MLU Programming
The CAEN 1495 is programmed as an MLU to form triggers.
Contents
Picture of MLU
http://userweb.jlab.org/~rom/mlu.xfig.png
GUI used for control
Picture
http://userweb.jlab.org/~rom/mlugui.png
Instructions: Login to "atrig" and type "trigsetup". The GUI is obvious but if you need help press "HELP" on it for more info.
How to select the MLU programming (trigsetup)
(but you can also use the GUI on "atrig" -- see above)
To setup the MLU, use the code "trigsetup" on the atrig account on adaq1 or another 64-bit computer in Hall A.
Type "trigsetup" and a fairly obvious GUI pops up. The GUI has a HELP button with more information. These instructions supplant the "primitive way" listed below; however, that way still is available.
How to select the MLU programming (primitive way)
The L-HRS and R-HRS have MLUs deployed. The MLUs are controlled by the VME-based PCs: on L-HRS it is intelha3 and on the R-HRS it is halladaq8. All the following instructions work for both MLUs.
To setup the MLU, login to intelha3 (unfortunately, you can only login as root as the moment) and type "setmlu" and answer the obvious question.
New as of April 15, 2014: the outputs can be disabled. This is fairly obvious if you type "setmlu" or if you look in /root/mlu/modefile. (A "1" bit enables the output and a "0" disables.)
When that PC reboots it puts the MLU into the state defined in /root/mlu/modefile. This file is modified by setmlu, and the code that writes to the mlu is invoked. That code is /mlu/initmlu. This code is also called every 4 minutes under cron, just to ensure that the MLU is always in the right state (does no harm). Finally, the code is called when the PC reboots, using an entry in /etc/rc.local
Programming Details
MLU programming.
Feb 5 2014 R. Michaels
Note, channel #1 is at the bottom.
There are 3 inputs
A and B - 32 chan ECL -- to be ignored
E - 8 chan NIM -- to be used
There are 3 outputs
C - 32 chan LVDS (converted to ECL with another board)
F - 8 chan NIM
A ||
||
B || * E NIM input
|| *
LVDS output C || * F NIM output
|| *
The outputs are arranged so that (with indices starting at 1):
C(1-8), C(9-16), C(17-23), C(24-32), and F(1-8)
are identical.
This provides 5 copies of the trigger signals.
Inputs on E
1. S0 scintillator
2. S2 scintillator
3. GC gas cherenkov
4. SH shower
5. EDTM
6. Clock
GMp Standard Triggers
Outputs
1. S0 & S2 (logical "and")
2. S0 & GC
3. S2 & GC
4. S0 & SH
5. S2 & SH
6. GC & SH
7. EDTM
8. Clock
Single Detector Triggers and other triggers
Single Detector Triggers -- Alternative MLU -- software selectable.
(normally not used, but might be used by DVCS)
Outputs
1. S0
2. S2
3. GC
4. SH
5. S0 || S2
6. (S0 & S2) || (S0 & GC) || (S2 & GC) 2/3 trigger
7. EDTM
8. Clock
Notes from Testing
Here are some notes from testing the setup in the TEDF building.
Notes from testing
All the NIM outputs have appropriate polarity.
One must take care to select the jumpers so that NIM inputs
have 50 ohm termination -- otherwise you get reflections.
There were a couple channels that didn't have 50 ohm even
with the jumpers set right; Bill Gunning fixed it.
The ECL outputs 7 and 8 are flipped polarity.
This could affect some timing.
For the LVDS to ECL converter I have, 4 channels were bad
(index starting at 1): 7, 9, 23, and 32.
We'll also need to ask for more converters.
Input pin #8 on the NIM mezzanine E is broken on L-HRS MLU.
We don't use it, though. We should get spare cards.
The delay through the 1495 to NIM output is 20 nsec.
The logic follows the timing of the inputs. Jitter
is negligible.
If the power is turned off
-- the FPGA programming is preserved
-- but the module must be initialized with
software, or there is no output.
We have arranged to initialize the MLU with software
whenever the VME board is rebooted.
