Hello, I'm using altera devices for about 10 years with quartus or quartus + synplify pro. I'm currently struggling for about a month !!! on this issue: Using the same netlist from synplify pro, the same timing constraints, and doing the place and route with quartus, I can get total different results on FPGA (stratix III): fully working, or failing on first HW accesses. The IP in the FPGA uses a lot of clock gating and I think that Quartus is not doing a good timing analysis (timequest reports no timing violations and the design is fully constrained), leading to such random results. Did you ever face such problem at your place ? Metastability report in timequest reports no problem. Resets are ok. Cooling the FPGA does not change anything. I never faced such situation before. I need help ! Alex

--- Quote Start --- Hello, I'm using altera devices for about 10 years with quartus or quartus + synplify pro. I'm currently struggling for about a month !!! on this issue: Using the same netlist from synplify pro, the same timing constraints, and doing the place and route with quartus, I can get total different results on FPGA (stratix III): fully working, or failing on first HW accesses. The IP in the FPGA uses a lot of clock gating and I think that Quartus is not doing a good timing analysis (timequest reports no timing violations and the design is fully constrained), leading to such random results. Did you ever face such problem at your place ? Metastability report in timequest reports no problem. Resets are ok. Cooling the FPGA does not change anything. I never faced such situation before. I need help ! Alex --- Quote End --- Is it random per build or per download or per reset? If it is per build then what do you change to rebuild? If it is per download(of same one build) then it points to power up reset issues. If it is per reset(one download) then it is due to your reset. Try changing its duration. do you have multicycle deconstraint? if so double check them. Also check your clock signal and voltage levels.

It is random per place and route. When it fails, it always fails at the same point after several resets or re-sof. I change nothing between build. no multi cycles. Few false path but for debug ports. Voltage is ok (1.1V). Clocks are ok.

--- Quote Start --- It is random per place and route. When it fails, it always fails at the same point after several resets or re-sof. I change nothing between build. no multi cycles. Few false path but for debug ports. Voltage is ok (1.1V). Clocks are ok. --- Quote End --- If you change nothing between builds then I assume the fitting results should be more or less identical. Therefore (my guess) it is likely your problem is to do with reset functionality per se which appears at power up or afterwards. I believe the place and route variation is just coincidence of same issue. I mean some registers are not under reset. You need to check that your control signals are all under reset. You can also uncheck powerup don't care in the fitter settings so that all registers power up low(except preset ones). Finally you may add signaltap to capture the events at failure. You may find a work around if you play with the duration and release of reset until you find a stable window. also check for any floating inputs which are not driven at your development stage

This is not a reset issue, it is properly driven, synchronized and with a long duration. power up don't care is already unchecked. There is no floating inputs.

I think the report is too vague to seriously guess about the problem cause. I'm surprised about the "lot of clock gating" point. By nature of the clock networks, FPGAs are not designed to implement clock gating effectively, with the exception of those cases where clock control blocks or PLL blocks hold in reset can be utilized. Timing analysis should still work, but we don't know much about the design, see my first point.

Random results on FPGA | Altera Community

32 Replies

Altera_Forum
Honored Contributor
13 years ago
It is working fine using 91 clocks and using those settings:

set_global_assignment -name FAMILY "Stratix III"
set_global_assignment -name DEVICE EP3SL340F1760C3
set_global_assignment -name TOP_LEVEL_ENTITY wlc_ip1302_gbb5_fpga_a
set_global_assignment -name ORIGINAL_QUARTUS_VERSION 12.1
set_global_assignment -name PROJECT_CREATION_TIME_DATE "10:12:01 DECEMBER 11, 2012"
set_global_assignment -name LAST_QUARTUS_VERSION "12.1 SP1"
set_global_assignment -name PROJECT_OUTPUT_DIRECTORY output_files
set_global_assignment -name MIN_CORE_JUNCTION_TEMP 0
set_global_assignment -name MAX_CORE_JUNCTION_TEMP 85
set_global_assignment -name DEVICE_FILTER_PACKAGE FBGA
set_global_assignment -name DEVICE_FILTER_PIN_COUNT 1760
set_global_assignment -name DEVICE_FILTER_SPEED_GRADE 3
set_global_assignment -name ERROR_CHECK_FREQUENCY_DIVISOR 256
set_global_assignment -name ENABLE_INIT_DONE_OUTPUT ON
set_global_assignment -name STRATIX_JTAG_USER_CODE 20130424
set_global_assignment -name USE_CONFIGURATION_DEVICE OFF
set_global_assignment -name CRC_ERROR_OPEN_DRAIN OFF
set_global_assignment -name RESERVE_ALL_UNUSED_PINS_WEAK_PULLUP "AS INPUT TRI-STATED WITH WEAK PULL-UP"
set_global_assignment -name STRATIX_DEVICE_IO_STANDARD "3.3-V LVTTL"
set_global_assignment -name OUTPUT_IO_TIMING_NEAR_END_VMEAS "HALF VCCIO" -rise
set_global_assignment -name OUTPUT_IO_TIMING_NEAR_END_VMEAS "HALF VCCIO" -fall
set_global_assignment -name OUTPUT_IO_TIMING_FAR_END_VMEAS "HALF SIGNAL SWING" -rise
set_global_assignment -name OUTPUT_IO_TIMING_FAR_END_VMEAS "HALF SIGNAL SWING" -fall

set_global_assignment -name FITTER_EFFORT "STANDARD FIT"
set_global_assignment -name FLOW_DISABLE_ASSEMBLER OFF
set_global_assignment -name FLOW_ENABLE_IO_ASSIGNMENT_ANALYSIS OFF
set_global_assignment -name STRATIXII_OPTIMIZATION_TECHNIQUE SPEED
set_global_assignment -name TIMEQUEST_MULTICORNER_ANALYSIS ON
set_global_assignment -name SMART_RECOMPILE ON
set_global_assignment -name ENABLE_BENEFICIAL_SKEW_OPTIMIZATION ON

set_global_assignment -name VERILOG_INPUT_VERSION VERILOG_2001
set_global_assignment -name VERILOG_SHOW_LMF_MAPPING_MESSAGES OFF

set_global_assignment -name NUM_PARALLEL_PROCESSORS 2
set_global_assignment -name SYNTH_TIMING_DRIVEN_SYNTHESIS OFF
set_global_assignment -name OPTIMIZE_POWER_DURING_SYNTHESIS OFF
set_global_assignment -name OPTIMIZE_HOLD_TIMING "ALL PATHS"
set_global_assignment -name OPTIMIZE_MULTI_CORNER_TIMING ON
set_global_assignment -name OPTIMIZE_POWER_DURING_FITTING OFF
set_global_assignment -name SYNTH_GATED_CLOCK_CONVERSION ON
set_global_assignment -name PLACEMENT_EFFORT_MULTIPLIER 1
set_global_assignment -name ROUTER_EFFORT_MULTIPLIER 1
set_instance_assignment -name SLEW_RATE 3 -to *

set_global_assignment -name STATE_MACHINE_PROCESSING "ONE-HOT"
set_global_assignment -name PHYSICAL_SYNTHESIS_COMBO_LOGIC OFF
set_global_assignment -name PHYSICAL_SYNTHESIS_REGISTER_DUPLICATION OFF
set_global_assignment -name PHYSICAL_SYNTHESIS_REGISTER_RETIMING OFF
set_global_assignment -name ROUTER_LCELL_INSERTION_AND_LOGIC_DUPLICATION ON
set_global_assignment -name ROUTER_TIMING_OPTIMIZATION_LEVEL MAXIMUM
set_global_assignment -name PRE_MAPPING_RESYNTHESIS OFF
set_global_assignment -name AUTO_PACKED_REGISTERS_STRATIXII NORMAL
set_global_assignment -name ADV_NETLIST_OPT_SYNTH_WYSIWYG_REMAP OFF
set_global_assignment -name MUX_RESTRUCTURE OFF
set_global_assignment -name ROUTER_CLOCKING_TOPOLOGY_ANALYSIS ON
set_global_assignment -name SYNCHRONIZATION_REGISTER_CHAIN_LENGTH 3
set_global_assignment -name AUTO_MERGE_PLLS OFF
set_global_assignment -name POWER_USE_DEVICE_CHARACTERISTICS MAXIMUM
set_global_assignment -name POWER_PRESET_COOLING_SOLUTION "NO HEAT SINK WITH STILL AIR"
set_global_assignment -name POWER_BOARD_THERMAL_MODEL "NONE (CONSERVATIVE)"
set_global_assignment -name FITTER_AGGRESSIVE_ROUTABILITY_OPTIMIZATION AUTOMATICALLY

set_global_assignment -name SEED 2

set_global_assignment -name PHYSICAL_SYNTHESIS_EFFORT FAST
set_global_assignment -name TIMEQUEST_DO_REPORT_TIMING ON
set_global_assignment -name TIMEQUEST_DO_CCPP_REMOVAL ON

set_global_assignment -name FINAL_PLACEMENT_OPTIMIZATION AUTOMATICALLY
set_global_assignment -name ROUTER_REGISTER_DUPLICATION OFF
set_global_assignment -name ENABLE_DRC_SETTINGS OFF

set_global_assignment -name AUTO_GLOBAL_CLOCK ON

set_global_assignment -name ALLOW_POWER_UP_DONT_CARE OFF
set_global_assignment -name EXTRACT_VERILOG_STATE_MACHINES OFF
set_global_assignment -name EXTRACT_VHDL_STATE_MACHINES OFF
set_global_assignment -name INFER_RAMS_FROM_RAW_LOGIC OFF
set_global_assignment -name DSP_BLOCK_BALANCING OFF
set_global_assignment -name REMOVE_DUPLICATE_REGISTERS OFF
set_global_assignment -name AUTO_CARRY_CHAINS OFF
set_global_assignment -name AUTO_ROM_RECOGNITION OFF
set_global_assignment -name AUTO_RAM_RECOGNITION OFF
set_global_assignment -name AUTO_DSP_RECOGNITION ON
set_global_assignment -name AUTO_SHIFT_REGISTER_RECOGNITION OFF
set_global_assignment -name ALLOW_SHIFT_REGISTER_MERGING_ACROSS_HIERARCHIES OFF
set_global_assignment -name AUTO_CLOCK_ENABLE_RECOGNITION ON
set_global_assignment -name STRICT_RAM_RECOGNITION ON
set_global_assignment -name ALLOW_SYNCH_CTRL_USAGE OFF
set_global_assignment -name AUTO_RAM_BLOCK_BALANCING OFF
set_global_assignment -name BLOCK_DESIGN_NAMING QUARTUSII
set_global_assignment -name SYNTHESIS_EFFORT AUTO
set_global_assignment -name SHIFT_REGISTER_RECOGNITION_ACLR_SIGNAL OFF
set_global_assignment -name DISABLE_REGISTER_MERGING_ACROSS_HIERARCHIES OFF
set_global_assignment -name BLOCK_RAM_TO_MLAB_CELL_CONVERSION OFF
set_global_assignment -name OPTIMIZE_IOC_REGISTER_PLACEMENT_FOR_TIMING OFF
set_global_assignment -name OPTIMIZE_FOR_METASTABILITY ON

set_global_assignment -name IGNORE_LCELL_BUFFERS ON
set_global_assignment -name SYNTH_PROTECT_SDC_CONSTRAINT ON

set_global_assignment -name SYNCHRONIZER_IDENTIFICATION OFF
Altera_Forum
Honored Contributor
13 years ago
It looks like I can created the un-stability by propagating a variable clock (programmable pll)in the design (which is not selected by software).
Could it be that a variation in frequency can lead to unstability in the FPGA (I get a warning about the output of the pll not being dedicated)?
Altera_Forum
Honored Contributor
13 years ago
It's something else.
I think it is a global clock issue. If the processor gets a global clock signal, it runs fine. If not, even if timing report is clean, it fails.
Altera_Forum
Honored Contributor
13 years ago
well, it looks like the hold time analysis is a bit weak in my project,
I added a overconstraint of 0.2 ns and that seems much better.

In the sdc:

foreach_in_collection all_clocks [get_clocks *] {
set_min_delay -from $all_clocks -to $all_clocks 0.2
}
Altera_Forum
Honored Contributor
13 years ago
--- Quote Start ---
well, it looks like the hold time analysis is a bit weak in my project,
I added a overconstraint of 0.2 ns and that seems much better.

In the sdc:

foreach_in_collection all_clocks [get_clocks *] {
set_min_delay -from $all_clocks -to $all_clocks 0.2
}
--- Quote End ---

I found out that the problem was due to reset that was de-asserted internally on a wrong clock domain.
Altera_Forum
Honored Contributor
13 years ago
No, there is still another issue (
Altera_Forum
Honored Contributor
13 years ago
In the end, what is your ti, ing failure now? Setup or hold violation? Can try over constraint the hold design usingbclock uncertainty?
Altera_Forum
Honored Contributor
13 years ago
that"s the problem, there is no timing violations ^^
I"m now testing with more clock uncertainties, will see if that helps.
Altera_Forum
Honored Contributor
13 years ago
How is the timing margin?
Altera_Forum
Honored Contributor
13 years ago
Looks like a clock uncertainty margin of 0.5 ns helps.
Will see over several runs if that's true ^^

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Random results on FPGA

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