-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Timothy Miller wrote: > On 6/10/06, Hamish <[EMAIL PROTECTED]> wrote: >> >> What exactly doesn't it like about the code? Is it somply >> complaining because there's two (Almost) identical always blocks >> >> always @(posedge clock) SCK_reg <= #1 1; always @(negedge clock) >> SCK_reg <= #1 CE_; >> >> Which both assign to SCK_reg? In which case it doesn't seem to >> understand that (presumably) SCK_reg should be assigned 1 on the >> rising edge of the clock, and CE_ on the falling edge... >> >> Do I read it correctly? And what should be the way to specify an >> action on the rising or falling edge of the clock in verilog? >> >> [Sorry. Just wondering really if I'm reading this correctly]. > > There isn't one in Verilog. For synthesis, you cannot assign to > the same net or register from two different places, and there's no > construct for assigning on two edges. (Although, you can assign to > A on pos, B on neg, and then mux them together, but that's not what > we want.) I had given this as a simulation-only example, but > Petter put it in his code directly. > > The solution is to use a DDR flipflop I/O buffer, and the correct > one for Lattice is this: > > ODDRXC ddr_ff (.CLK(clock), .DA(for_rising), .DB(for_falling), > .RST(reset), .Q(to_pin)); >
I understand some of that statement... But not fully... You couldn't tell me exactly how that works could you? (It's the verilog syntax that I don't get, not the concept of using the FF). Especially the slightly different ODDRXB sck_buf (.DA(1'b0), .DB(CE_) , .LSR (1'b0), .CLK (clock), .Q (SCK)); that appears in the code... What's the diff between ODDRXB and ODDRXC? And the .LSR is what? Sorry. I don't have a verilog reference yet... Amazon (.co.uk) don't seem to have any that I can find that are particularly relevant... Except where they're several hundred pounds... regards Hamish. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFEjT0j/3QXwQQkZYwRAqeWAJ44LXVsEU9uIlvC+vMkqNwSfVmCbACfZmbp uafbyK2S0AU0cFG7AzQl/qo= =NV68 -----END PGP SIGNATURE----- _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
