Microchip / TrueTime VME-SG Timing Module

The Microchip/TrueTime VME-SG Timing Module is a 6U, single-wide VMEbus circuit card that delivers precise time synchronization and frequency generation for VME-based systems. Operating per IEEE 1014.C-1 VMEbus Specification, the module functions in three distinct modes: Generator, GPS Synchronized Generator, or Code Synchronized Generator. Time and status data transfer to the VME computer bus as five packed 16-bit BCD words with zero latency and no time-ready flags required.

– Technical Specifications

• Form Factor: 6U, single-wide VME module
• VMEbus Interface: IEEE 1014.C-1 compliant; A16/D16 slave board configuration
• Address Mapping: Memory-mapped to any 256-byte boundary in VME short address space; configurable via 8-position DIP switch
• Address Modifiers Supported: Hex 29 (short non-privileged) and hex 2D (short supervisory)
• Time Resolution: 1 µs
• Time Range: Microseconds through thousands of years
• Generator Control: Start, stop, and preset to within 1 millisecond via VME bus or external 1 PPS pulse
• Time Capture: Two independent register sets; latching on VME read request or External Event pulse
• Rate Generator: Configurable output pulses at selectable intervals (10 kHz, 1 kHz, 100 Hz, 10 Hz, 1 PPS) with interrupt generation
• Time Compare: Dual feature generating output pulses and interrupts at microsecond resolution
• Interrupt Sources: External Event, Rate Pulse, Time Compare 1, Time Compare 2

– Key Features

• GPS Synchronized Generator mode derives time and position from NAVSTAR; internal oscillator disciplined for frequency offset removal and drift minimization upon reference loss
• Code Synchronized Generator mode phase-locks to external IRIG-B time code (amplitude modulated or DC shift at RS-422 logic levels) with oscillator discipline for phase lock maintenance
• IRIG-B output: 1 kHz amplitude modulated format and RS-422 level variants
• Optional front panel display showing time, date, position, and operational status

– Typical Applications

Data acquisition systems, communication networks, and industrial automation requiring microsecond-level timing accuracy and frequency generation.

– Compatibility & Integration

Full IEEE 1014.C-1 VMEbus compliance enables integration into existing VME-based system architectures. Short address space memory mapping simplifies configuration for multi-card deployments.