Difference between revisions of "Row-specific SQ2 feedback (fast switching)"

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The SQ2-Feedback (SQ2FB) output of the MCE, controlled by a DAC can be set to either a constant value or a row-specific set of values switching at row-visit rate. The SQ2FB output is driven by the card plugged into the BC2 slot of the MCE. Either a Bias Card or an Address Card can be plugged into the BC2 slot.
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The SQ2-Feedback (SQ2FB) output of the MCE, controlled by a DAC can be set to either a constant value or a row-specific set of values switching at row-visit rate. The SQ2FB output is driven by the card plugged into the BC2 slot of the MCE.
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= Bias-card-driven SQ2FB =
 
  
 
== Hardware requirements ==
 
== Hardware requirements ==
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;Relevant mce parameters
 
;Relevant mce parameters
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:'''enbl_mux''' : enable /disable multiplexing DAC values. Default: mode = 0 (disabled).  
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* '''{{param|bc|enbl_mux}}''' : one value per channel, to enable / disable multiplexing DAC values. Default: mode = 0 (disabled); write 1 to enable.
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::When multiplexing is disabled, DACs are loaded with values specified using flux_fb parameter,
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**When enbl_mux = 0, DACs are loaded with values specified using flux_fb parameter.
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::When multiplexing is disabled, DACs are loaded with fb_col values.
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**When enbl_mux = 1, multiplexing is enabled and DACs are loaded with a new value from fb_col# at each row switch.
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:'''flux_fb''' : flux-feedback values for all 32 16-bit DACs on Bias Card.
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*'''{{param|bc|flux_fb}}''': values for each of the 32 flux-feedback 16-bit DACs on Bias Card.  These are used for any column having enbl_mux = 0.
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:'''fb_col0, fb_col1, ... to fb_col31''': upto 41 sq2fb values per column (output DAC or fb_colx), effective when enbl_mux = 1 or multiplexing mode is enabled
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*'''{{param|bc|fb_col0}}, {{param|bc|fb_col0|fb_col1}}, ... to {{param|bc|fb_col0|fb_col31}}''': registers, each of which may contain up to 41 sq2fb values.  These are only used when enbl_mux = 1 for the column
  
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:'''row_len''' : number of 50MHz clock cycles per row visit, i.e. number of clock cycles to switch between sq2fb values.
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Muxing can be enabled / disabled on each column independently. For classic, constant FB output, ensure enbl_mux = 0 0 0 0 ... .
  
 
== Software requirements ==
 
== Software requirements ==
  
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* mas/trunk : r503 or later - servo programs will automatically detect the fast bias card.
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* mas/trunk : r510 or later - servo programs will automatically detect the fast bias card.
 
* mce_script/trunk: r764 or later
 
* mce_script/trunk: r764 or later
  
 
;Configuration instructions
 
;Configuration instructions
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* When creating mce.cfg:
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* When creating [[mce.cfg|mce.cin]]:
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** $hw_rev["bc"] = "revF" or greater.
 
 
** $fw_rev["bc"] = 0x5000005 or greater.
 
** $fw_rev["bc"] = 0x5000005 or greater.
 
** $card_list should indicate a "bc2" (i.e. not a "bac")
 
** $card_list should indicate a "bc2" (i.e. not a "bac")
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*** config_fast_sq2 = 0;    # disable fast-SQ2 switching
 
*** config_fast_sq2 = 0;    # disable fast-SQ2 switching
 
** Set
 
** Set
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*** hardware_bac = 0;       # bc2 is not a bac, it's a bc2.
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*** hardware_fast_sq2 = 2; # new bias card, supports fast- and no-switching
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*** ''(In older mce_script, the equivalent is to set hardware_bac = 0)''
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= Address-card-driven SQ2FB =
 
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See older instructions here: [[ Fast SQ2 Feedback and TES Biasing with an Address Card ]]
 
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== Hardware requirements ==
 
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* No modifications are necessary to the address card.
 
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* Note that the usual BC2 bias/heater line is not available when the biasing address card (BAC) is in use. However, if needed, the address-card hardware can be physically modified to provide the same functionality, for details see: http://www.phas.ubc.ca/~scuba2/sc2mce/system/addr_card/design/ECOs/AC-ECO049-20080508.doc
 
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* The SQ2 FB DAC range is reduced from 16 to 14 bits when using the BAC.
 
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== Firmware requirements ==
 
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* AC 5.0.0 or later
 
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;Relevant mce parameters
 
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:enbl_mux
 
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:const_val
 
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:fb_col0, fb_col1, ... to fb_col31
 
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:const_val39
 
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:row_len
 
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See [[ http://www.phas.ubc.ca/~mce/mcedocs/software/SC2_ELE_S580_515_mce_command_description.pdf | MCE Command Description ]] for more details.
 
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== Software requirements ==
 
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* mas/trunk : r439 or later
 
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* mce_script/trunk : this has worked for a while...
 
  
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;Configuration instructions
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[[Category:Bias Card]]
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* When creating mce.cfg:
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[[Category:Bias Card Firmware]]
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** $card_list must indicate a "bac" instead of a "bc2"
 
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** mce_status -g should show entries for "bac fb_col#" and "sq2 fb_col#" and no entries for "bc2"
 
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* In experiment.cfg:
 
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** Set one of
 
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*** config_fast_sq2 = 1;    # enable fast-SQ2 switching (and tuning)
 
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*** config_fast_sq2 = 0;    # simulate non-fast-SQ2 bc2 by writing the same FB value for each row.
 
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** Set
 
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*** hardware_bac = 1;      # we are using a bac
 

Latest revision as of 19:04, 2 August 2018

The SQ2-Feedback (SQ2FB) output of the MCE, controlled by a DAC can be set to either a constant value or a row-specific set of values switching at row-visit rate. The SQ2FB output is driven by the card plugged into the BC2 slot of the MCE.

Hardware requirements

  • Bias cards prior to Rev. F have a slow opamp at the output followed by 2 sets of kHz-range RC filters that limit the output switching frequency to few kHz range and prevents the output from switching at the row-visit rate, typically around 500kHz. Therefore, when these bias cards are used in BC2 slot, only a constant SQ2FB value (one value per array-column) can be specified.
  • Bias Cards Rev. F and later have faster outputs and they can be switched at row-visit rates up to about 900kHz .

Firmware requirements

The firmware support for switching SQ2FB values at row-visit rate is added starting revision BC 5.0.5.

Relevant mce parameters
  • enbl_mux : one value per channel, to enable / disable multiplexing DAC values. Default: mode = 0 (disabled); write 1 to enable.
    • When enbl_mux = 0, DACs are loaded with values specified using flux_fb parameter.
    • When enbl_mux = 1, multiplexing is enabled and DACs are loaded with a new value from fb_col# at each row switch.
  • flux_fb: values for each of the 32 flux-feedback 16-bit DACs on Bias Card. These are used for any column having enbl_mux = 0.
  • fb_col0, fb_col1, ... to fb_col31: registers, each of which may contain up to 41 sq2fb values. These are only used when enbl_mux = 1 for the column

Muxing can be enabled / disabled on each column independently. For classic, constant FB output, ensure enbl_mux = 0 0 0 0 ... .

Software requirements

  • mas/trunk : r510 or later - servo programs will automatically detect the fast bias card.
  • mce_script/trunk: r764 or later
Configuration instructions
  • When creating mce.cin:
    • $fw_rev["bc"] = 0x5000005 or greater.
    • $card_list should indicate a "bc2" (i.e. not a "bac")
    • mce_status -g should show entries for "bc2 fb_col#" and "sq2 fb_col#" as well as "bc2 flux_fb" and "sq2 fb".
  • In experiment.cfg:
    • Set one of
      • config_fast_sq2 = 1; # enable fast-SQ2 switching (and tuning)
      • config_fast_sq2 = 0; # disable fast-SQ2 switching
    • Set
      • hardware_fast_sq2 = 2; # new bias card, supports fast- and no-switching
      • (In older mce_script, the equivalent is to set hardware_bac = 0)
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