PCIe-24DSI32
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3-22
3.11 Board Configuration Register
The read-only board configuration register (Table 3.11.1) contains the existing firmware
revision, and a status field that indicates the availability of optional features.
Table 3.11.1. Board Configuration Register
Offset: 0000 0024h
Default: 000X XXXXh
BIT FIELD
DESCRIPTION
D00-D11
Firmware Revision
D12-D15
(Reserved status flags).
D16
High if the board contains only 16 input channels.
D17
High if the board contains only 8 input channels.
D18-D31
(Reserved)
3.12 External Independent Burst Triggering
Since the delta-sigma conversion process is essentially continuous, an acquisition 'burst' is
initiated by clearing the input buffer when a burst trigger occurs, and allowing subsequent 'burst'
data to accumulate in the buffer. The External Independent Burst Triggering feature allows a
burst to be initiated externally through the AUX I/O pins in the system I/O connector, regardless
of the selected rate assignment (Paragraph 3.6.1.2).
This feature is available with firmware revision 502h (Table 3.11.1) and subsequent 5XXh
revisions.
The External Burst Triggering feature is implemented as follows:
When ARM EXTERNAL TRIGGER is set HIGH in the BCR, the buffer is cleared and held
in this state until an external trigger occurs at the AUX INPUT HI/LO pins in the system I/O
connector. The trigger is edge-detected, and must be asserted HIGH for a minimum of
100ns in order to be acknowledged. When the trigger occurs:
1. The ARM EXTERNAL TRIGGER bit is cleared LOW in the BCR, and:
2. The buffer is enabled, and subsequent data accumulates in the buffer, beginning with
the first complete data scan after the trigger occurs.
To support daisy-chain operation of multiple boards, the AUX OUTPUT follows the AUX
INPUT, with no clocking delays introduced.
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The AUX inputs, outputs and associated digital ground (DGND) pins are located in the
system I/O connector as:
I/O Pin B1: AUX INPUT LO
I/O Pin B2: AUX INPUT HI
I/O Pin B3: DGND
I/O Pin B4: DGND
I/O Pin B5: AUX OUTPUT LO
I/O Pin B6: AUX OUTPUT HI.
