verilog - How to use clock gating in RTL? -
I'm going to have some trash and logical moves in my design. I do not have much experience in synthesis and location & amp; way. What is the correct way to implement clock gateing in RTL?
Example 1:
always_com starts gated_clk = clk & amp; Latch_update_en; End always_latch if (gated_clk) starts latch_data & lt; = New_data; Example 2: While doing some research about good practices in RTL clock gateing, I stumbled in one of the RTL examples. This is the reason that the above code was implemented in this way: clock_gator cg_cell (.clk (clk), .en (latch_update_en), .scan_en (scan_en_in), .gated_clk (gated_clk) ); Always_latch if (gated_clk) starts, latch_data starts
What is the purpose of using custom clock gateing cell? Does the device get a hard time in synthesis if the CLK is always "and" -a still in a compartment block with a capable signal? I feel like the special clock is a standard approach to the gated clock signal generated to use the gate cell. I am trying to understand why this is the case.
What is the correct way to implement clock gateing in RTL?
Clock gateing signal should be toggled only when the latch closes, otherwise otherwise there is a chance for combat and metastability issues. For an active high latch, toggle the falling edge of the gate signal clock should be toggle. Edge edge for active low lathes.
Normally you create an edge-sensitive flop to catch latch_update_en to prevent noise on the receiving signal.
always_ff @ (nehगेase CLK) latch_update_en & lt; = Next_latch_update_en; Always_comb gated_clk = (* clock_gating = "clk" *) CLK & amp; Latch_update_en; Always_latch if (gated_clk) latch_data & lt; = New_data; Reminder: If you only have dog behavior: the edge of the trigger flop only Master / Slave Lettuce always_latch If (CLK) sync_latch_update_en & lt; = Next_latch_update_en; Always_latch if (! Clk) latch_update_en & lt; = Sync_latch_update_en;
Does the device get a hard time in synthesis if the CLK is directly contained in the "and" always-combo block with the second capable signal?
Problems with most synthesis are straight and with a clock, it is not always intuitive how getting should be used. There are many more gates in the library to choose often in a synthesizer, each loads very different on different styles, skew, and input combinations. Although functionally similar, A & amp; B will get results of different time then B & amp; A .
Instantizing a clear cell from the Synthesizer library and possibilities of approximate behavior are narrowed. A predefined clock gateing cell has the properties used by the synthesizer. Features include timing information to balance clock tree (buffer placement in design for load and parasitic management).
Some synthesizer RTLs (eg: // synthesis attributes or (* attributes *) ) are not required to explicitly trigger a cell is. There is no standard to do this, so it refers to your user manual.
What is the purpose of using custom clock gateing cell?
The custom cell in the processing libraries is a defined defining cell, which is accompanied by time information, load balancing and other characteristics. With this information, the synthesizer knows how to add buffer delay in the clock tree or how it should be. This can be ensured that the watch does not see the clock edge before the non-connected flop gate flop.
_____ _____ in ------------- | DQ | ----- | DQ | --- out | | | | | \ | \ | | | | + - | & Gt; | & Gt; --- | & Gt; | + - | & Gt; | | | / | / | _____ | | | _____ | | ___ | CLK - + - | \ | | & Amp; ) ------------- + Balanced Clock: Sample Gate Sample Data - | ___ /
Without a guideline, a delayed flop clock can be found. Incorrect wrong data will be the reason for obtaining a sample.
_____ _____ IN ------------- | DQ | ----- | DQ | - - Outside | | | | | | | | + ---------- | & Gt; | + - | & Gt; | | | _____ | | | _____ | | ___ | CLK - + - | \ | \ | \ | | & Amp; ) --- | & Gt; | & Gt; ---- + Unlocked Clock: Sample Gate of Wrong Data - | ___ / | / | /
Comments
Post a Comment