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LPC210x performance-MAMTIM; INT latency questions

Started by roger_lynx March 24, 2004
Hello,

I have started exploring LPC210x. Would anyone comment please, based
on their experience, on the following (that striked me)?

Quote, from the latest data sheet(2003-10-02)- MAMTIM:

" Flash access time is suggested to be 2 CCLKs, while in systems with
system clock faster than 40 MHz, 3 CCLKs are proposed."

1. How *realistic* is to expect LPC210x to run 60MHz with 3 fetch cycles?
2. Is the performance better than with 20MHz and 1 fetch cycle?
Mathematically it appears identical (60/3 /1).

3. What is really the *worst* case for INT latency?
3.1 Best case?

...[700ns given by ARM DDI0234A_7TDMIS_R4.pdf, pg 2-26) @ 40 MHz].
What it would be on LPC210x MCU, at 20MHz/60MHz as mentioned above?

Thank you.

Best regards.
--lynx



An Engineer's Guide to the LPC2100 Series

> 1. How *realistic* is to expect LPC210x to run 60MHz with 3 fetch cycles?
> 2. Is the performance better than with 20MHz and 1 fetch cycle?
> Mathematically it appears identical (60/3 /1).

What MAM unit does is, it gets 128bits from flash at once, so that is
good for 4cycles (4*328). So basicly CPU runs at 60MHz and fetches
128bits at once from flash at 20MHz(considering 3 fetch cycles). This
is ok for sequental code, but sux if there is a lot of irq handling.

/Pero