what is meant by 5 million instructions per second in PIC??

[rangerskm]

how we calculate the speed of instruction in pic??
how it relate to oscillator especially for 12 mhz??

 

[andre_luis]

Instructions per second : 5.000.000
Clock divider : 4x

Oscilator : ( 20.000.000 ) 4 x 5.000.000


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[paulfjujo]

hello,

how we calculate the speed of instruction in pic??
how it relate to oscillator especially for 12 mhz??

Instruction in ASM langage ... not in C or other..

FOSC = FQuartz /4
12/4=> 3Mhz Cyle= 0,33µS
an elementary instruction as a NOP ( do nothing) is executed in 0,33µS
so you can calculate how many instructions in one second : 1000000/0.33=> more the 3 000 000 per second
but somme instruction can take 2 or 3 cycles .. so reality can be less than 3 Millions per second.

Some PIC have a PLL circuit to multiply by 4 , the Quartz Fosc
FOSC becomes 12x4=48Mhz divide by 4 to get elementary Cycle time for a NOP instruction
so if used in this example => gives maxi = 12 Millions instruction per second

 

[andre_luis]

...but some instruction can take 2 or 3 cycles...

I don´t know other families than PIC16F, but this one takes exactly 4 cycles oscilator per instruction...


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[jayanth.devarayanadurga]

It means 5 million nop instructions get executed in 1 sec.

 

[paulfjujo]

I don´t know other families than PIC16F, but this one takes exactly 4 cycles oscilator per instruction...


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Machine cycle = FOSC/4 .. OK

to execut a
goto xxxx or a conditioanl branch or return or Call
it takes 2 "machine cycle"
see PIC16XXX instruction set in datasheet for nb of cycle for each instruction.