Pn code generators

Intro:

1. pncmem: pncode with 64k mem.
2. pnclong : long code generator 2^39-1 length.
3. pn128: pncode with 64K mem and 128K codes.

• pncmem:
• schematic ip memory code generator(.pdf)
• schematic ip memory code generator - cable
  
• pal equations (.pdf)
• Software requirements (.pdf)
• pnclong:
• schematic long code buffer board  (.pdf)
  
• pal equations (.pdf)
• Software requirements (.pdf)
  
• pn128
• pal equations (.pdf)
• Software requirements (.pdf)
  

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128 length pncode generator.

    The code has been spread over the two bits. The number of bits in each col are not the same since the codelengths are always odd and odd number are not divisible by two.
    The codeLen register and startAdr Register are now used to specify the length of B2 and B3. When the start command is received, the generator goes to the startAdr memory location and starts counting down to 0. When it reaches mem0, it resets to  the codelen memory location and then continues counting down to 0. At the end of the B2 countdown,  it goes back to startAdr memory and starts with B3 again. The X location is only accessed at the start of the B3 countdown (start of the code). The marker has been loaded into B1,B0 for this memory location.
    Any length code is allowable up to 128K (although the datataking software loads only valid pn codes). The only drawback to this device is that does not let you change the code start address. For datatking this means that the decoded echo will start with the round trip time.

Software:

• The device name is pn128. It is located on dap1 in ip slot b
• The device driver is in vw/devs/pnc/pn128Drv.c. The drive accepts the same requests as the 64Kmem board. It handles a few requests differently:
• If a start Address is sent to it, it will be ignored. When the start adress is queried it always returns 0.
• When the code length is sent by the user, it loads the codelen and start adress registers with the values needed to implement the requested code length.
• You can't use the library routine pncVwSetup() to load the memory since this routine uses the code length to determine how much memory to load. This memory load is done separately in pn128Prog.c
• The datataking program that controls it is vw/datatk/pnc/pn128Prog.c. It accepts the same keyword/values as the pncProg
• pnc_codelen 1 thru 131071  in  steps of 2^n - 1
• pnc_delay this keyword is ignored by the routine.
• pnc_baudlen .05 to 4096
• pnc_starton .. 0 Start immediate, 1 start on tick.
Notice that the keyword prefix in pnc_ and not pn128_.
• The tcl function to interface to pn128Prog.c is called pn128. It is stored in /home/online/Tcl/Proc/gen/pn128.proc . It supports the arguments:
• pn128    .. lists the current setup
• pn128  start  starts the pncode going. it ignores any starting phase
• pn128 stop    stop the generator
• pn128 "pnc_codelen 31 pnc_baud .1"  setup the generator with these keyword/values

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