SPI bus and wire length?

Archiver

How long can the wire connections be on a SPI bus? The reason I am
asking this is I want to interface to a MAX6674 from Maxim to a BS2
40P that is going to be 6 feet away or more with shielded, twisted
pair cable. Will this work or am I pushing this technology? Should I
use series termination on the SPI bus to slow the edges down to
minimize overshoot/undershoot? The MAX 6674 is going to be located as
close to the thermocouple as possible to improve it's accuracy.

Jason

Archiver

Jason,

Since you are doing SPI with 6674 (I need to do the same in a near
future) can you recommend a good explanation of SPI? In my case it
should be simple two slaves (6674, and a DAC) single master project.
Neither Scott's book, no Al's give any details. I looked at MAXIM
site and have not found much either. Sorry to bother you.

Thanks a million.

Alex.


--- In basicstamps@y..., "jbirnsch" <jbirnsch@v...> wrote:
> How long can the wire connections be on a SPI bus? The reason I am
> asking this is I want to interface to a MAX6674 from Maxim to a BS2
> 40P that is going to be 6 feet away or more with shielded, twisted
> pair cable. Will this work or am I pushing this technology? Should
I
> use series termination on the SPI bus to slow the edges down to
> minimize overshoot/undershoot? The MAX 6674 is going to be located
as
> close to the thermocouple as possible to improve it's accuracy.
>
> Jason

Archiver

SPI aka Microwire aka 3/4 wire bus. Consists of a serial data in line , serial
data out
line(may only have 1 of these), a clock line and a chip select. Not sure of the
maximum clock speed. On the STAMP you use the Shiftin/out
command(data,clock) along with chip select on an i/o pin.
Motorola site should have specs.

>
> Since you are doing SPI with 6674 (I need to do the same in a near
> future) can you recommend a good explanation of SPI?