micron sdram module

Hi,

still sticked in the sdram controller project. I use a micron 256mb
sdram

following is its datasheet  and simulation module's web address :

http://www.micron.com/products/DRAM/SDRAM/part.aspx?part=MT48LC16M16A2TG

I now want to know whether a read or write successful or not. Can
someone tell me which array of variable in micron's simulation module
I should put in the "watch" ? The micron module is quite complicated.
I have problem now to get the timing right. Of course I know if I
cannot read the thing I write, it is wrong, problem is that maybe the
read has a bad timing too. So I need to see the internal content.

I use vhdl module.

Thanks


Steven

Steven wrote:
> Hi,
> 
> I now want to know whether a read or write successful or not. Can
> someone tell me which array of variable in micron's simulation module
> I should put in the "watch" ? The micron module is quite complicated.
> I have problem now to get the timing right. Of course I know if I
> cannot read the thing I write, it is wrong, problem is that maybe the
> read has a bad timing too. So I need to see the internal content.
> 
> I use vhdl module.

That should be easy to determine from the source code. The data is 
stored in the variables Bank0-3. But if you can cosimulate with Verilog, 
I would suggest using the Verilog model. It is more up to date, though 
judging by the change log the changes are relatively minor. But a big 
advantage is that it prints out reads and writes, including the address 
and contents. Though in some situations that might be considered a 
disadvantage.

-- 
My real email is akamail.com@dclark (or something like that).

Duane Clark <junkmail@junkmail.com> wrote in message news:<cd1coq08fu@news2.newsguy.com>...
> Steven wrote:
> > Hi,
> > 
> > I now want to know whether a read or write successful or not. Can
> > someone tell me which array of variable in micron's simulation module
> > I should put in the "watch" ? The micron module is quite complicated.
> > I have problem now to get the timing right. Of course I know if I
> > cannot read the thing I write, it is wrong, problem is that maybe the
> > read has a bad timing too. So I need to see the internal content.
> > 
> > I use vhdl module.
> 
> That should be easy to determine from the source code. The data is 
> stored in the variables Bank0-3. But if you can cosimulate with Verilog, 
> I would suggest using the Verilog model. It is more up to date, though 
> judging by the change log the changes are relatively minor. But a big 
> advantage is that it prints out reads and writes, including the address 
> and contents. Though in some situations that might be considered a 
> disadvantage.

Steven,

    I have a similar problem in that I have downloaded a SDRAM VHDL
module from the Micron website and have developed a master peripheral
to the Avalon Bus using SOPC Builder in Quartus.  In this, I merely
connect to the SDRAM controller which is physically connected to a
128Mbit Micron SDRAM.   When attempting to simulate this SOPC design
interfaced directly to the SDRAM module from Micron, I don't manage to
see any of the data that I have put in the WRITE phase, as when I do a
READ I get crap out.   The verilog doesn't work well as I have not
managed to be able to interface Verilog and VHDL properly within the
same design.  Definitley my lack of experience in this area to doing
it correctly.  So perhaps this is a similar issue, but I am unclear
what the MICRON module is supposed to do as I don't see anything
coming out?   Is the module supposed to retain information and return
it on the bus when you request it (i.e a READ)?

REgards,
Pino

if you are writing to SDRAM module you can check value written at lines:
    ...
-- Write back to memory
                    IF Bank = "00" THEN
                        Bank0 (Row_index) (Col_index) := Dq_temp;
                    ELSIF Bank = "01" THEN
                        Bank1 (Row_index) (Col_index) := Dq_temp;
                    ELSIF Bank = "10" THEN
                        Bank2 (Row_index) (Col_index) := Dq_temp;
                    ELSIF Bank = "11" THEN
                        Bank3 (Row_index) (Col_index) := Dq_temp;
                    END IF;
    ....
--

 and if you read you may check:
...
ELSIF Data_out_enable = '1' THEN
           IF Dqm_reg0 /= "1111" THEN
                    -- Initialize memory
                    Init_mem (Bank, Row_index);
                    -- Load memory into buffer
                    IF Bank = "00" THEN
                        Dq_temp := Bank0 (Row_index) (Col_index);
                    ELSIF Bank = "01" THEN
                        Dq_temp := Bank1 (Row_index) (Col_index);
                    ELSIF Bank = "10" THEN
                        Dq_temp := Bank2 (Row_index) (Col_index);
                    ELSIF Bank = "11" THEN
                        Dq_temp := Bank3 (Row_index) (Col_index);
                    END IF;
...

in micron VHDL SDRAM simulation model (example for quad bank 64Mb Micron
model)
I've designed simple sdram controller with testbench instantiating Micron
SDRAM 32Mx2 model,
you can check it at http://www.geocities.com/mikael262/sdram.html

Mike

> > That should be easy to determine from the source code. The data is 
> > stored in the variables Bank0-3. But if you can cosimulate with Verilog, 
> > I would suggest using the Verilog model. It is more up to date, though 
> > judging by the change log the changes are relatively minor. But a big 
> > advantage is that it prints out reads and writes, including the address 
> > and contents. Though in some situations that might be considered a 
> > disadvantage.

Thanks, Duane. It is quite obviously that Bank0-3 hold the memory
contents. :)
It is too large to put in the watch list. 64MB or more of each bank.
Anyway thanks. The other tip from you is great, verilog module gives
more info. Maybe micron also do not like old europe so they do not
include such useful output in vhdl module. :)


> 
>Definitley my lack of experience in this area to doing
> it correctly.  So perhaps this is a similar issue, but I am unclear
> what the MICRON module is supposed to do as I don't see anything
> coming out?   Is the module supposed to retain information and return
> it on the bus when you request it (i.e a READ)?
> 
> REgards,
> Pino

Yes, Pino. The module works like physical module, only for simulation.
It executes Read/Write command from your sdram controller, and holds
the contents.

Pino wrote:
> 
>  ...   The verilog doesn't work well as I have not
> managed to be able to interface Verilog and VHDL properly within the
> same design.  

There is nothing special required for Modelsim, though I can't say about 
other simulators. You just instantiate a Verilog module as if it were a 
VHDL entity:
    -- MICRON DDR SDRAM Simulation Model
    MEM1 : entity micron.ddr
       port map (
          dq          => DDR_DQ(0 to 15),
          dqs         => DDR_DQS(0 to 1),
          addr        => DDR_Addr,
          ba          => DDR_BankAddr,
          clk         => DDR_Clk,
          clk_n       => DDR_Clkn,
          cke         => DDR_CKE,
          cs_n        => DDR_CSn,
          ras_n       => DDR_RASn,
          cas_n       => DDR_CASn,
          we_n        => DDR_WEn,
          dm          => DDR_DM(0 to 1)
          );


-- 
My real email is akamail.com@dclark (or something like that).