12 VMIVME-1184* 32-bit Optically Isolated Change-of-State (COS) Input Board
Publication No. 500-001184-000 Rev. B.0
1 • Theory of Operation
1.1 Introduction
The board functions are broken down into six major blocks. These blocks are:
• Bus interface
• Register decoder
• Interrupt Processor (IP)
• Change-of-State (COS) logic
• Input circuits
• Counter
The bus interface contains the VMEbus interface logic, the board
ʹ
s address
decoding logic and the data steering logic. The register decoder selects which data
register (BD ID, CSR, IP or input) is used during a data transfer. The IP interface
contains the logic to control the IP, interfaces with the VMEbus and issues the
interrupt request. The COS logic controls the FIFO’s data flow, determines if a
change-of-state has occurred and whether it is deemed an event and stored. The
input circuits contain the hardware to configure the topology (the shape or type of
circuit), and their trigger thresholds.
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