User guide
Firmware Messaging
CS4953x4/CS4970x4 System Designer’s Guide
DS810UM6 Copyright 2013 Cirrus Logic, Inc 7-3
7.3.3 Solicited Read
A solicited read can be thought of as a request to read the contents of a specific register. This is
comprised of a 32-bit solicited read command word which is a request to read a specific index (register) in
a given module. The DSP, upon receiving this message, responds by sending back a 32-bit Read
Response opcode and the requested 32-bit data word contained in the register.
The following diagrams show the format of solicited Read-command word and Read-Response
Command Word message:
7.3.4 Unsolicited Read
There are times when the DSP needs to inform the host of certain changes during its operation. For
example, the DSP sending a message to the host indicating that the input stream has changed from
Dolby Digital to DTS. This information is useful to the host so it can take appropriate steps such as
downloading the correct decoder firmware module. Note that this type of message is an unsolicited
message because it was initiated by the CS4953x4/CS4970x4 rather than the host.
These messages will come from the CS4953x4/CS4970x4 to indicate a change in the system that must
be addressed. In the example used in the previous paragraph, the part is in autodetect mode and detects
a new stream. An unsolicited read message will be sent by the CS4953x4/CS4970x4 to indicate the new
stream type.
Write Data Word:
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Data [31:0]
15 14 13 12 11 10 9 8 76 5 43210
Options for Bits 23:22
23 22 Command
00Write - current value overwritten
01Write - new value OR’d with current value
10Write - new value AND’d with current value
Read-Command Word:
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
1 Module ID [6:0] 1 1 0 WordCount-1 [4:0]
Index [15:0]
15 14 13 12 11 10 9 8 76543210
Read-Response Command Word:
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
0 Module ID [6:0] 1 1 0 WordCount-1 [4:0]
Index [15:0]
15 14 13 12 11 10 9 8 76543210
Read-Response Data Word:
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0
9 8 76543210
DATA WORD[31:0]