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In order to avoid contention and/or invalid data reads, there are certain rules that
must be observed:
5 A controller must not write to any of the RAM registers when Command/Parameter
Ready is false.
6 The DSP must not write to any of the RAM registers when either
Command/Parameter Ready or Query Response Ready is true.
7 A controller must not read any of the RAM registers when Query Response Ready
is false.
8 The DSP must not read any of the RAM registers when Command/Parameter
Ready is true.
9 When writing a command together with parameter, a controller must always write
to the Command Register last.
10 When executing a command that requires it to return response data, the DSP must
set the Query Response Ready bit no later than the Command/Parameter Ready bit.
11 The DSP must not clear the Done bit while Command/Parameter Ready is true.
12 The DSP must not change the Err* bit while Done is true.
13 A controller must not regard the done bits a valid while Command/Parameter
Ready is false.
14 A controller must not regard the Err* bit as valid while Done is false.
Controller Protocol Examples
There are three basic procedures used by a controller, Write Command, Read
Response and Wait for Done. These can be combined for more complex
sequences.
Write Command
This is the procedure to send a command to the DSP.
15 Wait for Command/Parameter Ready true.
16 Write any parameters to the Parameter registers and RAM.
17 Write the command to the Command register.
Read Response
This is the procedure for reading a response to query command.
18 Wait for Query Response Ready true.
19 Read the data from the Query Response register and any additional data from the
Parameter registers and RAM.
VT1433B User's Guide
Register Definitions
A-12