Timing issue with NEW atmega 168 and 328

Other Hardware 3rd Party Boards
1

Hi

I was using an old atmega 168 and 328 and I programmed it so many time with my code and everything was working well. Now recently I bought brand new atmegas with the same part number as the previuos 1s and now theres a timing issue on the microcontrollers. I dont understand why if I program the new1 with the old 1 then the new mcu doesnt operate the same as the old 1. I had to use change the timing using the infomation given on the address below

http://arduino.cc/playground/Main/TimerPWMCheatsheet

It changes the timing but i dont get the proper timing i get on the old arduino. Please help

2

Did you burn the Arduino bootloader on the new chips?

From the factory the chip uses the internal 8 MHz Resistor-Capacitor oscillator with a pre-scale of 8 so it runs at 1 MHz. Pert of the bootloader burning process is to set the chip to use the external 16 MHz crystal/resonator with a pre-scale of 1 so the chip runs at 16 MHz.