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Datum bc630AT, User Manual

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OPERATION AND SOFTWARE INTERFACE

Datum Inc

bc630AT Real Time Clock Module

3-15

When scaled by the factor on the bottom of the previous page, the subsecond count will always vary
between 0 and 2E6-1, giving an accurate number of 0.5 

:

sec counts.  This methodology allows the user

to completely remove the effects of the bc630AT crystal clock frequency offset and aging.

The user may also simply divide the subsecond count by the factor (2E6 + (Time Code Period -
33920)) to produce a real number which varies between 0.0000000 and 0.9999995.
The programming examples in Section 6 provide some useful data structures and algorithms for working
with the subsecond count and Time Code Period values.

3.6  XT/AT BUS INTERRUPTS

The bc630AT interrupts the XT/AT computer by writing a value to the Interrupt register.  (Refer to
section 3.1.3.)  When this value is written, the jumper selected interrupt (IRQ3-7, IRQ10-12 or
IRQ14-15) is pulled high.  The interrupt is cleared by reading the interrupt register.  The host PC can
use the interrupt feature in a polled mode by clearing the interrupt register and polling for the respective
interrupt value.  Polling rates must not exceed 500 kHz.

3.7  REAL TIME CLOCK IC

The bc630AT has an independent battery backed Real Time Clock (RTC) IC which maintains time
during power down of the XT/AT computer.  The RTC IC time can be set and requested with the 'Set
RTC IC Time', 'Request RTC IC Time' and 'Synchronize RTC IC' commands.  The RTC IC maintains
time with month/day/year, hour/minutes/seconds and day of week format.  As an option in the Time
Code Format Select register, the RTC IC can be selected for decoding by the bc630AT and read with
microsecond precision through the standard Time Request commands.

3.7.1  REQUESTING TIME FROM THE RTC IC

Command 'Request RTC Time' retrieves the time of day directly from the independent RTC IC and
loads it into the Data Address Space.  The time is in month/year/day format and has a resolution of one
second. 

3.7.2  DECODING THE RTC IC TIME WITH MICROSECOND RESOLUTION

The bc630AT Real Time Clock Module can optionally supply time with microsecond precision without
an external time code.  This is accomplished by selecting the battery backed RTC IC for decoding in
the TCSEL register (See Section 3.1.3) followed by an 'Initialize' command.  The bc630AT now
retrieves the time from the battery backed RTC IC.  The battery backed RTC IC disciplines the
bc630AT clock with its 1PPS output.  All bc630AT features are available in this mode.

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Summary of Contents for bc630AT

Page 1: ...utilized and idle equipment along with credit for buybacks and trade ins Custom engineering so your equipment works exactly as you specify Critical and expedited services Leasing Rentals Demos In stock Ready to ship TAR certified secure asset solutions Expert team I Trust guarantee I 100 satisfaction All trademarks brand names and brands appearing herein are the property of their respective owners...

Page 2: ...bc630AT Real Time Clock Module User s Guide Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 3: ...on with microsecond precision Decodes commonly used time code formats IRIG B IRIG A NASA 36 and 2137 Master Slave operation allows digital synchronization of multiple bc630AT s Time base can be synchronized to external 1PPS or 1 5 10 MHz reference frequency Continues to provide time flywheels during loss of the external time code source Battery backed Real Time Clock maintains settable time during...

Page 4: ...0AT also incorporates a battery backed real time clock IC which maintains settable time during power loss and can be synchronized to an external time code signal The real time clock can also be decoded with microsecond precision The operation of the bc630AT is controlled by sixteen 8 bit registers written and read by the host XT AT computer These registers are used for defining the time source the...

Page 5: ... Power 5VDC 500mA TTL CMOS Input Signals Event Capture TTL CMOS positive or negative edge triggered 50ns min width 500 µs min period TTL Output Signals 1 Pulse Per Second TTL CMOS positive edge on time Heartbeat Pulse TTL CMOS positive edge on time RS 422 Input Output Signals 1PPS 1PPS 1PPS positive edge on time Serial Time Mssg TX RX TX RX 9600 Baud 8 bits 1 stop bit no parity TX compatible with ...

Page 6: ...formats were developed one for each agency involved During the early 1960 s the InterRange Instrumentation Group IRIG promoted a series of standard time code formats now loosely referred to as IRIG Time Codes The bc630AT decodes two of these formats IRIG A and IRIG B More complete details on these and other time code formats is available free of charge on request from Datum Inc in the form of the ...

Page 7: ...ion of using the additional interrupts found on the AT bus Therefore the bc630AT can be utilized in an XT computer with complete functionality and performance with the exception of a lower number of interrupt selections Physically the bc630AT mounts in either an XT or AT type computer In the case of the XT the AT s second connector is not accessed resulting in a lower number of interrupt selection...

Page 8: ...en A3 A0 are 0 Figure 2 1 DIP Switch SW1 Address Bit A9 A8 A7 A6 A5 A4 SW1 Switch To select a base address set each of the 6 DIP switches to the ON same as CLOSED or OFF same as OPEN position Setting a DIP switch to the ON position selects a logical 0 for that address bit and the OFF position selects a logical 1 In an AT computer the base address can be set in the range of 100H 3F0H In an XT compu...

Page 9: ... OFF 0 0 0 0 1E0H ON OFF OFF OFF OFF ON 0 0 0 0 1F0H ON OFF OFF OFF OFF OFF 0 0 0 0 Table 2 2 PC Bus Base Address Selection SW1 Base Addr S1 A9 S2 A8 S3 A7 S4 A6 S5 A5 S6 A4 A3 A2 A1 A0 200H OFF ON ON ON ON ON 0 0 0 0 210H OFF ON ON ON ON OFF 0 0 0 0 220H OFF ON ON ON OFF ON 0 0 0 0 230H OFF ON ON ON OFF OFF 0 0 0 0 240H OFF ON ON OFF ON ON 0 0 0 0 250H OFF ON ON OFF ON OFF 0 0 0 0 260H OFF ON ON ...

Page 10: ... OFF OFF OFF ON OFF ON 0 0 0 0 3B0H OFF OFF OFF ON OFF OFF 0 0 0 0 3C0H OFF OFF OFF OFF ON ON 0 0 0 0 3D0H OFF OFF OFF OFF ON OFF 0 0 0 0 3E0H OFF OFF OFF OFF OFF ON 0 0 0 0 3F0H OFF OFF OFF OFF OFF OFF 0 0 0 0 2 2 INSTALLATION PROCEDURE To install the bc630AT module in your computer chassis 1 Remove the computer chassis cover 2 Select a vacant expansion slot and remove the blank rear panel bracke...

Page 11: ...el shift time codes 630DEMO2 EXE General Purpose Demo Program for all time sources time code types and features of the bc630AT 630CODE SYS Device drivers that when installed replace the usual clock driver of 630RTC SYS the PC with the bc630AT Instructions on the use of these programs is contained in the diskette file README DOC At the DOS prompt simply type README Artisan Technology Group Quality ...

Page 12: ...ister The value of each register following a power on or software reset is shown A value of indicates that the register contents are undefined A label for each register is listed as is a brief description of the register s function 3 1 1 CONTROL REGISTERS The Control Registers govern the operation of the bc630AT To control the operation of the bc630AT first write the appropriate values to the cont...

Page 13: ...me Code 0 0 1 1 2137 Modulated Time Code 0 1 0 0 Battery Backed Real Time Clock IC 0 1 0 1 bc630AT Master 0 1 1 0 NASA 36 Modulated Time Code 0 1 1 1 IRIG B DC Level Shift Time Code 1 0 0 0 IRIG A DC Level Shift Time Code 1 0 0 1 NASA 36 DC Level Shift Time Code 1 0 1 0 External 1PPS 1 0 1 1 External 1 5 10 MHz Frequency TSTAT1 TSTAT0 Time Code Tracking Status 00 time code present 01 flywheeling t...

Page 14: ...onsible for clearing the flag 3 1 3 TIME CODE SELECT REGISTER TCSEL offset 08H MOD DC IM1 IM0 TC3 TC2 TC1 TC0 Time Code Select Byte offset 07H TC3 TC2 TC1 and TC0 designate the time code to be decoded 0000 Auto detect IRIG B IRIG A NASA 36 and 2137 modulated DC level shift time codes 0001 IRIG A 0010 IRIG B 0011 2137 0100 Battery Backed Real Time Clock IC 0101 bc630AT Master 0110 NASA 36 1010 Exte...

Page 15: ...TC0 is found at which time the bc630AT s clock is re synchronized to the time code Note Initialization takes approximately 3 seconds when Initialization Modes 1 2 and 3 are selected MOD DC Designates the time code type specified by TC3 TC0 as either Modulated or DC Level Shift 0 DC Level Shift Time Code 1 Modulated Time Code Note In auto detect mode the MOD DC bit must be 0 When non time codes are...

Page 16: ...ds with an external 1PPS or 1 5 10 MHz frequency reference if present FILTER Enables Digital Filtering of the time source signals 0 Disable filter 1 Enable filter Enabling the Digital Filter invokes an algorithm which allows the bc630AT to decode all available time sources with maximum accuracy and increases the accuracy of the flywheel during drop outs of the time source The filter should be disa...

Page 17: ...rolled by these registers which combine to produce a 16 bit unsigned value The heartbeat pulse rate represents the number of pulses interrupts generated each second The frequency range of the heartbeat rate is 1 to 2000 Hz The rising edge of the heartbeats pulses are synchronized to on time For example a heartbeat rate of 1000 would result in a generated pulse interrupt each millisecond whose risi...

Page 18: ...quests specific data from the bc630AT by writing a coded request to the Command Register at offset 0EH The baseboard must then wait for the command byte to be modified by the bc630AT firmware to indicate that the requested data is available at offset locations 00H through 06H The data format is predefined in this section Note Polling rates of the Command Register must not exceed 500 kHz Table 3 2 ...

Page 19: ...8 C20 C00 binary 0 5 microsecond count DH1 DH0 days hundreds value 0 1 2 3 bit undefined Request Event Time Last event time logged on programmed edge positive or negative or both 81H 01H 0 seconds tens seconds units 1 minutes tens minutes units 2 hours tens hours units 3 days tens days units 4 DH1 DH0 C20 C19 C18 C17 C16 5 C07 C06 C05 C04 C03 C02 C01 C00 6 C15 C14 C13 C12 C11 C10 C09 C08 C20 C00 b...

Page 20: ... 04H 0 seconds tens seconds units 1 minutes tens minutes units 2 hours tens hours units 3 days tens days units 4 months tens months units 5 year tens year units 6 0000 day of week Sunday 0 Saturday 6 Request RTC IC Time Current time of day obtained from the battery backed Real Time Clock IC as the time when 85H was written to offset 0EH 85H 05H 0 seconds tens seconds units 1 minutes tens minutes u...

Page 21: ... 1PPS or frequency reference It can also load time in other modes e g time code mode when the bc630AT is flywheeling The time loaded will not be used until the one second epoch following the load The bc630AT increments the time before loading it to the output buffer registers The time is incremented at approximately 850 milliseconds into the current frame The buffer registers are transferred to a ...

Page 22: ...e registers are used to achieve the desired functions 3 4 1 CONTROLLING THE OPERATING MODE OF THE bc630AT To control the operating mode of the bc630AT first write the appropriate data to the Control Registers Then to cause the bc630AT to take action on the Control Register data issue the Initialize command by writing 90H to the Command Register offset 0EH This action will cause the bc630AT to init...

Page 23: ... the value 40H to the Interrupt register See section 3 1 4 The Event Time is transferred to the Data Transfer Address Space by issuing the Request Event Time command 81H Following the Event Time transfer the bc630AT will write the ready flag value of 01H to the Command Register indicating the requested time is ready to be read by the XT AT bus and the bc630AT is ready to receive another command At...

Page 24: ...d is valid for heartbeat synchronization only when the Initialization mode is set to normal in the Time Code Select register see section 3 1 3 When other Initialization modes are selected the initial heartbeat period will be calculated based on the time code period specified by the mode The Synchronize Heartbeats command allows on the fly heartbeat programming without disruption of the bc630AT s c...

Page 25: ...accurate subsecond time The subsecond count is an unsigned 20 bit binary number and the Time Code Period is an unsigned 16 bit binary number The subsecond count multiplied by 0 5 sec will provide the nominal subsecond time Therefore the subsecond count varies nominally between 0 and 2E6 1 1 999 999 each second However due to the difference between the bc630AT s crystal clock frequency and the freq...

Page 26: ...IC The bc630AT has an independent battery backed Real Time Clock RTC IC which maintains time during power down of the XT AT computer The RTC IC time can be set and requested with the Set RTC IC Time Request RTC IC Time and Synchronize RTC IC commands The RTC IC maintains time with month day year hour minutes seconds and day of week format As an option in the Time Code Format Select register the RT...

Page 27: ...onization This allows the bc630AT to do the proper conversion of the Julian Time Code Format to the month day year format of the RTC IC with automatic leap year adjustment The bc630AT automatically detects an invalid Julian date i e number of days 0 or greater than 365 366 in a leap year If an invalid number of days is detected the bc630AT synchronizes only the hour min second time in the RTC IC T...

Page 28: ...his allows computer synchronization of two or more PC s without external time code Synchronization accuracy s of 1 microsecond with filter enabled can be achieved between the Master and Slaves The Master Slave mode of operation is summarized as follows A Master bc630AT decodes the time source selected in it s Time Code Select register A 1PPS synchronization pulse and serial 9600 Baud major time me...

Page 29: ... RS 422 lines If more than one bc630AT is operating as a Master the time signals are corrupted There is no hardware damage when this occurs but network synchronization is not possible When a bc630AT is designated as a slave refer to step 2 all RS 422 ports are placed in receive mode Figure 3 1 Serial Daisy Chain of Master Slave bc630AT s Figure 3 2 Bc630AT Master Slave Serial Distribution Bus with...

Page 30: ...ors 6 conductor phone cable with RJ11 male connector bc630AT RJ11 Port Female mating connector Termination Choice of one of the following methods Denotes direct 100 ohm termination on RS 422 line Denotes termination by on board 100 ohm resistors Necessary if RS 422 line is not directly terminated Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 31: ...re 4 2 shows the orientation of the J2 pinouts This output is used for linking bc630AT s used in a Master Slave configuration Regular telephone wire is used connecting the Slave bc630AT s in parallel to the master This output port can also be used for diagnostic purposes The bc630AT broadcasts time measured code period code detection status code search status software version and date code AGC sli...

Page 32: ...ing for time code with Time Code Select register set for Autodetect checking time code type Modulated time code irigb iriga nasa36 2137 lev cannot find time code type checking time code type Non modulated time codes irigb dcls iriga dcls nasa36 dcls cannot find time code type Searching for time code with the Time Code Select register set for for a specific time source time code type iriga irigb na...

Page 33: ...age data is broadcast once each second about 1 2 second after the 1PPS signal The time being broadcast following the buf2 label is valid at the rising edge of the preceding 1PPS pulse 4 3 J3 BNC CONNECTOR INPUT OUTPUT The BNC connector J3 can be chosen to input or output 1 of 10 signals from the DS 15 connector J1 The signal desired is selected with jumper JP2 Table 4 6 lists the jumper field opti...

Page 34: ...d at the rising edge of PDC ENABLE The D4 D7 data lines are valid anytime PDC ENABLE is low EACH CYCLE is a TTL representation of the time code carrier high during positive half cycles low during negative half cycles 1PPS is a TTL signal whose rising edge occurs once per second on time Figure 4 1 bc630AT Real Time Clock Module Connector Layout Artisan Technology Group Quality Instrumentation Guara...

Page 35: ...3 Future Implementation 4 Future Implementation 5 Event Trigger Input 6 1PPS Output 7 Ground 8 DC Level Shift Input 9 Isolated Return 10 External 1 5 10 MHz Input 11 Auxiliary 1 Input 12 Ground 13 Auxiliary 2 Input 14 Heartbeat Pulse Output 15 External 1PPS Input Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 36: ...Ground 3 DATA TX RX 4 DATA TX RX 5 Ground 6 1PPS TX RX Note The above pinouts apply to the bc630AT version C hardware The pinouts differ from the version A and B boards Figure 4 2 J2 Phone Jack Pinout Orientation 1 3 5 2 4 6 bc630AT Front View Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 37: ...DC Connector Pinouts J6 Signal Description 1 Ground 2 PDC ENABLE 3 D0 4 D1 5 D2 6 D3 7 D4 8 D5 9 D6 10 D7 11 EACH CYCLE HEARTBEAT 12 Not Used 13 1PPS 14 17 Not Used 18 Ground 19 5 VDC 20 5 VDC Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 38: ...nds Tens 1 0 0 0 Seconds Units Table 4 5 JP1 Jumper Positions for Isolated Time Code JP1 Position Time Code Input Jumper For J1 1 to 2 Non isolated Time Code Input 3 to 4 Isolated Time Code Input Opt 5 to 6 Non isolated Time Code Input 7 to 8 Isolated Time Code Input Opt 9 to 10 Grounded Return J1 11 to 12 Isolated Time Code Return Opt Factory Setting Total of 3 Jumpers Artisan Technology Group Qu...

Page 39: ... 11 to 12 1PPS Output 13 to 14 External 1PPS Input 15 to 16 DC Level Shift Time Code 17 to 18 External 1 5 10 MHz Input 19 to 20 Time Code Input Modulated Factory Setting Table 4 7 JP3 Jumper Positions for Master Slave Termination JP3 Position Master Slave Termination 1 to 2 No Termination 3 to 4 100 ohm Termination 5 to 6 No Termination 7 to 8 100 ohm Termination Factory Setting Artisan Technolog...

Page 40: ...e Code Return Opt Factory Setting Table 4 9 JP5 Jumper Positions for XT AT Bus Interrupt Selection JP5 Position XT AT Interrupt 1 to2 IRQ2 XT IRQ9 AT 3 to 4 IRQ3 5 to 6 IRQ4 7 to 8 IRQ5 9 to10 IRQ6 11 to 12 IRQ7 13 to 14 IRQ10 15 to 16 IRQ11 17 to 18 IRQ12 19 to 20 IRQ14 21 to 22 IRQ15 Factory Setting Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 41: ...lock Module 4 11 Table 4 10 JP6 Jumper Positions for J6 PDC Pin 13 JP6 POSITION J6 PDC PIN 13 JUMPER 1 to 2 Heartbeat Pulse 3 to 4 Each Cycle Clock Factory Setting Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 42: ...T utilizes Datum Inc s reduced chip set decoder circuitry Details on the operation of this circuitry are not available at this time 5 2 XT AT bus INTERFACE The XT AT bus interface consists of the usual assortment of bus transceivers buffers and decoders commonly found on any microprocessor based system The bc630AT uses an 8 bit dual port RAM for the I O interface Artisan Technology Group Quality I...

Page 43: ...ble external flywheel synchronization and select no interrupt sources The example manually sets up the bc630AT to the default conditions Set up control registers outportb BASE TCSEL 0 Select automatic time code selection Initialization mode normal outportb BASE MASKS 0 Disable event capture disable filter external flywheel disabled disable heartbeats no interrupts outportb BASE HBDIV0 0xE8 Set hea...

Page 44: ... polling rate to 500 KHz while inportb BASE COMMAND 3 Wait for ready flag of 3 Polling rate not to exceed 500 kHz tc_period inportb BASE 1 0x100 Get MSB of time code period and shift tc_period inportb BASE 0 Get LSB of time code and sum freq_error tc_period 33920 Figure frequency error outportb BASE COMMAND 0x80 Request time do time_delay Function slows polling rate to 500 KHz while inportb BASE C...

Page 45: ...E6 Compute real secs with offset Sub second time now in sub_seconds 6 3 SETTING THE REAL TIME CLOCK CHIP The following example shows how to set the time of the independent battery backed Real Time Clock Chip Set time in RTC chip to 01 22 91 Tuesday 13 23 45 outportb BASE 0 0x45 Load seconds data into Data Transfer Address Space outportb BASE 1 0x23 Load minutes data into Data Transfer Address Spac...

Page 46: ...chronize the Battery Backed RTC IC time to the external time code Before synchronizing be sure RTC IC is loaded with the valid year The example assumes the year is accurately set in the RTC chip outportb BASE COMMAND 0x93 Initialize bc630AT do time_delay Function slows polling rate to 500 KHz while inportb BASE COMMAND 0x13 Wait for ready value of 0x13 from bc630AT indicating synchronization proce...

Page 47: ...set location 08H or in demonstration program 630DEMO2 select IRIG B ONLY for the time code select register This step forces the bc630AT to search for a 1000Hz carrier frequency only Input the IRIG B time code through the BNC connector J3 or pin 1 of J1 Use pin 16 of U2 as the input to channel A of a dual channel oscilloscope Use the reference carrier selected in Step 2 above as the input to channe...

Page 48: ...630AT Manual 8 1 CHAPTER EIGHT DRAWING SET 8 0 GENERAL This chapter contains the schematic diagram assembly drawing and parts list for the bc630AT Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 49: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 50: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 51: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 52: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 53: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 54: ...quipment Have surplus equipment taking up shelf space We ll give it a new home Learn more Visit us at artisantg com for more info on price quotes drivers technical specifications manuals and documentation Artisan Scientific Corporation dba Artisan Technology Group is not an affiliate representative or authorized distributor for any manufacturer listed herein We re here to make your life easier How...

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