1 / 19

Overview of DOR Communication and Test Results for DOM Systems

This document provides a comprehensive overview of the DOR communication system utilized within DOM (Digital Optical Module) systems. It covers the OSI model, DOR block diagrams, packet presentation, and control/data bytes. Key information includes bit encoding/decoding, test results, and status updates. The discussion addresses communication protocols, data buffering, reboot problems, noise issues, and digital filtering. Additionally, next steps for optimization and debugging are outlined to enhance performance and reliability.

shaquille-charles
Télécharger la présentation

Overview of DOR Communication and Test Results for DOM Systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DOR <-> DOM Communication A Short Overview & Test Results K.-H. Sulanke DESY Zeuthen K.-H. Sulanke

  2. Contents • OSI Model • DOR Block Diagram • Packet Presentation • Control and Data Bytes • Bit Encoding / Decoding • Status • Next Steps K.-H. Sulanke

  3. OSI (Open System Interconnect) 7-Layer Model • Layer 2 by DOR firmware • Physical Layer: • 140 Ω twisted pair cable • DSUB-9 connector • … • Data Link: • UART like protocol • Half Duplex • Master / Slave • … K.-H. Sulanke

  4. Data Buffer SRAM 2 x 256Kx16 P C I - C o r e DOM 1..4 PCI Bus Altera FPGAEP20K200E DOM 5..8 Config JTAG JTAG JTAG Altera PLD EPM7064 FLASH 1M x 8 Clock 96 V Cable Interface #3 Cable Interface #2 Cable Interface #1 Cable Interface #4 DOR, Block Diagram 2 2 2 2 Reload K.-H. Sulanke

  5. FPGA +96V 10 ADC 10 Bit PREAMP -96V Cable Con. 8 DAC 8 Bit RS485 alternative use Cable Interface Scheme K.-H. Sulanke

  6. Rx / Tx Data Path, one Wire Pair PCI Bus FPGA Comm. DAC Framing, Encoding Tx_FIFO_A,B 32 8 8 Data_in Data_out Cable Con. Empty AlmEmpty ReadEna WriteEna Address Decoder 2 Wire Pair Control (8) State Machines 4 BusCycle 2 Message_rcvd InterruptControl 1 Interrupt Comm. ADC Diff. Rec. DeFrame, Decoding Rx_FIFO_A,B 10 8 Data_out Data_in AlmFull Empty WriteEna ReadEna Internal FIFOs will be replaced by external SRAM K.-H. Sulanke

  7. 31 24 23 16 15 0 User_Defined Packet_Type Packet_Length Packet Header Packet_Length: 0…65535, amount of bytes to be transferred Packet_Type: User_Defined: not relevant for hardware K.-H. Sulanke

  8. Packet Presentation Example: Sending 7 bytes to DOM_B 32 bit Tx Buffer Cable incremental number to detect lost packets Green = Control bytes added by firmware K.-H. Sulanke

  9. Byte Encoding Data Byte Control Byte Odd Parity of Adr0..1, Cmd0..3 K.-H. Sulanke

  10. Commands K.-H. Sulanke

  11. Command Sequence K.-H. Sulanke

  12. DOM Reboot Problem • After DOM power on the DOM is rebooting two times • Every reboot means a FPGA-reload as well • Problem: asynchronous loss of communication • Solution: synchronization with the data polling, DOM may only reboot after answering on DRREQ with DRBT • DOR stops all data transfer and sends COMRES until it gets an IDLE back K.-H. Sulanke

  13. Tested Functionality • Power On synchronization (COMRES command) • DOM A/B data polling (DRREQ, DRAND) • Framing and Deframing (STF, EOF) • Prevention of DOM buffer overrun (BFSTAT, MRNB, MRWB) • DOM Reboot handling (DRBT command) • Automatically detection of a missing DOM -> full bandwidth dedicated to the other one • SYSRES and TCAL not yet tested K.-H. Sulanke

  14. Data Encoding • DC-free bit encoding, 1MBit/s • “0” = quiet line, “1” = bipolar rectangular pulse, T=1µs Tx (DAC) and Rx Signal using the new Ericsson Cable (3.4 km) 1001111011…. HL_edge > 30 mV Measured between GND and one transformer tap using a Tektronix standard probe K.-H. Sulanke

  15. Start Stop 01001110 72hex Start point dU Stop point dt Digital Decoding • evaluating the HL-edge in a time window to detect a “1” • baseline correction not necessary K.-H. Sulanke

  16. Noise • problem: missing of a “standard” noise source • noise by neon lamp starters and electrical engines used to evaluate the design progress noise caused by a neon table lamp, measured at the preamp’s out K.-H. Sulanke

  17. Digital Filtering • simple digital mean value calculation over 4 ADC samples (bit time is 20 samples) mean(adc[9..0])i=(adc[9..2]i-1 + adc[9..2]i-2 + adc[9..2]i-3+ adc[9..2]i-4) lower two bits not used, 0..3 -> 0..3mV • goal is to eliminate high frequency noise spikes • the filter algorithm is limited by the available FPGA resources • Test using “natural” noise sources have shown a significant improvement • more data security by decoding the stop bit • only if the stop bit has arrived the byte is written to the Rx FIFO • prevents zero bytes, caused by single noise spike-“start bits” K.-H. Sulanke

  18. Status • long term DOS-test with 4 DOMs (2 days, 3.4km new Ericsson cable, 48KB/s/DOM) error free under lab conditions • DOM-Reboot needs still some debugging • DOM Soft Boot (command SYSRES) still has to be tested • Time calibration (command TCAL) not yet implemented K.-H. Sulanke

  19. Next Steps • DOM Soft Boot (command SYSRES) and TCAL test • Debug FIFO to record the last 256 control bytes • Possible improvements: • Adaptive edge decoder, especially for the DOM side (pk-pk value changes from 60mV to 1.2V, when a DOM is responding, but the other one is receiving) • Automatic adaption of the communication threshold after DOM power on • 8b/10b encoding scheme for better signal/noise ratio and/or higher data rates • 32 bit checksum implementation • Hardware initiated retransmit in case of an error K.-H. Sulanke

More Related