Migrating from AVR to STM32 (ARM)
If you are a developer who is experienced in Atmel AVR similar 8 bit microcontrollers now triying to upgrade your skills and move to ARM microcontrollers, this guide will help you know what are the difference you will face on this new platform. So now let us start. Crystal Oscillators and PLLs In good old days, when you wanted to run your AVR microcontroller at 8 MHz or 16 MHz, you simply put a crystal oscillator of that frequency.You can look at a board and if the board has 16MHz crystal you became sure that this board is running at 16MHz. Then you look at a 32bit ARM based board and see it has a crystal of 8MHz, you cry deep in heart and wonder why this poor microcontroller is running at the speed of a snail 🙁 Wait! this is not true! This beast is not running at 8MHz! Here comes the first new concept of this new domain, the PLL. The PLL stands for phased lock loop. Wait, wait, wait! Don’t get scared of this term! From your point of view, that is a software developers point of view this is a very simple thing which multiplies the input frequency and makes it large. So in all ARM based hardware you will find small value crystals like 8MHz […]