPS and sashijoseph, I dont have the required capacitor for reset circuit right now. I will get it in the morning and will test the circuit and let you know.And TPS that a lot for the Breadboarg diagram http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 say2paul Thanks its working fine now. The power on reset circuit really worked!P.S. I noticed that the blinking of Led starts after 1-2 seconds I supply the power to the circuit, might be because of 10uF 63V capacitor. http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 Ajay sure you can.. as you are working with 5V only http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 say2paul I will try it with 10uF 25V capacitor instead! http://www.8051projects.net/forum-t10422.html 2008-12-01T23:46:06-08:00 say2paul yes!!