Electronics > Beginners
SPI trace length
<< < (3/3)
David Hess:

--- Quote from: rstofer on June 19, 2018, 02:57:17 pm ---How fast is fast?  I'd hate to think we're talking about 1 MHz and below at 1 foot of trace.
--- End quote ---

1 foot is about 1.5 nanoseconds so no problem with most unterminated CMOS.  This is the length where fast CMOS starts to have problems which you can see on a fast oscilloscope.


--- Quote ---I'm running a 6" cable (unterminated) between an FPGA and an LPC1768 at around 12.5 MHz and there has never been a problem.  There are 200 Ohm series resistors on the FPGA board to protect the pins and eliminate reflections.  3.3V logic...
--- End quote ---

6 inches is 0.75 nanoseconds so even less of a problem especially with 200 ohm series resistors limiting rise and fall time.
Navigation
Message Index
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod