Date: Tue, 22 Mar 2016 22:09:30 +0100 From: =?utf-8?Q?Peter_Ankerst=C3=A5l?= <peter@pean.org> To: Ian Lepore <ian@freebsd.org> Cc: freebsd-stable@freebsd.org, Karl Denninger <karl@denninger.net> Subject: Re: PPS input on a generic GPIO pin on Raspberry Pi. Message-ID: <13112D17-335A-4372-AEF9-ADAA2D89337E@pean.org> In-Reply-To: <EDF36350-65A9-4DB8-886E-6BCD852F2CE6@pean.org> References: <8C90C80B-AC5F-4B12-8E84-84193B8C55C4@pean.org> <56D9BDB6.6040903@denninger.net> <1457114408.13785.150.camel@freebsd.org> <EDF36350-65A9-4DB8-886E-6BCD852F2CE6@pean.org>
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--Apple-Mail=_94C144CC-ABFD-4122-A232-D8130A367C85 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On 05 Mar 2016, at 07:54, Peter Ankerst=C3=A5l <peter@pean.org> wrote: >>>>=20 >>> GPIO is supported on the Pi, I'm using it on 11-Current on my home >>> control software to drive relays on my pool hardware (e.g. valves, >>> heater, VFD motor drive, etc) and it is working very well. I don't >>> believe tapping into that at the kernel level to expose a pps signal >>> (e.g. on /dev/pps or something of the like) would be very difficult >>> at >>> all, since the low-level driver capability is already present. >>>=20 >>> If I get some free time I'll dig around a bit and see if I can = cobble >>> something up. It's of some interest to me as well since I have a = GPS >>> clock here that currently talks to a serial port on an Intel-based >>> machine and being able to move that to a $35 "appliance" for NTP >>> using >>> the Adafruit setup looks sort of attractive given that the Pi plus >>> the >>> module would be under $100 all-in. >>=20 >> Don't "cobble something up" just yet... there is "a right way" to fix >> this, which is a generic gpio-pps driver. The problem is that it >> requires support from the new INTRNG, and the rpi hasn't been = converted >> to that yet. I'm checking around to see if someone has done the >> conversion for rpi and it just hasn't been reveiwed/committed yet; if >> not, I guess I'll try to do it myself. >>=20 >> Writing the actual gpio-pps driver will be pretty quick and easy once >> we have the intrng support, I think it'll take me a couple hours. >>=20 Any new here? Would be really nice to test this on the PI. > Oh, so there is hope. Thanks for looking into it.=20 >=20 > Im not a programmer myself but im willing to help if I can.=20 >=20 >> Also, FYI, another option with PPS is to use a usb-serial adapter and >> feed the PPS in on the CTS or DCD pin. I tested that on rpi a few >> months ago and it worked fine. There's surpisingly little jitter = even >> when the usb bus is heavily loaded with other traffic such as disk or >> network IO. >>=20 > Yes that was going to be my plan B. Good to know that it works. >=20 > /Peter.=20 --Apple-Mail=_94C144CC-ABFD-4122-A232-D8130A367C85 Content-Disposition: attachment; filename=smime.p7s Content-Type: application/pkcs7-signature; name=smime.p7s Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIL0TCCBeIw ggPKoAMCAQICEGunin0K14jWUQr5WeTntOEwDQYJKoZIhvcNAQELBQAwfTELMAkGA1UEBhMCSUwx FjAUBgNVBAoTDVN0YXJ0Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmlj YXRlIFNpZ25pbmcxKTAnBgNVBAMTIFN0YXJ0Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MB4X DTE1MTIxNjAxMDAwNVoXDTMwMTIxNjAxMDAwNVowdTELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0 YXJ0Q29tIEx0ZC4xKTAnBgNVBAsTIFN0YXJ0Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MSMw IQYDVQQDExpTdGFydENvbSBDbGFzcyAxIENsaWVudCBDQTCCASIwDQYJKoZIhvcNAQEBBQADggEP ADCCAQoCggEBAL192vfDon2D9luC/dtbX64eG3XAtRmvmCSsu1d52DXsCR58zJQbCtB2/A5uFqNx WacpXGGtTCRk9dEDBlmixEd8QiLkUfvHpJX/xKnmVkS6Iye8wUbYzMsDzgnpazlPg19dnSqfhM+C 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