FAT component timing

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howard123
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FAT component timing

Post by howard123 »

Hello all

I have noticed on my hardware that changing the SD card HighSpeed Pre-scale value has little effect on the time it takes the thing to execute. Measurements that I have obtained are Fosc/4 : 305mS, Fosc/16 : 304mS, Fosc/64 : 306mS. My Oscillator is running at 32MHz and the string I am sending is about 70 characters. In all three observations the string is correctly recorded.

I have the Initial Pre-scale value at Fosc/64 and, at that initialisation time, have the oscillator running at 8MHz. I have not measured this timing.

Any ideas why the period is not changing for different clock speeds?

Regards
Howard
FC 7.2.1.4 PIC18F46K22

howard123
Posts: 75
Joined: Thu May 24, 2012 1:15 pm
Location: Cape Town
Has thanked: 30 times
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Re: FAT component timing

Post by howard123 »

Hi
I have changed the SD card to a 80Mb/s type and all is now ok. Changing the frequency now changes the write speed, which gets down to an acceptable 15mS period.
Howard

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