[ntp:questions] More than one PPS source on Raspberry Pi?

Link, Ken Ken.Link at osii.com
Mon Dec 4 20:06:20 UTC 2017

I've always thought having multiple PPS sources on a single machine wouldn't work because the PPS interrupts would occur at the same time, causing random offsets and jitter to show up on the PPS sources since the interrupts would be queued in an essentially random order and processed sequentially.

Is it different for the Raspberry Pi?

Open Systems International, Inc.

Ken Link
Software Development

4101 Arrowhead Drive
Medina, Minnesota 55340-9457
Phone: 763 551 0559
Fax: 763 551 0750
Email: Ken.Link at osii.com
Website: www.osii.com

-----Original Message-----
From: questions [mailto:questions-bounces+klink=osii.com at lists.ntp.org] On Behalf Of Frank Wayne
Sent: Monday, December 04, 2017 10:35 AM
To: questions at lists.ntp.org
Subject: [ntp:questions] More than one PPS source on Raspberry Pi?

Has anyone tried to use more than one PPS source at the same time on a Raspberry Pi? The device tree overlay pps-gpio does not seem to support more than one instance. That is, if my config.txt specifies two instances of pps-gpio for different GPIO pins, only /dev/pps0 is created.

The documentation for pps_gpio is limited or missing, and the Raspberry Pi forum and the LinuxPPS list have not helped.

If pps-gpio cannot do it, is there another way to get PPS devices for Raspbian or another OS that will run on a Pi?

Frank Wayne
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