The Microchip/Bancomm bc635VME is a VMEbus Time and Frequency Processor that delivers precise time and frequency synchronization for VMEbus-based systems. It integrates a disciplined 10 MHz oscillator with 100-nanosecond clock resolution to acquire time from IRIG B, IRIG H, 2137, or XR3 time code signals. The module generates synchronized clock outputs at 1, 5, or 10 MHz (TTL), performs time code generation and translation, and captures event times on external TTL pulse triggers with coincident bus interrupt generation. Flywheel operation maintains time accuracy at the last known reference rate during synchronization loss. A battery-backed real-time clock sustains +/-10 PPM accuracy during power interruption, while front-panel LEDs display time in hours, minutes, and seconds.
Technical Specifications
Time Acquisition
• Primary sources: IRIG B, IRIG H, 2137, XR3 time codes
• Disciplined 10 MHz oscillator rate-matched to input reference
• Synchronization loss handling via flywheel operation
Clock and Frequency Outputs
• Programmable output: 1 MHz, 5 MHz, or 10 MHz TTL
• Precision 10 MHz frequency output
• Programmable periodic output: 10,000,000 / (n1 × n2) Hz, where 1 < n1 < 65536 and 1 < n2 < 65536
• Internal clock resolution: 100 nanoseconds
Time Code Generation
• IRIG B (modulated and DC level shift formats)
• IRIG H (DC level shift format)
Event Capture and Interrupts
• Event time capture on external TTL pulse (positive or negative edge)
• Bus interrupt generation coincident with external TTL events
• Programmable time strobe output (days through milliseconds; "each second" mode with millisecond resolution)
Power and Timekeeping
• Battery-backed real-time clock: +/-10 PPM accuracy during power loss
VMEbus Integration
• A16:D16 data transfers
• Register block: any 64-byte boundary
• VXIbus compatibility: selectable via DIP switch
– Key Features
• Zero-latency high-speed time requests
• Programmable interrupt sources and IRQ levels
• Front-panel LED time display (HH:MM:SS format)
– Typical Applications
Network synchronization, precision event timestamping, frequency distribution in VMEbus instrument clusters, time-critical industrial control systems.
– Compatibility & Integration
Direct VMEbus integration with standard A16:D16 addressing. VXIbus operation available through DIP switch configuration.
