[51] C8051F380 Timer0 Time period Calculation

[KVSN91]

Hi, I am learning 8051 Microcontroller(Choosing C8051F380 siliconlabs).Timers are used to creating frequency and time period.I didn't understand How to calculate Time period.
i understood my self to produce time period using TIMER0 , first we should know high and ,low frequencies we can produce using prescaler.
For ex my sysclok 48Mhz, i take prescaler SYSCLK/48,
ie.. 48Mhz/48=1 Mhz
for T= 1/ 1 Mhz =1us. ie.. 1sec like that

I take now prescaler Syscl/12
ie.. 48Mhz/12=4 mhz;
for T= 1/2Mhz=0.25 sec


Now please explain briefly How to calculate Time period and Frequency using Using Timer0 (13bit,16bit,8bit auto reload,two 8bit) . I am using C8051F380 controller

 

[KlausST]

Hi,

You need to tak care about your capital letters and metric prefixes in general.

for T= 1/ 1 Mhz =1us. ie.. 1sec like that

it is not 1sec, but it i 1 microsecond = (1/ 1000000) s

48Mhz/12=4 mhz;

--> 48MHz/12=4 MHz; it is not millihertz, but megahertz

for T= 1/2Mhz=0.25 sec

--> it is not 0.25s but it is 0.25us = 250ns = 250 nanoseconds

The prescaler output is the input to the counter.
(I'm not familiar with 8051, but isn't there an additonal fixed prescaler of 4?)

In either case:
If counter input frequency is 1MHz and the counter counts 100 steps each, then the output is 1MHz / 100 = 10kHz.
A time period of 1/10kHz = 100us = 100 microseconds.

All this you can read in the datasheet and thousands of tutorials.

Klaus

 

[Okada]

Did you google ?

https://embetronix.wordpress.com/2010/09/14/timer-calculation-in-8051/

https://www.8051projects.net/download-d115-8051-time-delaytimer-routine-calculator.html