hello everybody

I want to manually stall pipeline in a marked clock of cpu.
for this goal, which of units should be changed? (or1200_freeze, or1200_ctrl, ...)

Can i just send NOP in writeback stage?

please help me

What do you intend to achieve with the insertion of a NOP in the pipeline? Are you implementing instruction which will need to stall the processor while it performs a task which takes multiple cycles?

If so, you might want to look into the signals from the multiply/MAC unit which feed back to the unit. They provide the capability to stall the processor for an arbitrary numbers of cycles.

If not, please restate your question.

Thanks Mr Julius for your reply

I want to capture the state of the processor (Register file, ex_pc, sr) in a specific time for checkpointing. In my project no new instruction is added, but i have to get checkpoint by design a hardware unit and signaling.

Is this enough to change freeze signals assignment in the or1200_freeze?

and

how can i to observe the values of signals in simulation? i want to use modelsim for simulation, but i do not how to perform it? in orpsocv2 project can we use make file to test our programs by modelsim? if yes how can we see the waves of signals?

regards

Thanks Mr Julius

Your help was very good. I can stall the or1200 processor by setting these signals:

In or1200_freeze module:

wb_freeze and id_freeze.