Cirrus Logic CS8415A - Manual (Page 40)

40 DS470F4
CS8415A
One-byte mode saves the user substantial control port access time, as it effectively accesses 2 bytes worth
of information in 1 byte's worth of access time. If the control port's autoincrement addressing is used in com-
bination with this mode, multi-byte accesses such as full-block reads can be done especially efficiently.
14.2.3.2 Two-Byte Mode
There are those applications in which the A and B channel status blocks will not be the same, and the user
is interested in accessing both blocks. In these situations, two-byte mode should be used to access the E
buffer.
In this mode, a read will cause the CS8415A to output two bytes from its control port. The first byte out will
represent the A channel status data, and the 2nd byte will represent the B channel status data.
14.3 AES3 User (U) Bit Management
Entire blocks of U data are buffered using a cascade of 2 block-sized RAMs to perform the buffering. The
user has access to the second of these buffers, denoted the E buffer, through the control port. The U buffer
access only operates in two-byte mode, since there is no concept of A and B blocks for user data. The ar-
rangement of the data is as followings: Bit15[A7]Bit14[B7]Bit13[A6]Bit12[B6]...Bit1[A0]Bit0[B0]. The ar-
rangement of the data in the each byte is that the MSB is the first received bit and is the first transmitted bit.
The first byte read is the first byte received, and the first byte sent is the first byte transmitted. If you read
two bytes from the E buffer, you will get the following arrangement: A[7]B[7]A[6]B[6]....A[0]B[0].