Lines Matching +full:echo +full:- +full:gpios

1 .. SPDX-License-Identifier: GPL-2.0
4 PPS - Pulse Per Second
22 --------
32 Carrier Detect pin) or to a parallel port (ACK-pin) or to a special
33 CPU's GPIOs (this is the common case in embedded systems) but in each
38 GPS receiver as PPS source, to obtain a wallclock-time with
39 sub-millisecond synchronisation to UTC.
43 ------------------
46 CPU GPIO-Pin as physical link to the signal, I encountered a deeper
56 purpose GPIO line. In this case even basic file-related functionality
72 ------------------------------
76 the USB stack. Users have reported clock instability around +-1ms when
90 --------------
101 	    .echo         = pps_ktimer_echo,
129 The same function may also run the defined echo function
133 Please see the file drivers/pps/clients/pps-ktimer.c for example code.
137 -------------
147    $ ls -F /sys/class/pps/pps0/
149    clear      echo       name       power/     uevent
161  * echo: reports if the PPS source has an echo function or not;
172 -----------------------
175 the pps-ktimer driver (see the client subsection in the PPS configuration menu)
176 and the userland tools available in your distribution's pps-tools package,
177 http://linuxpps.org , or https://github.com/redlab-i/pps-tools.
179 Once you have enabled the compilation of pps-ktimer just modprobe it (if
182    # modprobe pps-ktimer
190    source 0 - assert 1186592699.388832443, sequence: 364 - clear  0.000000000, sequence: 0
191    source 0 - assert 1186592700.388931295, sequence: 365 - clear  0.000000000, sequence: 0
192    source 0 - assert 1186592701.389032765, sequence: 366 - clear  0.000000000, sequence: 0
195 This is available in the pps-tools repository mentioned above.
199 ----------
205 To do so the class pps-gen has been added. PPS generators can be
229 ------------------------
233     $ ls /sys/class/pps-gen/
234     pps-gen0/  pps-gen1/  pps-gen2/
239     $ ls -F /sys/class/pps-gen/pps-gen0/
244     $ echo 1 > /sys/class/pps-gen/pps-gen0/enable
247 ------------------------
258 	1	STROBE	  *------     *
267 	10	ACK	  *     ------*
275 	18-25	GND	  *-----------*
277 Please note that parallel port interrupt occurs only on high->low transition,