Thank You Andrew And James, We are referring to the same clock, clk(i-1) and clk(i+1), I used clck(i-1) notation to signify the one that comes right after clk(i), my mistake, I am thinking of delayed clock cycle relative to clk(i) as being clk(i-1). I will use your notation in my next question: Tval (Max) and Tval (min) Is Tval(max) measured relative to clk(i) and Tval(min) measured relative to clk(i+1)? Thanks again, Brahim "Ingraham, Andrew" wrote: > > Tval is measured as the delay time between clk(i) and when the data is > > valid, clk(i) precedes the data, > > Tval is measured at the driver output. > > > > 1. Once the signals, clk and data arrive at the receiver, which clock > > samples the data? > > Is it clk(i) or clk(i-1)? > > Neither. It is clk(i+1), the one that comes next after clk(i). > > All PCI transfers go from one clock cycle to the next. On the rising edge of > clock, outputs start to drive data after a delay of Tval. Shortly (Tsu) > before the next rising edge of clock, the data that was sent is ready to be > received by an input. > > All this is happening all the time. Data outputs are being driven on all > clock cycles, and received on all clock cycles, one clock cycle after being > sent. > > > 2. The clock signal is from a board to the PCI expansion card, how's > > the data sampled by a board > > when the data is originating from the card? > > The clocks are timed to arrive at all devices on the bus at about the same > time, even those on PCI expansion cards. > > The data signals get from the expansion card to the motherboard through the > PCI connector. The PCI connector makes an electrical connection for all > signals on the bus. It is the same as if the device on the card was on the > motherboard, except that the "wires" to/from that device are longer (and > noisier). > > Andy ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu