Some AVR uc related stuff

Hi,

I apologies for not writing blog for few days because of some tight schedule i was having at my college.But Krishna Janam Ashtami gave me some time to make another post.

1. The Input Capture unit is easy to use in normal mode(WGM13=0).However,observe that the maximum interval between the external events must not exceed the resolution of the counter.

Things one can do to increase the resolution :

If the interval between the events is too long,the timer overflow(inc a software counter/any register) or prescalar must be used to extend the resolution of the capture unit.

2. Constants can also be stored in the program memory as they need not to be reprogrammed or changed too often.

How to do that?

#include "avr/pgmspace.h"

const char table[480] PROGMEM ={} also calculate the amount of memory it will eat/consume.

There should be enough memory left for APM(Application Program Memory) & BPM(Bootloader program memory) in the whole progrqam memory map

3. Two stage pipeline in AVR -

Any instruction you give to the micro-controller undergoes following routine of FDE :

Fetch -----Register ---------Decode----Register --------Execute

It appears as if each instruction is taking lesser clock cycle to execute


4. Why two sets of registers in AVR ATmega8 (in 32 General purpose register ):

Explaination :

For example if i have a instruction like :

ldi r6,$3f

$3f is 8 bits,ldi consumes let say 4 bits.then i am left with only four bits which can be used to represent 16 registers.therefore,16-31 are separate and 16 instructions including ldi are possible only with these(16-31)