Diamond FOFB Communication Controller

iconDiamond Light Source Fast Orbit Feedback Communication Controller Specification and Design document includes detailed information on Diamond Light Source Fast Orbit Feedback (FOFB) system architecture, and Communication Controller (CC) Design specification along with FPGA implementation details.

This page contains the most recent updates to the Communication Controller design, implementation and installation. For detailed release history, please visit CC RELEASE HISTORY

Contact

contact

Latest Version: v2.02.3

1. New Features

  • N/A

2. Resolved Issues

  • A death period of 64 clock cycles are introduced for PMC time frame start bit generation to allow a window for TX/RX fifo reset.
  • RX Fifo reset logic on every timeframe is fixed. A bug in this logic was the cause of glitches appearing when a BPM starts walking away in phase.

3. Known Issues

  • N/A

Previous Version: v2.02.2

1. New Features

  • N/A

2. Resolved Issues

Following modifications are made only on PMC design. CC operation is not affected.

  • DMA handshaking start bug is fixed. It, now, happens at the rising edge of the time_frame_end signal, rather than the falling edge.
  • Missed DMA counter reading, and DMA acknowledment are synchronised. You do not need to write to dma_ack register anymore. This used to cause occasional misreadings on the missed_dma_counter.
  • fofb_node_mask register has to be read before initiating DMA transfer.
  • missed_dma_counter is fixed. It reads 0 (zero) when there is no dma miss. It returns 0 (zero) as x and y position data for inactive BPMs on the network.

3. Known Issues

  • It is recently observed during our tests on Diamond SR that glitches appear on acquired orbit data when a BPM starts losing its synchronisation. The position and value of the glitches depend on the network topology and it is very difficult to debug the problem. However, this problem does not appear when all the BPMs are synchronised.