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GLAST/LAT > DAQ and FSW > FSW > Doxygen Index > THS / V1-0-5

Constituent: ths     Tag: linux-gcc

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THS_gem.c File Reference

Time Hack Services. More...

#include "PBS/PBS.h"
#include "PBS/TASK.h"
#include "PBS/TMR.h"
#include "PBI/Endianness.h"
#include "LCBD/LCBD.h"
#include "LCBD/LCBD_pci.h"
#include "LEM/defs.h"
#include "LEM/decode.h"
#include "LEM/encode.h"
#include "LEM/encode_structs.h"
#include "LEM/cli.h"
#include "MSG/MSG_pubdefs.h"
#include "THS/THS_msgs.h"
#include "THS_prvdefs.h"
#include <stdio.h>

Include dependency graph for THS_gem.c:

Functions
WCT_time	THS_gemAbsTimeEvent (int gemStrobeIn, int gemClk)
	Calculate absolute time for event from strobe and clk provided with event (20MHz clk).
unsigned int	THS_gemInit (int siu)
	Inits the TimeHackService module.
unsigned int	THS_gemWait ()
	Start the TimeHackService module.
unsigned int	THS_gemGetTableInfo (int count, unsigned int *gemStrobe, LSU_factors *Kgem)
	get info from hack table
unsigned int	THS_gemCalcClkDiff (unsigned int clk, unsigned int prevClk)
	calculate diff between clks assuming 25 bit clock
void	THS_gemIsr (unsigned int absTimeSec, int newTimetone)
	interrupt routine for gem specfic time hack
unsigned int	THS_gemSetWarning (unsigned int expectedClkHz, unsigned int expectedDeltaClkHz)
	Set range for gem clock warning messages.
void	THS_gemSetTable (WCT_time absTimeSec, unsigned int gemStrobeIn, LSU_factors Kgem)
	Set a single entry in the gem hack table.

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Detailed Description

Time Hack Services.

Author:

Ed Bacho -- ebacho@slac.stanford.edu

This module works from within THS.c to control the GEM time hack.

This module handles calculation of absolute time using the "time hack" for the clk in the GEM (GASU).

The absolute (or true) time is provided once a second through a combination of a 1PPS (1 pulse per sec) hardware pulse and a time tone message ("at the tone the time will be") that preceeds it. The time provided in the time tone message from the scapecraft is in microSec since 1/1/2001. Hence the clock value is adjusted each second to account for clock counter drift from GEM clock.

The basic functions provided to application programs are:

• convert a 20 MHz bases clkCOunter (from GEM) value into absoluteTime

Inputs:

• time tone message every sec (500-800 mSec before pulse) giving next absTime
• HW 1PPS pulse every sec from GASU (although originates from spacecraft)

Outputs:

• convert time from event into absTIme using THS_gemAbsTimeEvent

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Function Documentation

WCT_time THS_gemAbsTimeEvent (  int  gemStrobeIn, int  gemClk )

Calculate absolute time for event from strobe and clk provided with event (20MHz clk). Parameters: gemStrobeIn  stobe counter from GEM from event data gemClk  clk counter from GEM from event data Returns: 64b value of number of nanoSec since 1/1/2001 This routine takes the stobe and clk values from the GEM (part of event data) and converts it to an absolute time. Since this value is calulated through a table saved for the last N secs, it is only valid for the last N secs else will error and retun 0.

Here is the call graph for this function:

unsigned int THS_gemCalcClkDiff (  unsigned int  clk, unsigned int  prevClk )

calculate diff between clks assuming 25 bit clock Parameters: clk  latest gem clk value prevClk  previous gem clock value Returns: difference between clk values

unsigned int THS_gemGetTableInfo (  int  count, unsigned int *  gemStrobe, LSU_factors *  Kgem )

get info from hack table Parameters: count  count value from gemStrobe, this is a 7 bit index into table gemStrobe  gemStrobe register value for this Kgem  ptr to extrapolation constants struct to fill Returns: absolute time value at PPS in sec

unsigned int THS_gemInit (  int  siu  )

Inits the TimeHackService module. Parameters: siu  1=SIU(=commander on cmd/response), 0=EPU Returns: status This routine does basic init for gem specific THS and requires only a few modules to be init (PBS,MSG, ??). It is called from THS.c. Howver, it will not be fully operation till is has received timetone and PPS interrupt. THS_gemWait() can be used to wait for this state.

void THS_gemIsr (  unsigned int  absTimeSec, int  newTimetone )

interrupt routine for gem specfic time hack Parameters: absTimeSec  absolute time at PPS newTimetone  1=indicates absTimeSec is real, 0=indicates absTimeSec is estimated Returns: nothing Interrupt routine connected to 1PPS input. This should be called from ThsIsr(). This is first half of processing to put a new entry into the time table. Other half is callback form LCB routine to read gem register.

void THS_gemSetTable (  WCT_time  absTimeSec, unsigned int  gemStrobeIn, LSU_factors  Kgem )

Set a single entry in the gem hack table. Parameters: absTimeSec  gemStrobeIn  Kgem  Returns: none On SIU, this will be called within callback from the GEM read started by the PPS interrupt. The callback will also send this info on to the EPu's On EPUs, this will be called as the results of a message from the SIU with this information.

unsigned int THS_gemSetWarning (  unsigned int  expectedClkHz, unsigned int  expectedDeltaClkHz )

Set range for gem clock warning messages. Parameters: expectedClkHz  - expected clock in Hz, <=0 uses default of 20MHz expectedDeltaClkHz  - expected delta clk in Hz, <0 uses default of 1% of clock Returns: status

unsigned int THS_gemWait (   )

Start the TimeHackService module. Returns: status Wait for THS to become full operational after THS_init(). This routines requires that most of the software is operational. This includes LCB driver, 1553 driver, and time tone messages from the scapecraft enabled. Since this module requires a timeTOne message from the spacecraft it can take up to 2 sec to return. The sequence is: THS_gemInit(); start up bunch of things including LCB driver Sw to call THS_timeTone() every second as result of message from spacecraft Hw to cause PPS interrupt every second THS_gemWait() (this routine waits till received first THS_gemTimeTone() followed by PPS interrupt)

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