http://atlas.physics.lsa.umich.edu/docushare/default.htm
PROM XC17128E for Demoboard
Demoboard is a simple circuit board, which contains LVDS
receivers, transmitters, and a control circuit implemented in an
XC4005E XILINX FPGA. The FPGA accepts encoded triggers
from the serial commands in the standard TDC format and
generates output that emulates the ATLAS Muon TDC serial data
stream. The FPGA instruction setting ( bitfile ) is stored and
downloaded from a Xilinx XC17128E PROM, plugged in an 8 - pin
dip socket. By changing the PROM (manually unplug/plug) the
circuit delivers different TDC data patterns. It is important to note
that the clockin g within the Demoboard is derived from one of the
CSM - 0 clock inputs. This RJ45 connector is the one nearest the
DC input power connector. This input must be cabled to the CSM -
0. The board also has a reset button that reloads and initializes the
FPGA. When the unit is recabled to the CSM - 0 it is a good idea to
reset the board since the clock may have been interrupted.
Four PROMs are provided with the Demoboard, each labeled with
a number (1 through 4). The following list explains the pattern of
TDC words generated by each PROM:
1. PROM#1 sends out 99 data words serially, using TDC ID code
0011 for each trigger it receives from the CSM0 board. The first
trigger following a reset generates 100 words. This was not intended
but presents no difficulty since its origin is known.
2. PROM#2 continuously sends data words, beginning with the TDC
ID code 0011 as soon as it receives the first trigger from CSM0
board. The effective frequency of these words is 100 KHz/TDC
obtained by adding a pause period between consecut ive data words.
3. PROM#3 sends out 6 data words every time it receives a trigger
from CSM0 board. The data word order is the following:
• TDC header TDC ID = 1010;
• Data word whose TDC ID = 0010;
• Data word whose TDC ID = 0011;
• Data word whose TDC ID = 0100;
• Data word whose TDC ID = 1111;
• TDC trailer (TDC ID = 1100).
Useful hint: The CSM, while passing data words, checks the TDC
ID and does not accept a data word beginning with ID = “F” (the 5
th
one), and will discard it. 4. PROM#4 sends out 98 dat a words every time it receives a trigger from CSM0 board. The data word order is the following: • TDC header (TDC ID = 1010); • 2 data words beginning with TDC ID = 0011 for each of the 24 channels; • 2 data words beginning with TDC ID = 0100 for each of the 24 channels; • TDC trailer (TDC ID = 1100). The total number of words sent out is therefore 98 for each trigger. For further information just ask me through e - mail ( binchi@umich.edu
)
and I can provide you the Verilog HDL used for each of them.
Run Sequence
A MiniDaq operational sequence might look like:
• Run Project (CVI followed by open project)
• Load Profile (default is fine here)
• Diagnostics >> Do Cold Start
• Enable TDCs which are connected to the demoboard
• Begin Ru n (with either file output or not)
• End Run (note you can generate a lot of data in a short time)
• If File is generated, Run SKELUNIX.EXE filename (implied .dat)
• Examine the file, filename.txt, with your favorite editor.
• Compare your output to that expected for the demoboard PROM
set you are using.
If you are using the continuous PROM set with a tomographic CSM - 0,
you will find the counts in the histogram bins to be given by:
Count = 100,000*time between readouts/24
Thus for an external trigger rate of 20H z (50ms or 0.05s) the count in
active channels (the ones to which the demoboard is cabled) should be
5000/24 or just over 200 = d0 (hex). For 10Hz the number is doubled or
1a0. The histogram is accumulated in 16 bits so counting beyond
65,535 results in th e number wrapping back to 0.
Remember that the trigger for the tomographic CSM - 0 really means
output and zero histogram. Thus, the first trigger results in the output of
whatever has been accumulating in the histogram. If a run is stopped
and external tri ggers to the CSM - 0 are blocked by this halt condition
and the demoboard is operating in continuous mode, a large number of
counts will accumulate before a new run is started. The first histogram
after a new run start will have an uncertain number of counts . In fact it
may have rolled over the 65,535 count limit many times.