Any such counter available?

David Chance said:

n my project, I need a counter with the following characteristic but didn't find it on TC4M1294, but I would like to confirm that is indeed the case before I construct one with CPLD.

 Why internal Capture counter register was not considered to do this task?

Hello David,

An external clock source to run the counter is only possible in RTC mode but the prescalar would be fixed in that case. Other than this, the remaining requirements can be met by the General Purpose Timers.

Regards

Amit

Hi Amit,

I need to revisit this topic.

According to you, if external clock source is required, I have to use RTC mode, yet according to data sheet, "To use the RTC mode, the timer must have a 32.768-KHz input signal on an even CCP input."

So I can't use 16Mhz clock source input?

Thanks for your reply.

Sorry, it took so long before I can revisit this topic (now my project must decides how to implement it).

"internal Capture counter register"? It seems Amit's reply implies RTC is the only choice, could you point me to further reading or insight?

Thanks!

Hello David

Yes, the RTC Mode requires an external 32768Hz clock on the CCP Pin. But in this case the pre-dividers are fixed.

Regards

Amit

Sorry, but I am still a little confused.

Do you mean that since I have to use an external 16Mhz clock as signal source, to count up a reset-able 32-bit counter, 1294 is NOT a good candidate?

If that's the case, how about 123? it seems to be more powerful

Hello David,

What I meant is that the external clock source in RTC Mode cannot be more than 32768Hz. Using 16MHz external clock directly to the timer in RTC Mode may not work

Regards

Amit

I got that implication, that's why I question if I have a solution on 1294 for my request:

~16.394Mhz clock source

32-bit up-counter (auto wraps around)

The counter is reset-able at any time

I can read the counter while it is running

Hello David,

Sourcing the clock from external to run the counter directly is not possible, so not being able to meet the prime requirement would be a concern for your project.

Regards

Amit

Would the the closest solution be the general purpose timer (16 bit + 8 bit prescaler)?

Hi,

Do you need to use the Ethernet module? If yes, maybe there is no solution (counting edges?...) 

If not, a good candidate could be also to use the external clock as system clock (if always present) and then a 32 bit timer will do the job since the timers gets the system clock as input (Set it to count up with the limit 0xFFFFFFFF).

Petrei

I am afraid so, I do need ethernet....

On page 956 (Figure 13-1) of tm4c1294ncpdt data sheet, it mentioned 32/64 bit up/down counter modes, but not other place, is it a typo?

Hello David,

Yes, it is a Typo. Thanks for bringing it to our notice.

Regards

Amit