| ??? 01/29/09 16:12 Read: times |
#161825 - 321 Interrupts Responding to: ???'s previous message |
You mentioned 321 interrupts......did you actually mean 321 interrupts per second?
Some sanity check things to investigate: 1) Does the Timer 2 in the published example you are referenced clock at the same rate as your setup?? 2) Does Timer 2's clock really happen at the XTAL frequency?? If the reference example clocked at the same 12.58 MHz as your setup AND the Timer 2 was clocking at 1/12 th of the XTAL rate the the 321 computation may be incorrect. It just so happens that 321 / 12 == 26.75 which is a whole lot closer to ~20Hz!! Often times in working with the timer it is useful to read data sheet to understanding what you think to be true, then make up some test code and try out on target platform. Toggle some port pin and measure on an oscilloscope to see if your understanding was correct. Even experienced folks will find they are off by some factor as they missed some detail such as the timer clock being prescaled by a divide by two or some other strange factlett. Michael Karas |
| Topic | Author | Date |
| ADUC845 Timer2 Control Basics | 01/01/70 00:00 | |
| Well well... | 01/01/70 00:00 | |
| I'm guessing you already know.. | 01/01/70 00:00 | |
| Doesn't clarify why that value | 01/01/70 00:00 | |
| the absolute duration of one timer tick... | 01/01/70 00:00 | |
| not important, but what is | 01/01/70 00:00 | |
| The timer tutorial was not helpful | 01/01/70 00:00 | |
| It's the math that doesn't seem to work | 01/01/70 00:00 | |
| 321 Interrupts | 01/01/70 00:00 | |
| Experimental path probably best | 01/01/70 00:00 | |
| BTW - XLS Modeling | 01/01/70 00:00 | |
Timer counters connected to PLL | 01/01/70 00:00 |