Fast SQ2 Feedback and TES Biasing with an Address Card

This page contains information on how to use the Address Card in a "Bias Card 2" slot to multiplex the SQ2 Feedback, and to supply a TES Bias. To use both of these features, you will need Address Card firmware revision 2.0.7 (ac_v02000007_12jun2007) or later.

Step 1: Edit your MAS "/etc/mce/mce.cfg" file

Add the following card declaration and its associated commands to your mce.cfg file, in the struct called "parameter_sets" :

{ 
name = "biasing-address commands"; parameters = 
(
{name = "bias"; id = 0xE7;},
{name = "row_order"; id = 0x01; count = 41; default_items = (0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40);},
{name = "on_bias"; id = 0x02; count = 41; min = 0; max = 16383;},
{name = "off_bias"; id = 0x03; count = 41; min = 0; max = 16383;},
{name = "enbl_mux"; id = 0x05; count = 1; min = 0; max = 2;},
{name = "const_mode"; id = 0x06; count = 41; min = 0; max = 1;},
{name = "const_val"; id = 0x07; count = 41; min = 0; max = 16383;},
{name = "const_val39"; id = 0x08; count = 1; min = 0; max = 16383;},
{name = "fb_col0";  id = 0xE3; count = 41;},
{name = "fb_col1";  id = 0xE1; count = 41;},
{name = "fb_col2";  id = 0xDF; count = 41;},
{name = "fb_col3";  id = 0xDD; count = 41;},
{name = "fb_col4";  id = 0xDB; count = 41;},
{name = "fb_col5";  id = 0xD9; count = 41;},
{name = "fb_col6";  id = 0xD7; count = 41;},
{name = "fb_col7";  id = 0xD5; count = 41;},
{name = "fb_col8";  id = 0xD3; count = 41;},
{name = "fb_col9";  id = 0xD1; count = 41;},
{name = "fb_col10"; id = 0xCF; count = 41;},
{name = "fb_col11"; id = 0xCD; count = 41;},
{name = "fb_col12"; id = 0xCB; count = 41;},
{name = "fb_col13"; id = 0xC9; count = 41;},
{name = "fb_col14"; id = 0xC7; count = 41;},
{name = "fb_col15"; id = 0xC5; count = 41;},
{name = "fb_col16"; id = 0xE2; count = 41;},
{name = "fb_col17"; id = 0xE0; count = 41;},
{name = "fb_col18"; id = 0xDE; count = 41;},
{name = "fb_col19"; id = 0xDC; count = 41;},
{name = "fb_col20"; id = 0xDA; count = 41;},
{name = "fb_col21"; id = 0xD8; count = 41;},
{name = "fb_col22"; id = 0xD6; count = 41;},
{name = "fb_col23"; id = 0xD4; count = 41;},
{name = "fb_col24"; id = 0xD2; count = 41;},
{name = "fb_col25"; id = 0xD0; count = 41;},
{name = "fb_col26"; id = 0xCE; count = 41;},
{name = "fb_col27"; id = 0xCC; count = 41;},
{name = "fb_col28"; id = 0xCA; count = 41;},
{name = "fb_col29"; id = 0xC8; count = 41;},
{name = "fb_col30"; id = 0xC6; count = 41;},
{name = "fb_col31"; id = 0xC4; count = 41;}
); 
},

Add the following card declaration to "card_types" struct:

{ 
name = "biasing-address card"; 
parameter_sets = ("open commands", "biasing-address commands");
},

Add the card to the "system->components" struct:

{ 
name = "bac"; 
nature = "physical"; 
card_type = "biasing-address card"; 
id = ( 0x08 ); error_bits = 0x00E00000;
},

Step 2: Familiarize Yourself With The Commands

http://www.phas.ubc.ca/%7Emce/mcedocs/Software/SC2_ELE_S580_515_mce_command_description.pdf

Step 3: Using the biasing address card (Address Card in Bias Card 2 slot)

After placing an AC into the BC2 slot, make the system aware of the new hardware by replacing /etc/mce/mce.cfg with the file that describes the new configuration:

cp /home/mce/mas/config/mce_v1_biasing_ac.cfg /etc/mce/mce.cfg

Following this,

mce_status -s

should no longer show entries from "bc2" and instead describe the parameters of the "bac" (biasing address card).

In experiment.cfg, set the entry "hardware_bac" to 1. If you want to do fast sq2 switching (instead of bc2 emulation), set "config_fast_sq2 = 1;" in experiment.cfg. The auto-tuning scripts check the value of "config_fast_sq2" to determine whether to execute a row-by-row sq1 servo or simply to use the preferred rows in the "sq2_rows" parameter.

Please be aware the sq2 feedback DAC range is reduced when running in this mode. With bc2, sq2 feedback is a 16 bit unsigned DAC value. With bac, sq2 feedback is a 14 bit unsigned DAC value. With bc2 in place, the sq2 feedbacks are written to "bc2 bias" or the functionally-mapped "sq2 fb", with one value for each of 32 columns. With the bac, the sq2 feedbacks are written to "bac fb_col0", "bac fb_col1", ..., "bac fb_col31"; where each of these registers accepts 41 values corresponding to the rows of the system.

TES bias lines on the bac are not available without making physical modifications to the address card.

Additional Information

• What auto-tuning routines does this require?
• How do you calculate the optimal SQ2 FB for each pixel?