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Re: MMC filesystem speed

2005-11-27 by rtstofer

A different measurement:  Using the LPC2106 at 4 * 14.7456 MHz, 
portions of the WinAVR FAT12/16/32 library and a Kingston 64MB CF, I 
can read 350 KB/s.

The timing was measured while perfoming 10 loops of:
open_file
read_entire_file (6,198,940 bytes)
close file

It took 2m 57s

I haven't looking at the byte transfer timing to see if it can be 
kicked up but I would think it wouldn't go much faster.  After all, 
I haven't implemented any 'wait' state:

void ataReadDataBuffer(unsigned char *Buffer, unsigned short 
numBytes)
{
unsigned short i;

// set up device
IOCLR  = ADDR_MASK;
IODIR &= DB_INPUT;
CS(CS_CF);// select device
	
// read data from drive
for (i=0; i < numBytes; i++)
{
 IOCLR = OEn_MASK;// set OEn low
 *Buffer++ = IOPIN >> DATA_SHIFT;
 IOSET = OEn_MASK;// set OEn high
}
CS(CS_NONE);// deselect device
}

I also haven't reviewed the Kingston spec or tried any of 
the 'faster' CF devices.  About the only thing that 'could' improve 
would be seek time.

For my MP3 application I need to transfer about 1 MB/minute and I am 
about 20 times faster than required.

Richard

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