Bruker DPP1 - Functional Coordination between the Hardware and Software

Description
Technical Manual Version 001 BRUKER BIOSPIN 45 (55)
Note: „Directly before it“ means after the previous gradient packet belonging to the
NEXT Gradient. „Directly after it“ means up to the end of the following „Next Val
-
ue“ phase.
• The Next Gradient is stored right before the next „Next Value“ flank as „NG
flag“. The „NG flag“ is then deleted by the Next Value and stored as „GF“ and
„GFD“ until the next „Next Value“. The „GFD“ is read as a status register bit
from the DSP in the interrupt service and marked with „logically-1“, the avail
-
ability of a complete gradient packet in FIFO.
• „GF“ is always set by the „Next Value“ if a stored „NG Flag“ exists. This means
with a Next Value phase the GF and GFD remain constant on „1“.
GF:=NF-Flag;
GFD:=GF;
• Each „Next Value“ sets the INT interrupt signal to the DSP and the CALC bit,
which mark the computing phase of the DSP.
• In the interrupt service the DSP reads the status of the GFD, puts the INT bit
back as promptly as possible, reads possible gradient words from the input
FIFO to the control word, counts and transfers the calculated gradients words
and the control word in the output FIFO. As a last action before leaving the ser
-
vice routine, the CALC bit is deleted.
• When the CALC is set the „Next Value“ increments an error counter.
• The control word is the last word of a gradient packet in both FIFO‘s. With the
DPP1 the control word is transferred with the packet and is used to control the
gradient amplifier.
With the DPP (48-bit test version) the control word from the out FIFO serves
only as a delimiter for the packets and is not transferred with the packet to the
gradient amplifier. The reason for this is that the control word in the BGU leads
to the deletion of the register.
Functional Coordination between the Hardware and Software
Conditions and software relevant changes when using the DPP:
• In contrast to the case where a DPP is not used, the Next Gradient doesn‘t
switch the gradients, rather determines the Next Value flank, which switches
the gradients. In addition the Next Gradient must appear within a certain Next
Value phase. The associated gradient packet will then be effective in the fourth
phase thereafter!
• The duration between the Next Gradient NG
i
and NG
i+1
affects (rounded on
whole Next Value phases) the gradients g
i
, when g
i
is the packet that is acti-
vated with NG
i
.
• During a Next Value phase only a Next Gradient is given.
• The Next Gradient belonging to the gradient packet must be transferred to the
end of the following Next Value phase and must be available at the output of
the in_FIFO.
• It is possible that, for example, all gradient packets are loaded first, to the ex-
tent that in_FIFO can accommodate them. During the experiment the Next
Gradients would then only be transferred.
• The transfer sequence of the gradient packets must correspond to the switch-
ing sequence specified by the Next Gradient.