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Operation

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2019 Microchip Technology Inc.

DS50002938A-page 27

3.4.6

PPS Quantization Error Correction

For use with certain GNSS receivers, the

PpsQErr

parameter may be used to correct

known dynamic quantization errors due to the receiver itself. This is a picosecond
adjustment to the next MAC 1PPS phase measurement to account for the error.

3.5

DEVICE INFORMATION AND STATUS

Consult

“Parameters”

for a comprehensive list of all available device

telemetry parameters. They provide insight into device settings, discipline/atomic lock
status, time of day, and alarm conditions.
Several commands provide insight into hardware/software revision, device identifica-
tion, environmental extremes, and estimated NVRAM health:

• app?
• device?
• platform?
• describe?
• swrev?
• hwrev?
• serial?
• extremes?
• health?

See

“Commands”

3.6

TIME OF DAY (TOD)

The MAC maintains a TOD parameter

TimeOfDay

as a 32-bit unsigned integer, which

is incremented synchronously with the rising edge of the 1PPS output. Until set other-
wise, TOD begins counting from zero when the MAC is powered on.

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Содержание SA5 Series

Страница 1: ...2019 Microchip Technology Inc DS50002938A Miniature Atomic Clock MAC SA5X User s Guide...

Страница 2: ...may have a right to sue for relief under that Act Trademarks The Microchip name and logo the Microchip logo Adaptec AnyRate AVR AVR logo AVR Freaks BesTime BitCloud chipKIT chipKIT logo CryptoMemory...

Страница 3: ...rief description of SA5X design supported by block dia grams description of environmental issues installation guidelines and unit operation WHO SHOULD READ THIS GUIDE This document is intended for eng...

Страница 4: ...al frequency f f where f is the difference between nominal and measured value in Hz and f is the nominal frequency in Hz WARNINGS CAUTIONS RECOMMENDATIONS AND NOTES Warnings Cautions Recommendations a...

Страница 5: ...quency and Time Systems FTS Services and Support U S A Call Center including Americas Asia and Pacific Rim Frequency and Time Systems 3870 N 1st St San Jose CA 95134 Toll free in North America 1 888 3...

Страница 6: ...ive Local Sales Office Field Application Engineer FAE Technical Support Customers should contact their distributor representative or field application engineer FAE for support Local sales offices are...

Страница 7: ...1 2 Physical Description 10 1 2 1 Communications Connections 11 1 2 2 Input Connections 11 1 2 3 Output Connections 11 1 2 4 Power and Ground Connections 12 1 3 Functional Description 12 1 4 Configura...

Страница 8: ...Command Usage 38 Chapter 5 Maintenance and Troubleshooting 5 1 Preventative Maintenance 43 5 2 Electrostatic Discharge ESD Considerations 43 5 3 Troubleshooting 43 5 4 Repairing the MAC 43 5 5 Upgrad...

Страница 9: ...short term stability of a Rb reference with the long term stability of the GNSS approaching the performance of laboratory grade Cesium Beam Tube frequency stan dards see Section 3 4 1PPS Disciplining...

Страница 10: ...for example power conditioning signal buffering and so on This user guide must be used in conjunction with the current data sheet for the SA5X which is available on the Microchip web site 1 1 1 Key Fe...

Страница 11: ...as the TRS3122E or similar to attain the required LVCMOS levels Figure 1 2 shows the serial port pins 7 and 8 in the lower right region of the baseplate The default speed is 57600 bps and higher speed...

Страница 12: ...ated otherwise in Figure 1 3 If J1 connector is unused all pins should remain as No Connect Recommendation It is recommended to tie ground Pin 4 to same node as the baseplate ground Pin 2 1 3 FUNCTION...

Страница 13: ...ive to average PPS input timing is adjustable via the digital inter face with 10 ns steps using PpsOffset parameter Default PPS Pulse Width is 20 s Pulse width may be modified via the PpsWidth paramet...

Страница 14: ...the user when certain conditions are deteriorating below specified levels or when issues arise such as failure to acquire Lock or tempera ture warning These alarms are indicated by CLI status and the...

Страница 15: ...led on the test fixture it is recommended that the entire assembly be treated as ESD sensitive Retain the original MAC ESD safe packaging material in the event that the device needs to be returned to...

Страница 16: ...ntually loses lock above 75 C When practical it is recommended to monitor the baseplate temperature with a ther mocouple to ensure it remains below 75 C Alternatively one may query the telemetry param...

Страница 17: ...ove mentioned nulling capac itors are recommended to be installed on pins 1 3 5 8 EMI and Noise Considerations When a user has an application where the phase noise and spur integrity are crucial the S...

Страница 18: ...2 8V Logic_H 3 8V 0V Logic_L 0 3V Note 7 J1 Molex 1 3 PPS1 IN LVDS J1 Molex 5 7 PPS0 IN LVDS J1 Molex 8 9 15 GND J1 Molex 17 19 PPS OUT LVDS square wave 4 ns 100 J1 Molex 20 Alarm CMOS Logic_H 3V Log...

Страница 19: ...tisfied until the Lock sequence is completed after 300 seconds in this example Prior to Lock the output signal will have an inaccuracy of several ppm and drift per the MAC s internal TCXO All MAC s ha...

Страница 20: ...sition Failed If this should occur check that the environmental specifications have not been violated operating tempera ture input voltage magnetic field exposure etc and reboot the device Contact Cus...

Страница 21: ...ss the bootloader Loading After reset BSL announces it is ready waits 3 seconds bsl User requests the BSL command mode within 3 seconds BSL BSL confirms it is now in command mode baud User queries the...

Страница 22: ...108 Consult Section 3 3 1 Calibration if a larger correction is desired Note Steering commands may be entered during acquisition Locked 0 but will not take effect until lock is achieved Frequency stee...

Страница 23: ...can be adjusted by the time constant Tau which is user selectable through the TauPps0 or TauPps1 parame ter See Section 3 4 2 Selection of Disciplining Time Constant Tau for advice on choosing an appr...

Страница 24: ...oncept behind the disciplining and phase metering algorithms For more information on phase metering see Section 3 4 4 1PPS Phase Measurement Mode FIGURE 3 1 PPS State Diagram Note The user is allowed...

Страница 25: ...s etc FIGURE 3 2 Sample ADEV Curves Figure 3 2 shows the performance of several frequency references For optimum Dis ciplining performance when disciplining to a GNSS reference a time constant should...

Страница 26: ...long Disciplining time constants However the initial JamSync when disciplining is initialized cannot be avoided 3 4 4 1PPS Phase Measurement Mode Phase measurement mode does not steer or Discipline t...

Страница 27: ...all available device telemetry parameters They provide insight into device settings discipline atomic lock status time of day and alarm conditions Several commands provide insight into hardware softwa...

Страница 28: ...MAC SA5X User s Guide DS50002938A page 28 2019 Microchip Technology Inc NOTES...

Страница 29: ...as a set of parameters Error detecting With checksums garbled commands responses are more detect able Message Flow For each command message sent to the device one response message will be returned In...

Страница 30: ...sh TABLE 4 2 ESCAPE SEQUENCES Escape Sequence Resulting Character r Carriage return n New line line feed t Horizontal tab Backslash 4 1 3 Command Checksum An optional 8 bit checksum provides a measure...

Страница 31: ...esponse Always CR A carriage return character Always LF A linefeed newline character Always TABLE 4 4 ERROR RESPONSES Error Number Error Message Cause s 1 Invalid command Unrecognized command name inv...

Страница 32: ...ge CC two hex digits Currently unused feature Indicates the end of an announcement Always CR A carriage return character Always LF A linefeed newline character Always Currently announcements only occu...

Страница 33: ...nput cable delay compensa tion Default is 0 ns ns 500 000 000 Disciplining Parameters 768 Disciplining R W Disciplining to 1PPS input is enabled Default is false Boolean 0 or 1 769 PpsSource R W Selec...

Страница 34: ...lock to PPS Input 0 ns 1 to 1 000 780 DisciplineThresholdPps1 R W Phase threshold for determining a disciplining lock to PPS Input 1 ns 1 to 1 000 Oscillator Parameters 1293 AnalogTuning RO The measur...

Страница 35: ...maps to bits 10 14 as a logic high indicating a Units Value of 17 or Boolean and bit 2 as a logic high indicating that the parameter is read only 4 4 3 Alarms Parameter The Alarms parameter represent...

Страница 36: ...4 16 No External Oscillator An external oscillator was expected and not detected 5 32 Cell Heater Fault Hardware failure within the Cell Heater 6 64 Incompatible Firmware The loaded firmware is not c...

Страница 37: ...ype platform 0 Returns a short string identifying the firmware platform of the device describe 0 Returns a readable English description of the device swrev 0 Returns the software revision hwrev 0 Retu...

Страница 38: ...dated value Error 100 Invalid parameter if the parameter does not exist Error 102 Read only parameter if the parameter is read only Since V1 0 app Description Returns a short string identifying the fi...

Страница 39: ...mple response to the above command would be 38389 83629 indicating a min and max temperature of 38389 m C and 83629 m C Error 100 Invalid parameter if the parameter does not exist Since V1 0 get param...

Страница 40: ...s hardware revision typically a single character Since V1 0 latch Description Simultaneously latches the current output frequency and clears the digital tun ing This is used to center the output frequ...

Страница 41: ...rror 100 Invalid parameter if the parameter does not exist Error 102 Read only parameter if the parameter is read only Since V1 0 store Description Stores the current configuration to flash memory The...

Страница 42: ...on is the id of the parameter that updated The sec ond field is the parameter s new value So if three parameter values have changed since the previous upd command the returned string will be a list wi...

Страница 43: ...terminal interface are configured as described previously 2 Check all physical connections 3 Check that the MAC is not in compatibility mode Use the backslash character to exit compatibility mode Note...

Страница 44: ...Procedure To return equipment to Microchip for repair 1 Contact Microchip per the guidelines on page 5 to obtain a return material autho rization number RMA before returning the product for service Y...

Страница 45: ...spectrum The light travels through the temperature controlled Rb cell exposed to a magnetic C field before hitting the photodetector that detects the transmitted CPT resonance signal The photodetecto...

Страница 46: ...MAC SA5X User s Guide DS50002938A page 46 2019 Microchip Technology Inc NOTES...

Страница 47: ...u may see some minor changes in the MAC response to these commands such as string length or addi tional data fields Any serial port terminal emulator program can be used to communicate with the MAC B...

Страница 48: ...dd nnn to the current DDS Center Frequency nnn is in pp 1015 FDnnn Replace the Digital Adjust value with nnn nnn is in pp 1012 FGnnn Replace the Digital Adjust value with nnn nnn is in pp 1015 FEnnn A...

Страница 49: ...nt version NX1 The command enables Analog Tuning and persists the setting past power off FA This command has essentially the same function as the new latch command Previ ously for the legacy MAC SA3x...

Страница 50: ...1000 Functional Response digital adjustment set to 1000 10 12 Example Response One Time Frequency Adjustment 1000 FGnnn Command will replace the digital adjustment value with the specified number inte...

Страница 51: ...SB Connection This reference schematic maps a USB micro connection to the MAC s USB pins J1 2 4 6 FIGURE C 1 USB Connection RS 232 Connection This reference schematic converts USB mini signals and map...

Страница 52: ...icrochip Technology Inc FIGURE C 3 RS 232 Schematic without USB Converter 1PPS Input Connection This reference schematic converts a single ended 3 3V 50 1PPS signal to the differential LVDS format req...

Страница 53: ...c shows how the Evaluation kit maps AT voltages to the MAC FIGURE C 5 Analog Tune Schematic 1PPS Output Connection This reference schematic converts the MAC s differential 1PPS LVDS output to a sin gl...

Страница 54: ...s Guide DS50002938A page 54 2019 Microchip Technology Inc RF 10 MHz Output Connection This reference schematic buffers the MAC s RF output as a 50 3 3V signal on J2 FIGURE C 7 RF Output to Differenti...

Страница 55: ...PPS Disciplining Steering via Two Selectable SMA f Connectors 1PPS LVCMOS Output via SMA f Connector 40 C to 75 C Operating Temperature Baseplate 55 C to 100 C Storage Temperature Interface for Digita...

Страница 56: ...ists of a 3 9 x 5 1 aluminum heat sink baseplate attached to a PCBA with six mounting screws All connections are on the PCBA The physical connections of the PCBA Baseplate are highlighted in Figure D...

Страница 57: ...inates when power is provided to PS1 N A DS1 Alarm Status LED illuminates when an alarm condition is triggered J1 20 DS2 Lock Status LED illuminates when Atomic Lock is achieved 6 Evaluation Kit 2019...

Страница 58: ...e employed in order to power the other ICs on the Evaluation board D 2 5 Functional Description and Operation CAUTION To avoid electrostatic discharge ESD damage proper ESD handling procedures must be...

Страница 59: ...cted input output signal levels from the Evaluation board The levels in Appendix D take precedence over other sections of this User Guide that pertain to the MAC SA5X only D 2 5 1 TROUBLESHOOTING If a...

Страница 60: ...MAC SA5X User s Guide DS50002938A page 60 2019 Microchip Technology Inc...

Страница 61: ...stribute sublicense and or sell copies of the Software and to permit persons to whom the Software is furnished to do so subject to the following conditions The above copyright notice and this permissi...

Страница 62: ...MAC SA5X User s Guide DS50002938A page 62 2019 Microchip Technology Inc NOTES...

Страница 63: ...00 China Xian Tel 86 29 8833 7252 China Xiamen Tel 86 592 2388138 China Zhuhai Tel 86 756 3210040 ASIA PACIFIC India Bangalore Tel 91 80 3090 4444 India New Delhi Tel 91 11 4160 8631 India Pune Tel 91...

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