ATCA Based Controller - CERN · The European XFEL X-Ray Laser Project X-Ray Free-Electron Laser...

XFELThe EuropeanX-Ray Laser Project X-Ray Free-Electron Laser

Wojciech M. Zabołotny, Krzysztof T. Poźniak, Intitute of Electronic SystemsATCA LLRF meeting, 3.12.2007

ATCA Based Controller

Wojciech ZabołotnyKrzysztof Poźniak

Institute of Electronic SystemsWarsaw University of Technology



Controller definition

TASKS:• Execution of control algorithm basing on Control Data provided by Low

Level Applications and on results of measurement of the Input signals.• Providing of processed measurement data to the Low Level Applications

layer• Monitoring and Exception Handling for safety requirements

Simple & low latency automat stabilizing the amplitude & phase

of electrical field during the single pulse

CONTROLLERLOW & HIGH

LEVEL APLICATIONTS

e x e c u t i o na r r a n g e m e n t

RF SYSTEM

C o n t r o l a l g o r i t h m s

DOOCS

managing

fieldcontrol



Requirements for the controller• Basic technical requirements

– Multiple input channels

– Low latency (as low latency as possible, however it depends on IF and technological limits)

• Modular, parametrized and reconfigurable structure– Modularity - It should be possible to distribute the design between a few AMC

boards, and even between a few ATCA carrier boards (however it will impose some additional latency)

– Parametrized – the number of memory blocks, of DSPs used, of input channels serviced may be changed without significant redesign

– Reconfigurable – the general structure of the controller will be stable, even if some blocks are moved from FPGA to DSP.

• Design methodology related requirements– Controller is supposed to be a complex system, to assure high maintainability e.g.

to avoid human errors the automatic implementation methods (DSP on FPGA, DOOCS integration) must be developed

– Full testability is needed (in simulation, with real hardware, with hardware-software cosimulation)



Reliability requirements of the XFEL controller

• Required: Continuous operation, one maintenance day per month• ATCA provided functions for increased availability:

– Redundant power supply

– Full mesh topology – no global bus for boards' interconnection, which could be blocked by a damaged board

• Controller design features contributing to increased availability– Algorithm able to operate even when some analog inputs are failed

• Use of redundancy in the analog input signals

• Possibility to work with limited number of signals

• Use of feed-forward alone as the „last resort solution”

– Possible redundant implementation of the controller

– Exception handling (e.g. Cavity gradient monitoring)



Functional requirements for the controller

• Channel calibration• Vector sum• Error calculation• Feed forward• Generation of output signals with klystron linearization• Provision of measured data for:

– Low Level Applications layer for updating of Control Data for the Controller

– For monitoring (DOOCS) and diagnostics (Exception Handling)



Multi – channel ADC

MULTI – CAVITY MODULEVectorModulator

Multi–channel Down-Converter

Control Data & Parameters

probes

Klystron

DAC

RF

SY

STE

M

Outline of the LLRF control structure

Tunercontrol

Beamdetector

C O N T R O L

DATA Preprocessing

SYSTEM MODEL IDENTIFICATIONLOW LEVEL

APLICATIONTS

Exception Detection and HandlingController Core

reflectedforward

forward

C T

R L

COMMUNICATION

IQ

Data Acquisition Memory

I/O Data

HIGH LEVEL APLICATIONTS D O O C S

MONITORING

Control Data& Parameters



Vector sum control – results from MTS testsAdaptive Feed-Forward (gain=0) Feed-Forward + Feedback (gain=100)

0 500 1000 1500

0

5

10

15

20Cavity output envelope

MV

0 500 1000 1500

-5

0

5

10

Klystron output

mA

0 500 1000 1500-0.6

-0.4

-0.2

0

0.2

0.4

time [10-6

s]

rad

Phase of cavity and klystron

0 500 1000 1500

-50

0

50

100

150

200

250

time [10-6

s]

Detuning estimation

Hz

IQAbs

cavity

klystron

IQAbs

filling

filling

flattop

flattophalfbandwidth = 220 Hz

600 800 1000 120017.99

18

18.01

18.02

18.03

Amplitud of vector sumzoomed flattop range

MV

0 200 400 600 800 1000 12000

20

40

60

80

100

Klystron forward power

KW

600 800 1000 1200-2

-1

0

1

2x 10

-3

time [10-6

s]

Phase of vector sumzoomed flattop range

rad

rms ~ 4*10-4

rad

rms ~ 2*10-4

0 200 400 600 800 1000 12000

0.2

0.4

0.6

0.8

1

time [10-6 s]

Normalized Klystron characteristics

gain []

phase [rad]



Vector sum control – with beam, without FF compensationCAVITY FIELD AMPLITUDE [MV] CAVITY FIELD PHASE [rad]



Multiboard implementation of the controller

• Single board implementation impossible:– Main problem – multiple A/D converters (96 channels needed)

– reasonable limit: 8 or 12 channels/board

• It is necessary to transmit the converted signals between the boards

• If possible, it will be preferable to split the algorithm between the boards



out

Functional Concept of Controller

LOW LEVEL APPLICATIONS

Coefficients Set-Point Gain Feed-ForwardSimulation

Error CORRECTOR FeedbackI/Q

DETECTORVectorSum

– +

CALIBRATORDACADC +

C O N T R O L L E R

Data Acquisition Memory for LLA, HLA, monitoring, diagnostics

EXCEPTION HANDLING

AMCs ATCA carrier board



Structure of the ATCA LLRF controler



ATCA communication capabilities used in the distributed controller implementation

• Low latency LVDS links provided by ATCA are essential for fast exchange of information between the distributed components of the controller

• Ethernet interface supports communication with the DOOCS system



Scalability of the XFEL controller

• The controller algorithm may be distributed between the FPGA chips, DSP processor(s) and general purpose CPU

• The number of ATCA carrier boards used to implement the controller may vary (depending mainly on the amount of inputs)

• The ATCA architecture allows us to use multiple AMC modules, multiple exchangeable AMC modules may be used– DSP modules

– FPGA modules

• Fast communication interfaces allowing data exchange between the AMC modules may be used to efficiently implement distributed algorithms

• Number of installed modules may be suited to the needs of the algorithm



Debugging of the XFEL controller in the ATCA architecture

• Debugging and continuous monitoring of integrity of procesing is essential for such distributed system

• Efficient debugging of the firmware requires fast communication links to transfer the debugging and control data

• The ATCA architecture provides the following features usable for that purpose:– Ethernet link to each carrier board

– PCI Express link to each AMC board

– JTAG connection to each AMC on the carrier

– LVDS interfaces to AMC boards (may be used for custom debugging interfaces)

• IPMI Interface („last resort solution” - low speed)



Development activity proposal

Development team● ISE Employees

● Wojciech Zabolotny, PhD● Krzysztof Pozniak, PhD● Tomasz Czarski, MSc● Maciej Linczuk, PhD

● IPJ Employees● Jaroslaw Szewinski, MSc● Grzegorz Plebański, MSc● Krzysztof Sajna, Msc

● DESY Employees/ISE PhD stud.● Waldemar Koprek, MSc● Piotr Pucyk, MSc

● DCMS PhD Students● Wojciech Jałmużna, MSc

Tasks realization● Controller

● Controller Core● Exception Detection & Handling● Control Data & Parameters● Data Acquisition Memory

● Integration with „communication” package● Simulation

● Integration with LLA simulation

Schedule (heavily depends on hardware availability) – 24 m.

● Development on the existing SIMCON hardware (due to portable design) – 12 m.

● Tests in simulation – 15 m. (in the background)

● Porting to target platform – 12 m.



Conclusions

• The proposed implementation of the Controller has been successfully verified in the FLASH experiment– however further work is needed on: exception handling, monitoring and

diagnostics, optimal distribution of algorithms (with LLA) between available resources, integration with the communication

• The Controller design is very tightly associated with the design of Low Level Applications and Communication

• Features of the ATCA technology useful for implementation of the LLRF controller– High reliability architecture

– Scalability – both on the crate level and on the carrier board level

– Low latency connections between carrier boards and between AMC boards

– Big amount of backplane connectors available for the user and full mesh connections in the ZONE2 area for easy acquisition and concentration of multiple analog signals

ATCA Based Controller - CERN · The European XFEL X-Ray Laser Project X-Ray Free-Electron Laser...

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