SD card to pic ( speed question )

J

JasonL220

New Member

• Nov 11, 2006

• #1

i want to connect a PIC18F4450 to and sd card, but i'm wondering what speed the data will come from a card clocked at 48Mhz with a date rate of 25 MB/s.
How many nanoseconds will a high/low pulse last?
Does data on the command line get sent at the same speed?

thanks

 

P

Pommie

Well-Known Member

Most Helpful Member

• Nov 11, 2006

• #2

As nobody has attempted an answer yet, I thought I would give you my best guess.

I guess it would be around 25,000,000 bits per second. I'm also guessing that a high/low pulse will last around 10^9/25,000,000/2 nS or 20nS.

Mike.

 

J

JasonL220

New Member

• Nov 11, 2006

• #3

thanks that was around the value i was thinking just wonder if anyone knew, back to the datasheet have to take a much closer look at the timing diagrams.

thanks Pommie

 

J

JasonL220

New Member

• Nov 11, 2006

• #4

could someone look at page 29 of this **broken link removed** and try an work out the pulse time for input and output?

i got output = 36ns and input = 20ns

could someone check this please?

thanks

 

gramo

New Member

• Nov 14, 2006

• #5

Once again, basic makes life easy for everyone, check out the following link for an addon in Proton+ made by Steven Wright, of course you need the full version of Proton to use it, but hey, a SD card interface with a few commands that generates FAT16 files so any PC can read them - im there

**broken link removed**