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Ixiasoft
Removing Initial Power-Up Conditions
Intel recommends you do not use initial power-up conditions in your RTL. Always reset the design into a known state.
- Explicitly specify initial conditions in the RTL:
reg q = 1’b1; // q has a default value of ‘1’ always@(posedge clk) begin q <= d; end
Registers without resets may also have initial conditions. By default, Quartus® Prime determines their FF power-up values automatically.
- Turn this setting off and force Quartus® Prime to set all uninitialized registers to 0 at power up by using the following global assignment:
set_global_assignment ALLOW_POWER_UP_DONT_CARE OFFGenerally, Intel does not recommend this setting because it can hinder register retiming.
- Instead of using a global assignment, target areas of the design to drop automatically generated initial conditions with:
set_instance_assignment IGNORE_REGISTER_POWER_UP_INITIALIZATION ON -to <instance name>