VXI VT1433B - Manual (Page 187)

Wait for Done
This is the procedure to wait for command completion and check for error.
20 Wait for Command/Parameter Ready true.
21 Wait for Done true.
22 If Err* = 0 , handle error.
Complex Sequences
A robust procedure for sending a query and reading the response would look like
this:
23 Send Command.
24 Wait for Done.
25 If no error then Read Response.
Multiple commands may be sent with a test for errors at the end of the sequence.
This example sends three commands before checking for errors.
26 Send Command.
27 Send Command.
28 Send Command.
29 Wait for Done.
DSP Protocol
When a controller writes to the Command register, a DSP interrupt is generated.
When responding to this interrupt, the DSP will follow this procedure.
30 Clear the Done bit.
31 Read and decode the command from the Command register.
32 Read any parameters from the Parameter registers and RAM.
33 If a response data is required:
34 Set Command/Parameter Ready true.
35 Finish command execution.
36 If any errors are pending set Err* = 0, else set Err* = 1.
37 Set Done true.
There are two additional requirement for the DSP:
38 Once it begins processing a command interrupt, the DSP must defer processing
subsequent commands until it has finished.
39 The DSP software maintains an error(s) pending flag (and possibly and error
queue) that is set by any command decoding or execution error and cleared by
some other method such as an error query.
VT1433B User's Guide
Register Definitions
A-13