SPI Programming Manual (G06.24+, H06.03+, J06.03+)

General SPI Programming Guidelines

SPI Programming Manual—427506-006

5-8

Writing High-Level Procedures

The SPI procedures provide basic functionality for building and decoding SPI buffers. If

your application performs some commands frequently, you might want to simplify your

programming task by writing high-level procedures that themselves call on the SPI

procedures.

High-level procedures you write can provide some of the parameters needed by the

SPI procedures, do error checking and recovery, format SPI buffers for commonly

needed commands in one procedure call, or even both format and send commonly

needed commands in a single call.

In deciding whether to write your own high-level procedures, and in determining what

functions they perform if you decide to write them, consider the tradeoff between ease

of programming and flexibility. High-level procedures are most likely to be useful if your

application performs the same, or very similar, complex SPI buffer operations

repeatedly.

As part of EMS, HP provides two sets of high-level procedures for use in formatting

and decoding event-message buffers. For more information about these procedures,

see the

EMS Manual

Guidelines for SPI Requesters

This overview shows what your application must do to send commands to a NonStop

Kernel subsystem and process the responses:

1. Start the appropriate management process for the subsystem, if this process is not

already running.

2. Open the subsystem manager process and do whatever else is needed to

establish communication with it, such as sending the startup message if you are

programming in TAL.

3. Initialize and build the command buffer using the SPI procedures.

4. Send the command to the subsystem.

5. Receive the response from the subsystem.

6. Extract response information from the response buffer using the SPI procedures.

7. Take any appropriate action. If necessary, go back to step 3 to build another

command buffer and repeat the cycle.

8. Close the management process.

9. Stop the management process, if necessary.