SO the SPI clock provide input to a 555 timer, and the timer output is governed by this? I guess this on provides a way of knowing that there's clock on the SPI bus, whereas ideally I wanted to see Tx/Rx. But it's an interesting soluton (and a very nice ASCII schematic!) :-) -marc On 24/7/03 13:13, "Spehro Pefhany" wrote: > At 08:46 PM 7/23/2003 -0400, you wrote: >> I'd like to be able to add some activity LEDs to some SPI bus stuff I've got >> going on a breadboard. I'm sure someone here has a good idea how to do this, >> or a schematic, or horror stories...hence asking before I start :-) >> >> Any clues? > > You could try something like this: > > > VCC LMC555 > +-----------+--------+ > | | |680K > .-. | .-. > | |10K | | | > | | .---'---. | | LED 470R > '-' | 4 & 8 | '-' // ___ > SCK || | | 3|--- | --|>|---|___|-+ > o-||-----+-------|2 | | === > || | 6 & 7|----+ GND > 1000pF |1 5 | | > '-------' --- > | --- 0.1uF > | | > === === > GND GND > > > Best regards, > > Spehro Pefhany --"it's the network..." "The Journey is the reward" > speff@interlog.com Info for manufacturers: http://www.trexon.com > Embedded software/hardware/analog Info for designers: http://www.speff.com > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > -------------------------------------------------- Marc Nicholas Geekythings Inc. C/416.543.4896 UNIX, Database, Security and Networking Consulting -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body