SigNoise errors/warnings during simulation

We are trying to simulate a topology.Driver is MPC8349EHere are the Models available for DDR2. ddr2_io_0000  - DDRII, 1.8v, 36 Ohm, Much Higher Z than nominal ddr2_io_0001  - DDRII, 1.8v, 23 Ohm, Very High Z than nominal ddr2_io_0011  - DDRII, 1.8v, 20 Ohm, Higher Z than nominal ddr2_io_0111  - DDRII, 1.8v, 18 Ohm, Nominal Z ddr2_io_1111  - DDRII, 1.8v, 16 Ohm, Lower Z than nominal ddr2_i_150_Ohm_term  - DDRII input with 150 Ohm ODT ddr2_i_75_Ohm_term   - DDRII input with 75 Ohm ODT ddr2_i_no_term       - DDRII input without ODTI am simply analysing one data line.We took  ddr2_io_0000 model as driver and MT47H256M8EB-25EC as receiver.Topology is like thisDriver(ddr2_io_0000) ----> MS1(50 Ohms, 100mils Length)---> SL1(lengthvaried linearly from 1000 mils to 5000 mils) ---> MS2(50 Ohms, 100mils)--->DDR2(DQ_FULL_ODT75/50/150/No ODT_533).When we simulate MPC8349E as driver, i didn't get any Convergence issue,  ican see all the results and waveforms.But if we change DDR2 to driver and MPC8349E to receiver (To simulate DDR2read situation)*I am getting Convergence error and lot of failures.**Signoise Errors/Warnings*ERRORS:Simulation (DESIGN IO4 1) DESIGN IO4 1 Pulse Slow Reflection FailedSimulation (DESIGN IO4 1) DESIGN IO4 1 Pulse Typ Reflection FailedSimulation (DESIGN IO4 1) DESIGN IO4 1 Pulse Fast Reflection FailedWARNINGS:SERIOUS WARNING(SPSIMS-73): Convergence Problem in Simulation of "DESIGNIO4 1" stimulus Pulse.What needs to be done to this?We need one clarification:There are different models for MPC8349EFew are Io models and few are Input only models.During READ simulation,whether we need to use different model like ddr2_i_75_Ohm_term   - DDRIIinput with 75 Ohm ODT*or same model(*ddr2_io_0000)?Screenshot http://postimg.org/image/f6bzr3h61/
malli.1729 6 years 26 days

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Answered bymalli.1729 6 years 24 days
DDR2 controller has specified different models, i need to use a differentmodel of input type with ODT for Read simulation.DDR2 memory also i have used IO model with ODT enabled. We should use IOmodel without ODT.When  I have done that, i am not seeing any convergence problems andresults look OK.Thank you all,On Thu, Nov 6, 2014 at 9:38 AM, Ferhat Yaldiz wrote:> You can reduce timestep for overcoming this convergence error.>> You can use different ODT options for receive operation. You must> investigate> DDRx controller chapter of your MPU manual for this.>> Ferhat Yaldiz>> On Wed, Nov 5, 2014 at 3:14 AM, Mallikarjun K > wrote:>>> We are trying to simulate a topology.>> Driver is MPC8349E>> Here are the Models available for DDR2.>>  ddr2_io_0000  - DDRII, 1.8v, 36 Ohm, Much Higher Z than nominal>>  ddr2_io_0001  - DDRII, 1.8v, 23 Ohm, Very High Z than nominal>>  ddr2_io_0011  - DDRII, 1.8v, 20 Ohm, Higher Z than nominal>>  ddr2_io_0111  - DDRII, 1.8v, 18 Ohm, Nominal Z>>  ddr2_io_1111  - DDRII, 1.8v, 16 Ohm, Lower Z than nominal>>  ddr2_i_150_Ohm_term  - DDRII input with 150 Ohm ODT>>  ddr2_i_75_Ohm_term   - DDRII input with 75 Ohm ODT>>  ddr2_i_no_term       - DDRII input without ODT>>>> I am simply analysing one data line.>> We took  ddr2_io_0000 model as driver and MT47H256M8EB-25EC as receiver.>> Topology is like this>> Driver(ddr2_io_0000) ----> MS1(50 Ohms, 100mils Length)---> SL1(length>> varied linearly from 1000 mils to 5000 mils) ---> MS2(50 Ohms,>> 100mils)--->>> DDR2(DQ_FULL_ODT75/50/150/No ODT_533).>>>> When we simulate MPC8349E as driver, i didn't get any Convergence issue,>> i>> can see all the results and waveforms.>> But if we change DDR2 to driver and MPC8349E to receiver (To simulate DDR2>> read situation)>> *I am getting Convergence error and lot of failures.*>>>> *Signoise Errors/Warnings*>> ERRORS:>> Simulation (DESIGN IO4 1) DESIGN IO4 1 Pulse Slow Reflection Failed>> Simulation (DESIGN IO4 1) DESIGN IO4 1 Pulse Typ Reflection Failed>> Simulation (DESIGN IO4 1) DESIGN IO4 1 Pulse Fast Reflection Failed>> WARNINGS:>> SERIOUS WARNING(SPSIMS-73): Convergence Problem in Simulation of "DESIGN>> IO4 1" stimulus Pulse.>>>> What needs to be done to this?>>>> We need one clarification:>> There are different models for MPC8349E>> Few are Io models and few are Input only models.>> During READ simulation,>> whether we need to use different model like ddr2_i_75_Ohm_term   - DDRII>> input with 75 Ohm ODT>> *or same model(*ddr2_io_0000)?>>>> Screenshot http://postimg.org/image/f6bzr3h61/>>>>>> 
Answered byferhatyaldiz 6 years 25 days
You can reduce timestep for overcoming this convergence error.You can use different ODT options for receive operation. You mustinvestigateDDRx controller chapter of your MPU manual for this.Ferhat YaldizOn Wed, Nov 5, 2014 at 3:14 AM, Mallikarjun K  wrote:> We are trying to simulate a topology.> Driver is MPC8349E> Here are the Models available for DDR2.>  ddr2_io_0000  - DDRII, 1.8v, 36 Ohm, Much Higher Z than nominal>  ddr2_io_0001  - DDRII, 1.8v, 23 Ohm, Very High Z than nominal>  ddr2_io_0011  - DDRII, 1.8v, 20 Ohm, Higher Z than nominal>  ddr2_io_0111  - DDRII, 1.8v, 18 Ohm, Nominal Z>  ddr2_io_1111  - DDRII, 1.8v, 16 Ohm, Lower Z than nominal>  ddr2_i_150_Ohm_term  - DDRII input with 150 Ohm ODT>  ddr2_i_75_Ohm_term   - DDRII input with 75 Ohm ODT>  ddr2_i_no_term       - DDRII input without ODT>> I am simply analysing one data line.> We took  ddr2_io_0000 model as driver and MT47H256M8EB-25EC as receiver.> Topology is like this> Driver(ddr2_io_0000) ----> MS1(50 Ohms, 100mils Length)---> SL1(length> varied linearly from 1000 mils to 5000 mils) ---> MS2(50 Ohms, 100mils)--->> DDR2(DQ_FULL_ODT75/50/150/No ODT_533).>> When we simulate MPC8349E as driver, i didn't get any Convergence issue,  i> can see all the results and waveforms.> But if we change DDR2 to driver and MPC8349E to receiver (To simulate DDR2> read situation)> *I am getting Convergence error and lot of failures.*>> *Signoise Errors/Warnings*> ERRORS:> Simulation (DESIGN IO4 1) DESIGN IO4 1 Pulse Slow Reflection Failed> Simulation (DESIGN IO4 1) DESIGN IO4 1 Pulse Typ Reflection Failed> Simulation (DESIGN IO4 1) DESIGN IO4 1 Pulse Fast Reflection Failed> WARNINGS:> SERIOUS WARNING(SPSIMS-73): Convergence Problem in Simulation of "DESIGN> IO4 1" stimulus Pulse.>> What needs to be done to this?>> We need one clarification:> There are different models for MPC8349E> Few are Io models and few are Input only models.> During READ simulation,> whether we need to use different model like ddr2_i_75_Ohm_term   - DDRII> input with 75 Ohm ODT> *or same model(*ddr2_io_0000)?>> Screenshot http://postimg.org/image/f6bzr3h61/>>>