| uart.4 (286591) | uart.4 (293781) |
|---|---|
| 1.\" 2.\" Copyright (c) 2003 Marcel Moolenaar 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" --- 9 unchanged lines hidden (view full) --- 18.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" | 1.\" 2.\" Copyright (c) 2003 Marcel Moolenaar 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" --- 9 unchanged lines hidden (view full) --- 18.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" |
| 26.\" $FreeBSD: head/share/man/man4/uart.4 286591 2015-08-10 20:08:09Z ian $ | 26.\" $FreeBSD: head/share/man/man4/uart.4 293781 2016-01-12 18:42:00Z ian $ |
| 27.\" | 27.\" |
| 28.Dd August 10, 2015 | 28.Dd December 9, 2015 |
| 29.Dt UART 4 30.Os 31.Sh NAME 32.Nm uart 33.Nd driver for Universal Asynchronous Receiver/Transmitter (UART) devices 34.Sh SYNOPSIS 35.Cd "device uart" 36.Pp --- 118 unchanged lines hidden (view full) --- 155The 156.Nm 157driver can capture PPS timing information as defined in RFC 2783. 158The API, accessed via 159.Xr ioctl 8 , 160is available on the tty device. 161To use the PPS capture feature with 162.Xr ntpd 8 , | 29.Dt UART 4 30.Os 31.Sh NAME 32.Nm uart 33.Nd driver for Universal Asynchronous Receiver/Transmitter (UART) devices 34.Sh SYNOPSIS 35.Cd "device uart" 36.Pp --- 118 unchanged lines hidden (view full) --- 155The 156.Nm 157driver can capture PPS timing information as defined in RFC 2783. 158The API, accessed via 159.Xr ioctl 8 , 160is available on the tty device. 161To use the PPS capture feature with 162.Xr ntpd 8 , |
| 163symlink the tty device to | 163symlink the tty callout device 164.Va /dev/cuau? 165to |
| 164.Va /dev/pps0. 165.Pp 166The 167.Va hw.uart.pps_mode 168tunable configures the PPS capture mode for all uart devices; 169it can be set in 170.Xr loader.conf 5 . 171The 172.Va dev.uart.0.pps_mode 173sysctl configures the PPS capture mode for a specific uart device; 174it can be set in 175.Xr loader.conf 5 176or 177.Xr sysctl.conf 5 . | 166.Va /dev/pps0. 167.Pp 168The 169.Va hw.uart.pps_mode 170tunable configures the PPS capture mode for all uart devices; 171it can be set in 172.Xr loader.conf 5 . 173The 174.Va dev.uart.0.pps_mode 175sysctl configures the PPS capture mode for a specific uart device; 176it can be set in 177.Xr loader.conf 5 178or 179.Xr sysctl.conf 5 . |
| 180.Pp |
|
| 178The following capture modes are available: 179.Bl -tag -compact -offset "mmmm" -width "mmmm" | 181The following capture modes are available: 182.Bl -tag -compact -offset "mmmm" -width "mmmm" |
| 180.It 0 | 183.It 0x00 |
| 181Capture disabled. | 184Capture disabled. |
| 182.It 1 | 185.It 0x01 |
| 183Capture pulses on the CTS line. | 186Capture pulses on the CTS line. |
| 184.It 2 185Capture pulses on the DCD line (default). | 187.It 0x02 188Capture pulses on the DCD line. |
| 186.El | 189.El |
| 190.Pp 191The following values may be ORed with the capture mode to configure 192capture processing options: 193.Bl -tag -compact -offset "mmmm" -width "mmmm" 194.It 0x10 195Invert the pulse (RS-232 logic low = ASSERT, high = CLEAR). 196.It 0x20 197Attempt to capture narrow pulses. 198.El 199.Pp 200Add the narrow pulse option when the incoming PPS pulse width is small 201enough to prevent reliable capture in normal mode. 202In narrow mode the driver uses the hardware's ability to latch a line 203state change; not all hardware has this capability. 204The hardware latch provides a reliable indication that a pulse occurred, 205but prevents distinguishing between the CLEAR and ASSERT edges of the pulse. 206For each detected pulse, the driver synthesizes both an ASSERT and a CLEAR 207event, using the same timestamp for each. 208To prevent spurious events when the hardware is intermittently able to 209see both edges of a pulse, the driver will not generate a new pair of 210events within a half second of the prior pair. 211Both normal and narrow pulse modes work with 212.Xr ntpd 8 . 213.Pp 214Add the invert option when the connection to the uart device uses TTL 215level signals, or when the PPS source emits inverted pulses. 216RFC 2783 defines an ASSERT event as a higher-voltage line level, and a CLEAR 217event as a lower-voltage line level, in the context of the RS-232 protocol. 218The modem control signals on a TTL-level connection are typically 219inverted from the RS-232 levels. 220For example, carrier presence is indicated by a high signal on an RS-232 221DCD line, and by a low signal on a TTL DCD line. 222This is due to the use of inverting line driver buffers to convert between 223TTL and RS-232 line levels in most hardware designs. 224Generally speaking, a connection to a DB-9 style connector is an RS-232 225level signal at up to 12 volts. 226A connection to header pins or an edge-connector on an embedded board 227is typically a TTL signal at 3.3 or 5 volts. |
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| 187.Sh FILES 188.Bl -tag -width ".Pa /dev/ttyu?.init" -compact 189.It Pa /dev/ttyu? 190for callin ports 191.It Pa /dev/ttyu?.init 192.It Pa /dev/ttyu?.lock 193corresponding callin initial-state and lock-state devices 194.Pp --- 20 unchanged lines hidden --- | 228.Sh FILES 229.Bl -tag -width ".Pa /dev/ttyu?.init" -compact 230.It Pa /dev/ttyu? 231for callin ports 232.It Pa /dev/ttyu?.init 233.It Pa /dev/ttyu?.lock 234corresponding callin initial-state and lock-state devices 235.Pp --- 20 unchanged lines hidden --- |