I have designed the hardware using ATMEGA328PU(32 pin flat package) at 3.3V , 8MHz external crystal oscillator,
I am able to successfully burn the boot loader and flashed blink code compiled for ARduino Mini pro @ 3.3V / 8MHz.
The problem I faced is that after flashing the blink code ,I can't upload another patch of the code.
For which I tried few times burning the boot loader and uploading the code. Which went well.
Is there any possible way i could stop this practice ?
I couldn't find a relevant solution for this.
Usually that means missing or incorrect auto-reset circuitry. The ATmega328P needs to be reset to activate the bootloader. If you connect the DTR line from your USB to TTL serial adapter chip to the ATmega328P reset pin via a 0.1 uF capacitor it will be automatically reset at just the right time. If you don't have that connection then you need to manually reset the chip just as the upload starts (after compilation finishes). It's not necessary to do this the first time you upload after burning the bootloader because at that point the bootloader is constantly activated.
The other common cause of this is people doing an "Upload Using Programmer" without realizing that erases the bootloader. You always need to do a Burn Bootloader after Upload Using Programmer before you can go back to uploading over serial again.