Table of Contents
Previous Chapter
Table of Contents
Previous Chapter
This section describes the preliminary design of the ACIS Back End's FEP (Front End Processor) Management software. This software is responsible for loading science code and data into the Front End Processors, issuing commands to the Front End Processors, and for acquiring data produced by the processors.
The format and content of Front End Code and Data loads are TBD. They will probably consist of a destination address, length, and data. The structure will probably contain one or more blocks, where each block has a FEP selection mask, FEP destination virtual address, the length of the load, and the data to load. The data will consist of a series of 32-bit words, formatted using little-endian byte ordering.
Figure 13 illustrates a simplified data acquisition scenario for the FEP.
FIGURE 13. FEP Management Scenario
The Back End software manages Front End commanding and data acquisition using a FEP Manager class. This class is responsible for fielding requests to the Front End Processors, and for acquiring and dispatching data produced by the Front Ends. All I/O operations to and from the Front Ends are performed via the "FEP Device" (see Table 9, "`DEA Device' Operations," on page 35). Table 31 lists the operations provided by the FEP Manager.
TABLE 31. `FEP Manager'Operations
------------------------------------------------------------------------------------------------ Function Inputs Outputs------------------------------------------------------------------------------------------------ Initialize Address of "FEP Device" to use for none input and output. TBD: If each FEP has its own device, then this should be an array of "FEP Devices," with the array index serving as the FEP Identifier. FEP Reset FEP Identifier none (Pulses the FEP's Reset line) FEP Disable FEP Identifier none (This takes the indicated FEP off-line) Write FEP Memory FEP Identifier none (Loads the FEP's FEP Address to write memory with the speci Length to write fied data) Data to write Read FEP Memory FEP Identifier Fills "Destination FEP Address to read Buffer" with the Length to Read requested FEP Data Destination Buffer Execute FEP Memory FEP Identifier Tell the FEP to call the FEP Address to Execute function located at the Reply Buffer indicated memory loca TBD: Time-out Value tion. Once the called function returns, the return value is stored in "Reply Buffer." Run FEP FEP Identifier Tell the FEP to execute FEP Address to Execute the code loaded at the specified memory loca tion. This code is expected to run until the FEP is reset. Get FEP Status FEP Identifier Reports the current state of the indicated FEP. Acquire FEP Data Destination Buffer Waits for data from any Max. Length of the running FEPs. TBD: Time-out Value Once data arrives, "Destination Buffer" is filled with the FEP gen erated information. Dump FEP Memory (TBD) FEP Identifier Acquires and teleme FEP Address to read ters the requested infor Length to Read mation from the specified FEP. Execute FEP Memory and Tele FEP Identifier Cause the FEP to call meter Reply (TBD) FEP Address to Execute the specified code, then TBD: Time-out Value wait for and telemeter the response. ------------------------------------------------------------------------------------------------
Whether or not the FEP Manager is responsible for forming the telemetry responses to "Dump Memory" and "Execute Memory" commands is TBD.
Next Chapter