alliance-support '02
Re: Register Problem-Pls help


Francois DONNET (francois.donnet@asim.lip6.fr)
Fri, 01 Feb 2002 11:17:34 +0100

GIIE wrote: > Hello again sir, > > I am designing a register file of 32 registers of 32 > bits each. All have a common input 'data_in'. First, I wrote the > behavioral description of a 32 bit register, simulated it etc - there > were no errors. Next, I cascaded it in a structural description for > the 32 registers. I connected all the outputs of the individual > registers together because I wanted a bus since the register block > would have read and write pin. Checking for syntax errors : no > problem. I wrote the pattern file, and then I recieve the following > errors upon simulation: > > Error 114: multiple driver on unguarded signal `reg_dataout 0` > Error 114: multiple driver on unguarded signal `reg_dataout 1` > Error 114: multiple driver on unguarded signal `reg_dataout 2` > Error 114: multiple driver on unguarded signal `reg_dataout 3` > Error 114: multiple driver on unguarded signal `reg_dataout 4` > Error 114: multiple dr! iver on unguarded signal `reg_dataout 5` > ****( this continues for until reg_dataout 31) > > I sense the errors are with the declaration of "reg_dataout" in the > structural description. I declared it as > "Reg_Dataout : out bit_vector(31 downto 0) ". Changing this to > "Reg_Dataout : out mux_vector(31 downto 0) Bus" results in even more > errors. Looking at the documentation(ASIM website) for the allowed > structural subset, it was not stated whether the "mux_vector..." can > be used in a structural description. > Q1: Is the statement "Reg_Dataout : out mux_vector(31 downto 0) Bus" > acceptable in a structural description? > Yes you can(must) use it, it will solve the multiple drivers error! Maybe now the other errors are simulation errors, aren't they??? Or it is the kind of register output...... What kind of register are you using? > > Q2. With the explanation of my given circuit, how can I declare a bus > for register file output "Reg_dataout" so that I could use the "read" > pins in my design to select which of the 32 register content I want on > placed the bus. > If simple registers are used, you should connect each of their output to a tristate. Each tristate output would be connected to the external bus connector The tristate command to external connector named read. > > Thanks, > Giie > > > ----------------------------------------------------------------------- > Do You Yahoo!? > Yahoo! Auctions Great stuff seeking new owners! Bid now!

 



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