New ContributorStop_at_clocks substitute in Quartus Standard
Hello,
I would like to ask if there is a substitute of the argument Stop_at_clocks (get_fanins) that exist for Quartus Pro but doesn't work for Standard Edition? I always end up with refclock instead of a PLL output.
The error I see is:
"More than 1 positional argument specified: -stop_at_clocks, clk_0"
It looks like interpretation of that argument is not implemented.
I would like to retrieve a period of an input and output clock of a synchroniser. My strategy in Quartus Pro is just to take fanin of a register No.1 and figure out a name of the clock. That's easy. I use stop_at_clocks attribute to not to obtain refclock all the time, but the output of PLL if necessary. Then I get all the clock object with the following command.
set clks [all_clocks]
After I have all the clocks in a collection I compare the clock of a register with all the clocks from the set. Based on that I can relate a clock from which I extract a period. This is supposed to modularize my bus synchroniser. Setting max and min delay should ensure correctness of all the bits.
Additional question. What is the reason to distinguish pin & pin_objects, clock & clock_objects. Can we easily convert between them? Why I cannot easily retrieve clock period information from a clock_object? The naming of the type is provided by the function:
get_object_info -type $my_reg
I followed mostly the following example:
Get Clocks Feeding a Pin:
The code that works for me in Quartus Pro 20.4 but doesn't in Quartus Standard 21.1:
top.sdc
set_time_format -unit ns -decimal_places 3
set_operating_conditions -model slow -voltage 1100 -temperature 85
create_clock -name clk_in1 -period 84.00MHz [get_ports {clk_in1}]
# Automatically constrain PLL and other generated clocks (there should be clk_in2 derived from this PLL)
derive_pll_clocks -create_base_clocks -use_net_name
# Automatically calculate clock uncertainty to jitter and other effects.
derive_clock_uncertainty
bus_synchroniser.sdc
# Get the register that I want to constrain
set kprs [get_registers {*sync_bus:*|ci_dta_r[*]}]
# Get a list of all clocks in the top-level design
set clks [all_clocks]
foreach_in_collection clk $clks {
puts [get_clock_info -name $clk]
set fanins [get_fanins -clock -stop_at_clocks $clk]
}
set cdc_period_ratio 0.95
# Match my register to two of the clocks from the lists - clock feeding the register and a clock of the output signal target.
# Iterate over synchronisation input registers
foreach_in_collection kpr $kprs {
set str1 "|Register in: "
set regIn [get_object_info -name $kpr]
# Get a list of all registers driven by each clock
set str3 "|Clock in: "
set clkIn ""
set in_period 0.00ns
set fanins [get_fanins -clock -stop_at_clocks [get_object_info -name $kpr]]
foreach_in_collection fanin $fanins {
set clkIn [get_object_info -name $fanin]
set clknet [get_pin_info -net $fanin]
foreach_in_collection clk $clks {
if {[get_object_info -name $clk] == [get_object_info -name $clknet]} {
set in_period [get_clock_info -period $clk]
}
}
}
}
Hi Pawel,
Got some ideas from software experts. Please try them and let me know if things work for you.
The following procedures take a node or a pin, and return the list of all clock targets feeding it. You should be able to modify these to make them return the clock target(s) feeding the register. You can then create a map of clock targets to clock names, so that you can find the clocks that exist on those targets. Once you have the clocks, you can simply string-compare them against each other to see if they are equivalent (since clock names are unique).
proc get_clock_targets_feeding_node { node } {
set my_clocks [list]
foreach_in_collection path [get_path -to [get_object_info -name [get_edge_info -src [get_node_info -clock_edges $node]]]] {
lappend my_clocks [get_object_info -name [get_path_info -from $path]]
}
return $my_clocks
}
proc get_clock_targets_feeding_pin { pin } {
set my_clocks [list]
foreach_in_collection path [get_path -to $pin] {
lappend my_clocks [get_object_info -name [get_path_info -from $path]]
}
return $my_clocks
}
Regards
