Date: Sun, 22 Apr 2018 09:05:13 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 227687] PPS echo pulse on ppbus too short Message-ID: <bug-227687-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D227687 Bug ID: 227687 Summary: PPS echo pulse on ppbus too short Product: Base System Version: 11.1-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: lukas@fridolin.com PPS echo signals are not detectable on the parallel port. The irq handler in ppbus/pps.c creates the echo pulse by setting AUTOFEED, handling the pulse = and immediately unsetting AUTOFEED. The "handling the pulse" phase is not long enough to create a usable echo pulse. Adding a DELAY of 100ms before disabl= ing the bit creates good pulses, however this is not a feasible solution in an interrupt handler. Fix: Add a delay (maybe 100ms) before disabling the AUTOFEED bit. How-To-Repeat: Connect a PPS source (e.g. GPS receiver, signal generator) via the parallel port (pin 10). Set PPS_ECHOASSERT (with pps-api utility in ntp). Try to read the echo on pin 14 (e.g. with oscilloscope, LED, GPS receiver...). --=20 You are receiving this mail because: You are the assignee for the bug.=
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