diff options
Diffstat (limited to 'html/parsenew.htm')
| -rw-r--r-- | html/parsenew.htm | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/html/parsenew.htm b/html/parsenew.htm new file mode 100644 index 000000000000..0ef60bc06002 --- /dev/null +++ b/html/parsenew.htm @@ -0,0 +1,237 @@ +<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML Strict//EN"> +<TITLE>Making PARSE Clocks</TITLE> +<h1>How to build new PARSE clocks</h1> + +<p>Here is an attempt to sketch out what you need to do in order to +add another clock to the parse driver: +Currently the implementation is being cleaned up - so not all information +in here is completely correct. Refer to the included code where in doubt. + + +<p>Prerequisites: +<ul> +<li>Does the system you want the clock connect to have the include files +termio.h or termios.h ? (You need that for the parse driver) +</ul> + + +<p>What to do: + + +<p>Make a conversion module (libparse/clk_*.c) + +<ol> +<li>What ist the time code format ? +<ul> +<li> find year, month, day, hour, minute, second, status (synchronised or +not), possibly time zone information (you need to give the offset to UTC) +You will have to convert the data from a string into a struct clocktime: +<pre> + struct clocktime /* clock time broken up from time code */ + { + long day; + long month; + long year; + long hour; + long minute; + long second; + long usecond; + long utcoffset; /* in seconds */ + time_t utcoffset; /* true utc time instead of date/time */ + long flags; /* current clock status */ + }; +</pre> + +<p>Conversion is usually simple and straight forward. For the flags following +values can be OR'ed together: +<PRE> + PARSEB_ANNOUNCE switch time zone warning (informational only) + PARSEB_POWERUP no synchronisation - clock confused (must set then) + PARSEB_NOSYNC timecode currently not confirmed (must set then) + usually on reception error when there is still a + chance the the generated time is still ok. + + PARSEB_DST DST in effect (informational only) + PARSEB_UTC timecode contains UTC time (informational only) + PARSEB_LEAPADD LEAP addition warning (prior to leap happening - must set when imminent) + also used for time code that do not encode the + direction (as this is currently the default). + PARSEB_LEAPDEL LEAP deletion warning (prior to leap happening - must set when imminent) + PARSEB_ALTERNATE backup transmitter (informational only) + PARSEB_POSITION geographic position available (informational only) + PARSEB_LEAPSECOND actual leap second (this time code is the leap + second - informational only) +</PRE> + +<p>These are feature flags denoting items that are supported by the clock: + <PRE> + PARSEB_S_LEAP supports LEAP - might set PARSEB_LEAP + PARSEB_S_ANTENNA supports ANTENNA - might set PARSEB_ALTERNATE + PARSEB_S_PPS supports PPS time stamping + PARSEB_S_POSITION supports position information (GPS) + </PRE> + + <p>If the utctime field is non zero this value will be take as + time code value. This allows for conversion routines that + already have the utc time value. The utctime field gives the seconds + since Jan 1st 1970, 0:00:00. The useconds field gives the respective + usec value. The fields for date and time (down to second resolution) + will be ignored. + + + <p>Conversion is done in the cvt_* routine in parse/clk_*.c files. look in + them for examples. The basic structure is: + +<PRE> + struct clockformat <yourclock>_format = { + lots of fields for you to fill out (see below) + }; + + static cvt_<yourclock>() + ... + { + if (<I do not recognize my time code>) { + return CVT_NONE; + } else { + if (<conversion into clockformat is ok>) { + <set all necessary flags>; + return CVT_OK; + } else { + return CVT_FAIL|CVT_BADFMT; + } + } +</PRE> + + +<p>The struct clockformat is the interface to the rest of the parse + driver - it holds all information necessary for finding the + clock message and doing the appropriate time stamping. + +<PRE> +struct clockformat +{ + u_long (*input)(); + /* input routine - your routine - cvt_<yourclock> */ + u_long (*convert)(); + /* conversion routine - your routine - cvt_<yourclock> */ + /* routine for handling RS232 sync events (time stamps) - usually sync_simple */ + u_long (*syncpps)(); + /* PPS input routine - usually pps_one */ + void *data; + /* local parameters - any parameters/data/configuration info your conversion + routine might need */ + char *name; + /* clock format name - Name of the time code */ + unsigned short length; + /* maximum length of data packet for your clock format */ + u_long flags; + /* information for the parser what to look for */ +}; +</PRE> + + +<p>The above should have given you some hints on how to build a clk_*.c + file with the time code conversion. See the examples and pick a clock + closest to yours and tweak the code to match your clock. + + + <p>In order to make your clk_*.c file usable a reference to the clockformat + structure must be put into parse_conf.c. +</ul> +<li>TTY setup and initialisation/configuration will be done in +ntpd/refclock_parse.c. +<ul> +<li>Find out the exact tty settings for your clock (baud rate, parity, +stop bits, character size, ...) and note them in terms of +termio*.h c_cflag macros. +<li>in ntpd/refclock_parse.c fill out a new the struct clockinfo element +(that allocates a new "IP" address - see comments) +(see all the other clocks for example) +<PRE> + struct clockinfo + { + u_long cl_flags; /* operation flags (io modes) */ + PARSE_F_PPSPPS use loopfilter PPS code (CIOGETEV) + PARSE_F_PPSONSECOND PPS pulses are on second + usually flags stay 0 as they are used only for special setups + + void (*cl_poll)(); /* active poll routine */ + The routine to call when the clock needs data sent to it in order to + get a time code from the clock (e.g. Trimble clock) + + int (*cl_init)(); /* active poll init routine */ + The routine to call for very special initializations. + + void (*cl_event)(); /* special event handling (e.g. reset clock) */ + What to do, when an event happens - used to re-initialize clocks on timeout. + + void (*cl_end)(); /* active poll end routine */ + The routine to call to undo any special initialisation (free memory/timers) + + void *cl_data; /* local data area for "poll" mechanism */ + local data for polling routines + + u_fp cl_rootdelay; /* rootdelay */ + NTP rootdelay estimate (usually 0) + + u_long cl_basedelay; /* current offset - unsigned l_fp + fractional part (fraction) by + which the RS232 time code is + delayed from the actual time. */ + + u_long cl_ppsdelay; /* current PPS offset - unsigned l_fp fractional + time (fraction) by which the PPS time stamp is delayed (usually 0) + part */ + + char *cl_id; /* ID code (usually "DCF") */ + Refclock id - (max 4 chars) + + char *cl_description; /* device name */ + Name of this device. + + char *cl_format; /* fixed format */ + If the data format cann not ne detected automatically this is the name + as in clk_*.c clockformat. + + u_char cl_type; /* clock type (ntp control) */ + Type if clock as in clock status word (ntp control messages) - usually 0 + + u_long cl_maxunsync; /* time to trust oscillator after loosing synch + */ + seconds a clock can be trusted after loosing synchronisation. + + u_long cl_speed; /* terminal input & output baudrate */ + u_long cl_cflag; /* terminal io flags */ + u_long cl_iflag; /* terminal io flags */ + u_long cl_oflag; /* terminal io flags */ + u_long cl_lflag; /* terminal io flags */ + termio*.h tty modes. + + u_long cl_samples; /* samples for median filter */ + u_long cl_keep; /* samples for median filter to keep */ + median filter parameters - smoothing and rejection of bad samples + } clockinfo[] = { + ...,<other clocks>,... + { < your parameters> }, + }; + +</PRE> +</ul> +</ol> + +<p>Well, this is very sketchy, i know. But I hope it helps a little bit. +The best way is to look which clock comes closest to your and tweak that +code. + +<p>Two sorts of clocks are used with parse. Clocks that automatically send +their time code (once a second) do not need entries in the poll routines because +they send the data all the time. The second sort are the clocks that need a +command sent to them in order to reply with a time code (like the Trimble +clock). + +<p>For questions: <a href="mailto: kardel@acm.org">kardel@acm.org</a>. + +<p>Please include an exact description on how your clock works. (initialisation, +TTY modes, strings to be sent to it, responses received from the clock). +<hr><p> +<a href="http://www4.informatik.uni-erlangen.de/~kardel">Frank Kardel</a> |