Wiki source code of Trigger Howto

Version 9.1 by sndueste on 2019/09/17 14:22
Show last authors
1
2
3 {{toc/}}
4
5 = Introduction =
6
7 The MTCA based triggers have a jitter in the few ps range, the delay can be shifted in 1 ns steps (over many ms), one can choose between 10 Hz triggers, frequencies locked to the pulses (e.g. 1MHz) and the actual bunch patterns. A detailed description can be found in [[x2Timer manual>>attach:x2Timer.pdf]].
8
9 in short: the triggers are for low impedance (~~50 OHM terminated ?? ), 5V triggers with an adjustable width. The main control panel for the x2 timer has the control options for the 3 front modules (connected with a RJ45 cable - connecting to a "trigger box" with 2 trigger exits (Lemo) each) and 8 Lemo exits at the back of the crate. in the BL-beamline case these triggers are connected to the BNC (patch panel) ports at the rack.
10
11 The main control can be done with a simplified user panel which can handle the timing in respect to the FEL pulses and not in respect to some (arbitrary) reference time ( Event)[[~[~[image:url:http://hasfweb.desy.de/pub/Setup/TriggerHowto/Trigger_scheme.gif~|~|alt="Trigger_scheme.gif" width="800"~]~]>>attach:Trigger_scheme.gif]]
12
13
14 \\
15
16 = different trigger events (starting points) =
17
18 one can configure each channel for an individual trigger event
19
20 **FLASH1**
21
22 (% class="wrapped" %)
23 |(((
24 trigger No
25 )))|(((
26 function
27 )))
28 |(((
29 16
30 )))|(((
31 the MCA trigger 3.11 ms before the Flash1 pulses (same as A6 but more stable)
32 )))
33 |(((
34 166
35 )))|(((
36 A6 event. still possible to use but less precise than 16
37 )))
38 |(((
39 162
40 )))|(((
41 A2 event as earliest ( 24 ms before the FEL)
42 )))
43 |(((
44 224
45 )))|(((
46 E0 event of the BL fast shutter ( 19 ms before the FEL)
47 )))
48 |(((
49 225
50 )))|(((
51 E1 event of the PG fast shutter ( 19 ms before the FEL)
52 )))
53 |(((
54 21
55 )))|(((
56 Trig16 + first bunch of FLASH1 - this trigger is shifted when FL1 starts later than "700"
57 )))
58
59 \\
60
61 \\
62
63 **FLASH2**
64
65 (% class="wrapped" %)
66 |(((
67 trigger No
68 )))|(((
69 function
70 )))
71 |(((
72 22
73 )))|(((
74 Trig116 + first bunch of FLASH2 - this trigger is shifted when FL2 starts at a different start time
75 )))
76 |(((
77 181
78 )))|(((
79 shifts with the start time of FLASH2 as event 22 but comes 22 ms ! before the FEL
80 )))
81
82 from this trigger as starting point one can shift the timing in 9 ns steps first and finally in 0.9 ns steps for fine adjustment.
83
84 \\
85
86 = Expert panels =
87
88 \\
89
90 [[image:attach:image2019-9-17_13-10-56.png||height="250"]] [[image:attach:image2019-9-17_13-8-46.png||height="400"]]
91
92 With the **"Expert overview"** one gets the overview over all channels available on the timing card and can configure the card. This is useful to look what channels are using clock settings or burst mode settings that one wants to change ... and using the other tabs one can set parameters for clocks and bursts (see below)
93
94 \\
95
96 For each trigger channel there is in addition an **"Expert panel"** to set the properties of THIS channel
97
98 [[image:attach:image2019-9-17_13-14-52.png||height="250"]] [[image:attach:image2019-9-17_13-15-38.png||width="550"]]
99
100 \\
101
102 \\
103
104 \\
105
106 = Set a constant frequency to a channel
107 [[image:attach:image2019-9-17_13-18-9.png||height="250"]][[image:attach:image2019-9-17_13-18-37.png||height="149"]] =
108
109 \\
110
111 \\
112
113 The timer card provides the option to generate  frequencies that are synched to the FEL reprate on the ps level. One can set 3 Clocks by deviding the reference frequency of 54.2 MHz by n.** Please check (using the Expert overview ) before changing a frequency of it is used for some other channel !!**
114
115 Since our main FEL frequency is 100.31 MHz the dividers are not straight forward:
116
117 (% class="wrapped" %)
118 |=(((
119 Clock frequency
120 )))|=(((
121 Divider to be set
122 )))
123 |(((
124 "1 MHz" (1000.31 kHz)
125 )))|(((
126 53
127 )))
128 |(((
129 "500 kHz" (501.5 kHz)
130 )))|(((
131 107
132 )))
133 |(((
134 "250 kHz" (250.8 kHz)
135 )))|(((
136 215
137 )))
138 |(% colspan="1" %)(((
139 "200 kHz" (200.6 kHz)
140 )))|(% colspan="1" %)(((
141 269
142 )))
143 |(% colspan="1" %)(((
144 "100 kHz" (100.3 kHz)
145 )))|(% colspan="1" %)(((
146 539
147 )))
148
149 Once a clock is configured with the right frequency one can choose in the "expert panel" of the according channel the "FPGA clock" in the "input source select"  chooser.
150
151 One has to set the
152
153 [[image:attach:image2019-9-17_14-22-29.png||width="450"]]
154
155 \\
156
157 This results in a continuous train of pulses with the set trigger width
158
159 \\
160
161 \\
162
163 * in order to generate a stable frequency one has to set the input source to FPGA clock (and use dividers to get the desired frequency)
164 * to generate the burst patterns of the FEL one has to choose a trigger event (best 116 for FLASH 2 and 16 for FLASH1) and activate Destination 1 for FLASH1 and Destination 2 for FLASH2 . finally one has to assign the activated Bunch pattern mask to the trigger channel of choice . now the pattern can be shifted and the trigger width can be changed as with the 10 Hz triggers. **IMPORTANT: to move the bunchtrain to the desired starting point the DELAY in the expert panel (see below) has to be used. The Trigger in the user panel (see above) has to be set to 0 !!!**
165 [[~[~[image:url:http://hasfweb.desy.de/pub/Setup/TriggerHowto/mtcatrigger2k.png~|~|alt="mtcatrigger2k.png" width="607" height="458"~]~]>>attach:mtcatrigger2k.png]]
166
167 here an example defining the bunch pattern for FLASH1 to mask 1
168
169 \\
170
171 [[here is a link to the old VME trigger system>>doc:FLASH.VMETrigger]]
172
173 \\
174
175 \\