Download Programmer`s Manual PIXIE-4

4 User Accessible Variables
User parameters are stored in the data memory space of the on-board DSP. The organization
is that of a linear memory with 16-bit words. Subsequent memory locations are indicated by
increasing addresses. The data memory space, as seen by the host computer, starts at 0x4000.
There are two sets of user-accessible parameters. 256 words in data memory are used to store
input parameters. These can and must be set properly by the user application. A second set of
160 words is used for results furnished by the PIXIE-4 module. These should not be
overwritten.
As of this writing the start address for the input parameter block is InParAddr=0x4000 and
for the output parameter block it is OutParAddr=0x4100, i.e. the two blocks are contiguous
in memory space. We provide an ASCII file named PXIcode.var which contains in a 2column format the offset and name of every user accessible variable. We suggest that user
code use this information to create a nameÆaddress lookup table, rather than relying on the
parameters retaining their address offsets with respect to the start address.
The input parameter block is partitioned into 5 subunits. The first contains 64 data that
pertain to the PIXIE-4 as a whole. It is followed by four blocks of 48 words, which describe
the settings of the four channels.
Below we describe the module and channel parameters in turn. Where appropriate, we show
how a variable can be viewed using the PIXIE-Viewer.
4.1
Module input parameters
MODNUM: Logical number of the module. This number will be written into the header of
the list mode buffer to aid offline event reconstruction.
MODCSRA: The Module Control and Status Register A
Bit 0:
If set, timestamps are latched by local triggers, not by the (last) group trigger.
This preserves trigger timing information for runs without waveform
acquisition
Bit 1:
If set, DSP acquires 32 data buffers in each list mode run and stores the data
in external memory. If not set, only one buffer is acquired and the data is kept
in local memory. Must be set/cleared for all modules in the system. If set,
clear bit 0 of DBLBUFCSR
Bit 2:
Bits 2 and 15 control trigger distribution over the backplane. If neither bit 2 or
bit 15 are set, triggers are distributed only between channels of this module.
Otherwise, triggers are distributed as follows:
30
PIXIE-4 Programmer’s Manual V1.61
© XIA 2008. All rights reserved.