HI,
I am new to AT89c51 MUC.I have used keil for coding to the controller.BUt how to burn this code to the controller.I don't want to buy the programmer....How to design my own programming circuit..

 

You can buy programmers for like 3$ on eBay.

 

can u explain me the circuit ...why we should use only 22pf capcitor at crystal....why every controller needs an external crystal......use of PSEN....use of reset circuit

 

can u explain me the circuit ...why we should use only 22pf capcitor at crystal....why every controller needs an external crystal......use of PSEN....use of reset circuit

Second question first. NOT EVERY controller needs external crystal. In the past 5 years manufacturers started making controllers that don't need external crystals. However, older and today cheaper microcontrollers still use external crystals. 89C51RD2 is not exactly old, but it has been on the market for the last 10? 15 years?, when it was developed the normal procedure was to use external crystals.

First question now. The crystal that you buy will have specification in its datasheet of what value capacitors to use. Whoever designed that circuit found the crystal they liked, read the crystal datasheet, saw that the crystal needs 22 pF capacitors and put those capacitors into the schematic.

This is actually interesting choice of microcontroller. 89C51RD2 has bootloader so you don't need programmer device, you connect the 89C51RD2 directly to computer and send the hex file to the 89C51RD2. The problem is that you connect 89C51RD2 to the computer serial port. It is problem because 89C51RD2 uses 5 volts, computer serial port uses -3 to -25 volts and +3 to +25 volts, so you use MAX232 chip to translate computer serial port voltages to the 89C51RD2 voltages. The great thing about RD2 chips is that you don't need programmer, they come from the factory with the bootloader, just buid/buy MAX232 circuit above to connect it to pc and use FlashMagic/EasyIAP/etc program to send the hex file to the 89C51RD2.

Now the bad news. Philips P89C51RD2 was discontinued in 2012. The replacements are still available, just look for RD2 in the replacement model name and check that it comes loaded with bootloader.

 

what is the need of external crystal

 

what is the need of external crystal

Clock/control signal.

 

PSEN (Program Store ENable - bar) was a signal in the original 8051 architecture that was used to read instructions from an external memory device. When held high during RESET it enters the bootloader.

 

You can buy programmers for like 3$ on eBay.

If i directly solder this circuit on a zero board ,will this wok perfectly.......I want to burn the code serially.......

 

HI,
I am new to AT89c51 MUC.I have used keil for coding to the controller.BUt how to burn this code to the controller.I don't want to buy the programmer....How to design my own programming circuit..

here is your solution

http://www.firmcodes.com/microcontrollers/8051-3/

 

here is your solution

http://www.firmcodes.com/microcontrollers/8051-3/

Hi Vishal,
Thanks for your reply.But i did not get any info related to my question here.I know about the features of controller but i need hard ware to burn code to the micro controller.