Sunday, 2019-02-03

*** tpb has joined #yosys00:00
*** emeb has left #yosys00:12
*** gsi_ has joined #yosys02:35
*** gsi__ has quit IRC02:38
*** _whitelogger has quit IRC03:31
*** _whitelogger has joined #yosys03:33
*** _whitelogger has quit IRC03:40
*** _whitelogger has joined #yosys03:42
*** _whitelogger has quit IRC03:52
*** _whitelogger has joined #yosys03:54
*** lutsabound has quit IRC03:58
*** pie__ has joined #yosys04:43
*** pie___ has quit IRC04:47
*** chaseemory has quit IRC04:58
*** cr1901_modern has quit IRC05:28
*** cr1901_modern has joined #yosys05:43
*** rohitksingh has joined #yosys05:43
*** _whitelogger has quit IRC06:01
*** _whitelogger has joined #yosys06:03
*** leviathanch has joined #yosys06:08
*** rohitksingh has quit IRC06:14
*** _whitelogger has quit IRC06:40
*** _whitelogger has joined #yosys06:42
*** emeb_mac has quit IRC07:36
*** leviathanch has quit IRC07:55
*** seldridge has quit IRC08:32
*** rohitksingh has joined #yosys08:43
*** m4ssi has joined #yosys08:51
*** rohitksingh has quit IRC09:18
*** keesj has joined #yosys09:37
*** m4ssi has quit IRC09:42
*** rohitksingh has joined #yosys09:54
*** leviathanch has joined #yosys10:01
*** rohitksingh has quit IRC10:05
*** rohitksingh has joined #yosys10:38
*** citypw has quit IRC10:39
*** ZipCPU has joined #yosys10:45
*** citypw has joined #yosys10:52
*** rohitksingh has quit IRC11:13
*** jevinskie has joined #yosys11:23
*** tmeissner has joined #yosys12:08
*** dpiegdon has joined #yosys14:18
dpiegdonhi there!14:18
*** m4ssi has joined #yosys14:19
dpiegdoni have been playing around with ringoscillators, and found a working example from clifford, at .14:25
tpbTitle: handicraft - Revision 2994: /2015/ringosc (at
dpiegdonI was able to get this running with arachnepnr easily,14:25
dpiegdonbut on nextpnr, which is timing driven, I always get the error: ERROR: timing analysis failed due to presence of combinatorial loops, incomplete specification of timing ports, etc.14:25
dpiegdonwhich makes sense, I guess. but is there a way to tell nextpnr to ignore timing here? or alltogether?14:26
dpiegdon(I have tried --no-tmdriv)14:26
*** lutsabound has joined #yosys14:39
daveshahdpiegdon: use --force14:43
dpiegdondaveshah: ok, then the error is reduced to a warning, but no output file is generated.14:48
daveshahWhat is your full command line?14:49
dpiegdon nextpnr-ice40 --no-tmdriv --force --hx1k --package tq144 --pcf icestick.pcf --json $<14:50
dpiegdoni have uploaded my example to
tpbTitle: GitHub - dpiegdon/ringoscillator: FPGA ringoscillator example. Originally taken from (at
daveshahYou need --asc output.asc to create any output14:52
dpiegdondamn - copy and paste error14:56
dpiegdonyes, that works. ringing at 322MHz :)14:58
*** brasilino has joined #yosys15:20
MoeIcenowyby the way is it a way to evalulate the frequency of such a ring oscillator?15:35
MoeIcenowycan icetime do it?15:35
sorearwith the icetime database it is possible to produce a conservative lower limit for the frequency (upper bound on delay of the closed-loop path)15:37
sorearring oscillators are very sensitive to things like temperature (and are frequently used as sensors)15:37
soreara more sophisticated timing analysis (for hold times) would also give you a lower bound on the delay → upper limit for the frequency over the operating voltage/temperature range15:38
*** m4ssi has quit IRC15:41
*** fsasm has joined #yosys15:54
dpiegdonbut icetime does not produce valid results here. neither for nextpnr nor for arachnepnr. it *did* produce some valid results for an earlier example. i am going to look into this a bit.15:55
dpiegdonso for the original version from clifford, icetime shows the (~correct) value of 8.92 MHz. but only when using arachnepnr, not for nextpnr. also when reducing the delay line, the value is rougly the lower bound, as described by sorear.15:59
dpiegdonbut when i strip the example to only the ring oscillator (remove freq counter and control), icetime is clueless and shows 0MHz.16:00
dpiegdonthe oscillator *does* work, though16:00
dpiegdonso i assume icetime does somehow uses the freq-counter logic loop to count the generated frequency.16:04
*** emeb_mac has joined #yosys16:12
*** seldridge has joined #yosys16:39
*** harryinashed has joined #yosys17:11
*** harryinashed has quit IRC17:19
*** harryinashed_ has joined #yosys17:22
*** fsasm_ has joined #yosys17:22
*** harryinashed_ has quit IRC17:23
*** harryina_ has joined #yosys17:23
*** fsasm has quit IRC17:24
*** harryina_ has quit IRC17:24
*** harryina_ has joined #yosys17:25
*** harryina_ has left #yosys17:26
*** harryina_ has joined #yosys17:26
*** harryina_ has quit IRC17:27
*** seldridge has quit IRC17:43
*** tmeissner has quit IRC17:51
*** brasilino has quit IRC18:04
*** leviathanch has quit IRC18:43
*** emeb_mac has quit IRC19:08
*** emeb has joined #yosys19:24
*** dpiegdon has quit IRC20:21
*** dpiegdon has joined #yosys20:25
*** dpiegdon has quit IRC20:44
*** cr1901_modern has quit IRC21:23
*** chaseemory has joined #yosys21:55
*** fsasm_ has quit IRC22:02
*** s_frit has quit IRC22:45
*** cr1901_modern has joined #yosys22:45
*** s_frit has joined #yosys22:45

Generated by 2.13.1 by Marius Gedminas - find it at!