Wiki source code of Trigger Howto

Version 20.1 by sndueste on 2020/01/23 12:15
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3 {{toc/}}
4
5 = Introduction (user panel)
6 =
7
8 The MTCA based triggers have a jitter in the few ps range, the delay can be shifted in 9 ns steps, One can choose between 10 Hz triggers, Triggers connected to the (fast) FEL shutters,  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]] ([[Design Paper>>url:http://ttfinfo2.desy.de/doocs/Timing/CDRv2.2short.pdf||shape="rect"]]).
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10 In short:
11
12 * the triggers are for low impedance (~~50 Ohm )
13 * signal level is + 5V - otherwise 0V (in the expert panel one can also invert the signal - base line is +5 V and trigger 0V)
14 * The trigger are send to the MTCA several ms before the first FEL pulse (3.1 ms for the "standard" trigger, 23 ms for the "early" trigger).
15 * The timer card can delay the trigger in 9 ns  steps for more than 100 ms (an option to shift the trigger in 1 ns steps is available in the expert panel)
16 * The shown delay in µs is in respect to the //first// FEL pulse. negative delay: trigger comes before FEL, positive : trigger comes after the FEL.
17 * The desired delay has to be entered in the "delay to be set" field and as second step pressing the "set delay" sends the delay value to the timer card. Then the trigger delay will be changed and the "actual delay" will be updated.
18 * The trigger can be set to only provide a trigger signal if the FEL Fast shutter is open. One has to choose which FEL shutter to use.
19 * The trigger  width can be adjusted from 9 ns to several ms in 9 ns steps
20 * The timer card can in addition to the 10 Hz triggers also provide frequencies which are linked to the FEL repetition rate and the actual burst pattern of the FEL. For details how to set these modes see below
21 * At the beamlines the triggers are provided with a  BNC patch panel
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23 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 event time)
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28 [[image:attach:image2020-1-23_12-10-59.png||width="700"]]
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39
40 = Expert panels =
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42 \\
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44 [[image:attach:image2019-9-17_13-10-56.png||height="250"]] [[image:attach:image2019-9-17_13-8-46.png||height="400"]]
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46 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)
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48 \\
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50 For each trigger channel there is in addition an **"Expert panel"** to set the properties of THIS channel
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52 [[image:attach:image2019-9-17_13-14-52.png||height="250"]] [[image:attach:image2019-9-17_13-15-38.png||width="550"]]
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54 \\
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58 = Set a constant frequency to a channel =
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60 =
61 [[image:attach:image2019-9-17_13-18-9.png||height="250"]][[image:attach:image2019-9-17_13-18-37.png||height="149"]] =
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63 \\
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65 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 !!**
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67 Since our main FEL frequency is 100.31 MHz the dividers are not straight forward:
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69 [[image:attach:image2019-9-17_14-22-29.png||width="450" align="right"]]
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71 \\
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73 (% class="wrapped" %)
74 |=(((
75 Clock frequency
76 )))|=(((
77 Divider to be set
78 )))
79 |(((
80 "1 MHz" (1000.31 kHz)
81 )))|(((
82 53
83 )))
84 |(((
85 "500 kHz" (501.5 kHz)
86 )))|(((
87 107
88 )))
89 |(((
90 "250 kHz" (250.8 kHz)
91 )))|(((
92 215
93 )))
94 |(% colspan="1" %)(((
95 "200 kHz" (200.6 kHz)
96 )))|(% colspan="1" %)(((
97 269
98 )))
99 |(% colspan="1" %)(((
100 "100 kHz" (100.3 kHz)
101 )))|(% colspan="1" %)(((
102 539
103 )))
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105 \\
106
107 == General FLASH frequencies: ==
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109 \\
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111 (% class="relative-table wrapped" style="width: 19.422%;" %)
112 |(% class="highlight-grey" title="Hintergrundfarbe : Grau" data-highlight-colour="grey" %)(((
113 (% style="color: rgb(0,0,0);" title="" %)**Name          
114 **
115 )))|(% class="highlight-grey" title="Hintergrundfarbe : Grau" data-highlight-colour="grey" %)(((
116 (% style="color: rgb(0,0,0);" title="" %)**Frequency                
117 **
118 )))|(% class="highlight-grey" title="Hintergrundfarbe : Grau" data-highlight-colour="grey" %)(((
119 (% style="color: rgb(0,0,0);" title="" %)**Divider**
120 )))
121 |(((
122 1.3 GHz
123 )))|(((
124 1300.000000 MHz
125 )))|(((
126 \\
127 )))
128 |(((
129 108 MHz
130 )))|(((
131 108.333333 MHz
132 )))|(((
133 12
134 )))
135 |(((
136 9 MHz
137 )))|(((
138 9.02777777 MHz
139 )))|(((
140 144
141 )))
142 |(((
143 4.5 MHz
144 )))|(((
145 4.513888 MHz
146 )))|(((
147 288
148 )))
149 |(((
150 1 MHz
151 )))|(((
152 1.003086 MHz
153 )))|(((
154 1296
155 )))
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157 \\
158
159 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.
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161 One has to set the delay to values less than the repetition rate ... (so for 1 MHz between 0 and 990 µs)  and the trigger width also less than the rep rate ...
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163 This results in a continuous train of pulses with the set trigger width.
164
165 = Creating an (own) burst trigger =
166
167 One can use now a SECOND trigger channel which is set to a regular 10 Hz trigger  and gate the clock output to create a burst with defined start point and length,
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169 For the example we use the FRONT.TRG2 (BL3 Trg5) as gate pulse which defines the length of the burst (set with the trigger width) and the (rough) starting point of the burst. This trigger is only used as gate and the physical trigger output is NOT used.
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171 The  second channel (here FRONT.TRG3 (BL3 Trg6) which is set to the clock frequency defines the reprate (by the FPGA clock setting) , the exact starting point of the first trigger ( by the delay ) and the width of the  MHz/kHz triggers (width).
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173 **To get from the clock to the burst trigger** one has to:
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175 * set the  "2nd source select" to the gate trigger ( here FRONT.TRG2) - this defines a second source to considder for the trigger output.
176 * and the "output source select" to "AND 2nd Ch."  this finally only sends a trigger if on both inputs (clock and gate) we have a high signal.
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180 [[image:attach:image2019-9-17_14-35-5.png||height="250"]] [[image:attach:image2019-9-17_14-34-38.png||width="400"]]
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185
186 = Real bunch trigger  - get a trigger for each FEL pulse =
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190 Sometimes it is convenient to get a trigger pulse for each pulse in the FEL. thus if the FEL number of bunches or reprate are changed, the trigger adapts accordingly.
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192 For this one has to select the source of interest in the expert overview panel (tab: "Bunch pattern") ... well for us this is FLASH1 (FL1D) or FLASH2 (FL2D)
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194 There are 6 different bunch pattern "channels" one can configure. Typically only 2 are needed ... And in each one there are 6 selectors to choose sources . We only need one - it does not matter in which one is used.
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196 [[~[~[image:attach:image2019-9-17_14-51-28.png~|~|height="250"~]~]>>attach:image2019-9-17_14-51-28.png]][[image:attach:image2019-9-17_14-47-15.png||thumbnail="true" height="199"]]
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200 In the expert panel one can now choose the configured "Bunch Pattern" as "Input source select"
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202 **NOTE: To shift the burst in time one can no longer use the delay of the individual channel BUT the delay in the "Bunch pattern" tab in the expert overview! This now shifts all bursts ... so you better know what you are doing. typically the burst is already shifted to the actual FEL timing ... Shifting the timing should be discussed with the beamline scientist / local contact ...**
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206 [[image:attach:image2019-9-17_15-4-47.png||height="250"]][[image:attach:image2019-9-17_14-52-40.png||height="250"]]
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211
212 = Different trigger events (starting points) =
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214 one can configure each channel for an individual trigger event
215
216 **FLASH1**
217
218 |(((
219 trigger No
220 )))|(((
221 function
222 )))
223 |(% colspan="1" %)(((
224 21
225 )))|(% colspan="1" %)(((
226 Trig16 + first bunch of FLASH1 - this trigger is shifted when FL1 starts later than "700"
227 )))
228 |(% colspan="1" %)(((
229 180
230 )))|(% colspan="1" %)(((
231 shifts with the start time of FLASH1 as event 21 but comes 23 ms  before the FEL
232 )))
233 |(((
234 16
235 )))|(((
236 the MCA trigger 3.11 ms before the Flash1 pulses (same as A6 but more stable)
237 )))
238 |(((
239 166
240 )))|(((
241 A6 event. still possible to use but less precise than 16
242 )))
243 |(((
244 162
245 )))|(((
246 A2 event as earliest ( 24 ms before the FEL)
247 )))
248 |(((
249 224
250 )))|(((
251 E0 event of the BL fast shutter ( 19 ms before the FEL) - to be switched off in 2020
252 )))
253 |(((
254 225
255 )))|(((
256 E1 event of the PG fast shutter ( 19 ms before the FEL) - to be switched off in 2020
257 )))
258
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262
263 **FLASH2**
264
265 |(((
266 trigger No
267 )))|(((
268 function
269 )))
270 |(((
271 22
272 )))|(((
273 Trig116 + first bunch of FLASH2 - this trigger is shifted when FL2 starts at a different start time
274 )))
275 |(((
276 181
277 )))|(((
278 shifts with the start time of FLASH2 as event 22 but comes 23 ms  before the FEL
279 )))
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281 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.
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