
Rev. 2.0, 09/02, page 617 of 732
23.4.2
Communication Protocol
The AUD latches the AUDATA input when
AUDSYNC
is asserted. The following AUDATA
input format should be used.
0000
DIR
A3 to A0
A31 to A28
D3 to D0
Dn to Dn-3
Input format
Spare bits (4 bits): b'0000
Command
Fixed at 1
0: Read
1: Write
00: Byte
01: Word
10: Longword
Bit 3
Bit 2
Bit 1
Bit 0
. . . . . .
. . . . . .
Address
Data (in case of write only)
B write: n = 7
W write: n = 15
L write: n = 31
Figure 23.4 AUDATA Input Format
23.4.3
Operation
Operation starts in RAM monitor mode when
AUDRST
is asserted, AUDMD is driven high, then
AUDRST
is negated.
Figure 23.5 shows an example of a read operation, and figure 23.6 an example of a write
operation.
When
AUDSYNC
is asserted, input from the AUDATA pins begins. When a command, address,
or data (writing only) is input in the format shown in figure 23.4, execution of read/write access to
the specified address is started. During internal execution, the AUD returns Not Ready (0000).
When execution is completed, the Ready flag (0001) is returned (figures 23.5 and 23.6). Table
23.2 shows the Ready flag format.
In a read, data of the specified size is output when
AUDSYNC
is negated following detection of
this flag (figure 23.5).
If a command other than the above is input in DIR, the AUD treats this as a command error,
disables processing, and sets bit 1 in the Ready flag to 1. If a read/write operation initiated by the
command specified in DIR causes a bus error, the AUD disables processing and sets bit 2 in the
Ready flag to 1 (figure 23.7).
Bus error conditions are shown below.