Visual Basic for Applications

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Visual Basic for Applications

• The Datapump Board
• Jamieson Olsen

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Background I

• D0 Central Track Trigger (CTT)

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Background II

• Trigger Electronics

Low Voltage Differential Signal (LVDS) Channel
Links
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Background III

• LVDS Channel Links

The PROBLEM Cant probe the LVDS pairs! Cant
use a logic analyzer or scope!
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The Datapump

• To debug our trigger hardware it would be useful
  to have a data pattern generator that would drive
  channel links.
• Likewise, it would be good to have a board that
  could capture channel link data and read it out.
• General purpose it should work with AFE, Mixer,
  and DFE boards!

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Hardware Interface

• Need some easy way to
• load test vectors into the
• transmitters and readout
• the captured data on the
• receivers.
• Whats the hardware interface?

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Hardware Interface

• OK, use a PC!
• How should the PC connect to the Datapump?
• VME is not portable
• PCI, PCMCIA, USB, IEEE1394? Huh?
• Parallel port is fast easy to program!
• (More on this later)

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Datapump Board
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Datapump Board

• Three medium-sized Field Programmable Gate Arrays
  (FPGAs) are used to build the transmitter and
  receiver circuits.
• A small CPLD acts as the parallel port interface
  bridge to the FPGAs.

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Transmitter Circuit

• Each transmitter sends 128 28-bit words (loops
  continuously).
• All ten transmitters are synchronized to the same
  counter and 53MHz clock.
• The transmitter test vectors can be read back for
  verification.

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Receiver Circuit

• Specify a unique trigger pattern for each
  receiver. Should include X (dont care) bits.
• All receivers are armed simultaneously.
• Once armed, each receiver waits for the trigger
  pattern, then captures 256 data words.

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Parallel Port

• Enhanced Parallel Port (EPP) is used
• 8-bit bi-directional datapath
• Three ports in the PC I/O space Control, Data,
  Address
• Setup the control port, then
• To write a byte outp(port, data)
• To read a byte inp(port)

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Parallel Ports and VBA

• VBA does not include the inp() and outp()
  functions.
• VBA calls functions in a DLL (ntio.dll) called
  VB_pokeIO(port, data) and VB_peekIO(port)
• The peek/poke functions in this DLL cut through
  windows and get right to the hardware ports.

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User Interface

• There are lots of test vectors which need to be
  visible simultaneously.
• An Excel spreadsheet is ideal for this
  application!
• VBA talks to the datapump via the parallel port.

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Excel Control Buttons

• Configure the datapump FPGAs.
• Write/Verify the transmitter test vectors.
• Specify the trigger pattern for each receiver.
• Arm and readback the receiver data.

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Configuration

• Must do this each time datapump is power cycled.
• Originally this was a C program and DOS batch
  file, but it was all converted into VBA.
• Writes three files to the datapump PLDs.
• The VBA module is called HEXDUMP, calls two subs
  Vbwrite_C() and hexdump().

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Datapump Transmitters
VBA module datapump, subroutines
Download_Vector() and Verify_Vector()
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Datapump Receivers
VBA module datapump, subroutines setup_U1() and
readback_U1()
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• Backup Slides

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EPP Registers
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DFE Motherboard