We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.
Hello,
I've been working with a board MCBSTR9 and I thought I had correctly configured the PLL so that I was working at the maximum frequency.
However, revising the configuration in the startup file provided by Keil, I've seen that the following values were set in the PLL configuration:
P = 3; N = 192; M = 25
, which, according to all the manuals I've seen, produces an fPLL frequency of 48MHz (the oscillator's frequency is 25MHz).
So, I changed the value of P to 2, to theorically get a frequency of 96MHz. However, the board don't even start running.
I changed the parameters to several values which should produce a 96MHz output in the PLL, but nothing worked. Restoring a frequency of 48MHz works fine.
I can't see where's my mistake. What am I doing wrong?
As usual, I don't have access to any of my code while looking at this forum.
At the moment, all I can say is that I've been using the Keil STR9 board and been running it at the full 96MHz. From memory it was a revision 'g' and our own in-house developed prototype has a revision 'h' - The stepping level may be wrong here, but I do remember that our proto has the latest and the Keil board has the previous one.
All timers, clocks etc work at the expected clock speeds. Currently, I'm going for 'flat out' on as much as possible.
When I was first exploring the CPU, I used the debugger, single stepped into the code and examined the clock registers - Modifying them to see what effect it had on all the clock outputs. Coming from an 8051 background and being new to the ARM I found the number of registers and combinations daunting.
If you're still asking on Monday, I should be able to access my code and may be able to help you.
Good luck.