1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2 3<html> 4 5 <head> 6 <title>Making PARSE Clocks</title> 7 <link href="scripts/style.css" type="text/css" rel="stylesheet"> 8 </head> 9 10 <body> 11 <h3>How to build new PARSE clocks</h3> 12 <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> 13 <p>Prerequisites:</p> 14 <ul> 15 <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) 16 </ul> 17 <p>What to do:</p> 18 <p>Make a conversion module (libparse/clk_*.c)</p> 19 <ol> 20 <li>What ist the time code format ? 21 <ul> 22 <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: 23 <pre> 24 struct clocktime /* clock time broken up from time code */ 25 { 26 long day; 27 long month; 28 long year; 29 long hour; 30 long minute; 31 long second; 32 long usecond; 33 long utcoffset; /* in seconds */ 34 time_t utcoffset; /* true utc time instead of date/time */ 35 long flags; /* current clock status */ 36 }; 37</pre> 38 <p>Conversion is usually simple and straight forward. For the flags following values can be OR'ed together:</p> 39 <pre> 40 PARSEB_ANNOUNCE switch time zone warning (informational only) 41 PARSEB_POWERUP no synchronisation - clock confused (must set then) 42 PARSEB_NOSYNC timecode currently not confirmed (must set then) 43 usually on reception error when there is still a 44 chance the the generated time is still ok. 45 46 PARSEB_DST DST in effect (informational only) 47 PARSEB_UTC timecode contains UTC time (informational only) 48 PARSEB_LEAPADD LEAP addition warning (prior to leap happening - must set when imminent) 49 also used for time code that do not encode the 50 direction (as this is currently the default). 51 PARSEB_LEAPDEL LEAP deletion warning (prior to leap happening - must set when imminent) 52 PARSEB_ALTERNATE backup transmitter (informational only) 53 PARSEB_POSITION geographic position available (informational only) 54 PARSEB_LEAPSECOND actual leap second (this time code is the leap 55 second - informational only) 56</pre> 57 <p>These are feature flags denoting items that are supported by the clock:</p> 58 <pre> 59 PARSEB_S_LEAP supports LEAP - might set PARSEB_LEAP 60 PARSEB_S_ANTENNA supports ANTENNA - might set PARSEB_ALTERNATE 61 PARSEB_S_PPS supports PPS time stamping 62 PARSEB_S_POSITION supports position information (GPS) 63 </pre> 64 <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> 65 <p>Conversion is done in the cvt_* routine in parse/clk_*.c files. look in them for examples. The basic structure is:</p> 66 <pre> 67 struct clockformat <yourclock>_format = { 68 lots of fields for you to fill out (see below) 69 }; 70 71 static cvt_<yourclock>() 72 ... 73 { 74 if (<I do not recognize my time code>) { 75 return CVT_NONE; 76 } else { 77 if (<conversion into clockformat is ok>) { 78 <set all necessary flags>; 79 return CVT_OK; 80 } else { 81 return CVT_FAIL|CVT_BADFMT; 82 } 83 } 84</pre> 85 <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.</p> 86 <pre> 87struct clockformat 88{ 89 u_long (*input)(); 90 /* input routine - your routine - cvt_<yourclock> */ 91 u_long (*convert)(); 92 /* conversion routine - your routine - cvt_<yourclock> */ 93 /* routine for handling RS232 sync events (time stamps) - usually sync_simple */ 94 u_long (*syncpps)(); 95 /* PPS input routine - usually pps_one */ 96 void *data; 97 /* local parameters - any parameters/data/configuration info your conversion 98 routine might need */ 99 char *name; 100 /* clock format name - Name of the time code */ 101 unsigned short length; 102 /* maximum length of data packet for your clock format */ 103 u_long flags; 104 /* information for the parser what to look for */ 105}; 106</pre> 107 <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> 108 <p>In order to make your clk_*.c file usable a reference to the clockformat structure must be put into parse_conf.c.</p> 109 </ul> 110 <li>TTY setup and initialisation/configuration will be done in ntpd/refclock_parse.c. 111 <ul> 112 <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. 113 <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) 114 <pre> 115 struct clockinfo 116 { 117 u_long cl_flags; /* operation flags (io modes) */ 118 PARSE_F_PPSPPS use loopfilter PPS code (CIOGETEV) 119 PARSE_F_PPSONSECOND PPS pulses are on second 120 usually flags stay 0 as they are used only for special setups 121 122 void (*cl_poll)(); /* active poll routine */ 123 The routine to call when the clock needs data sent to it in order to 124 get a time code from the clock (e.g. Trimble clock) 125 126 int (*cl_init)(); /* active poll init routine */ 127 The routine to call for very special initializations. 128 129 void (*cl_event)(); /* special event handling (e.g. reset clock) */ 130 What to do, when an event happens - used to re-initialize clocks on timeout. 131 132 void (*cl_end)(); /* active poll end routine */ 133 The routine to call to undo any special initialisation (free memory/timers) 134 135 void *cl_data; /* local data area for "poll" mechanism */ 136 local data for polling routines 137 138 u_fp cl_rootdelay; /* rootdelay */ 139 NTP rootdelay estimate (usually 0) 140 141 u_long cl_basedelay; /* current offset - unsigned l_fp 142 fractional part (fraction) by 143 which the RS232 time code is 144 delayed from the actual time. */ 145 146 u_long cl_ppsdelay; /* current PPS offset - unsigned l_fp fractional 147 time (fraction) by which the PPS time stamp is delayed (usually 0) 148 part */ 149 150 char *cl_id; /* ID code (usually "DCF") */ 151 Refclock id - (max 4 chars) 152 153 char *cl_description; /* device name */ 154 Name of this device. 155 156 char *cl_format; /* fixed format */ 157 If the data format cann not ne detected automatically this is the name 158 as in clk_*.c clockformat. 159 160 u_char cl_type; /* clock type (ntp control) */ 161 Type if clock as in clock status word (ntp control messages) - usually 0 162 163 u_long cl_maxunsync; /* time to trust oscillator after losing synch 164 */ 165 seconds a clock can be trusted after losing synchronisation. 166 167 u_long cl_speed; /* terminal input & output baudrate */ 168 u_long cl_cflag; /* terminal io flags */ 169 u_long cl_iflag; /* terminal io flags */ 170 u_long cl_oflag; /* terminal io flags */ 171 u_long cl_lflag; /* terminal io flags */ 172 termio*.h tty modes. 173 174 u_long cl_samples; /* samples for median filter */ 175 u_long cl_keep; /* samples for median filter to keep */ 176 median filter parameters - smoothing and rejection of bad samples 177 } clockinfo[] = { 178 ...,<other clocks>,... 179 { < your parameters> }, 180 }; 181 182</pre> 183 </ul> 184 </ol> 185 <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> 186 <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> 187 <p>For questions: <a href="mailto:%20kardel@acm.org">kardel@acm.org</a>.</p> 188 <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).</p> 189 <hr> 190 <script type="text/javascript" language="javascript" src="scripts/footer.txt"></script> 191 </body> 192 193 <body></body> 194 195</html> 196