CS8406 datasheet(41/43 Pages) CIRRUS

41 / 43 page

CS8406

DS580F1

If the channel status block to transmit indicates PRO mode, then the CRCC byte is automatically

calculated by the CS8406, and does not have to be written into the last byte of the block by the

host microcontroller. This is also true if the channel status data is entered serially through the

COPY/C pin when the part is in hardware mode.

15.1.2 Serial Copy Management System (SCMS)

In software mode, the CS8406 allows read/modify/write access to all the channel status bits. For

consumer mode SCMS compliance, the host microcontroller needs to manipulate the Category

Code, Copy bit and L bit appropriately.

In hardware mode, the SCMS protocol can be followed by either using the COPY and ORIG input

pins, or by using the C bit serial input pin. These options are documented in the hardware mode

section of this data sheet.

15.1.3 Channel Status Data E Buffer Access

The E buffer is organized as 24 x 16-bit words. For each word the MS Byte is the A channel data,

and the LS Byte is the B channel data (see Figure 16).

There are two methods of accessing this memory, known as one byte mode and two byte mode.

The desired mode is selected through a control register bit.

15.1.3.1 One Byte mode

In many applications, the channel status blocks for the A and B channels will be identical. In this

situation, if the user reads a byte from one of the channel's blocks, the corresponding byte for the

other channel will be the same. Similarly, if the user wrote a byte to one channel's block, it would

be necessary to write the same byte to the other block. One byte mode takes advantage of the

often identical nature of A and B channel status data.

When reading data in one byte mode, a single byte is returned, which can be from channel A or

B data, depending on a register control bit. If a write is being done, the CS8406 expects a single

E to F interrupt occurs

Optionally set E to F inhibit

If set, clear E to F inhibit

Return

Write E data

Wait for E to F transfer

Figure 17. Flowchart for Writing the E Buffer

CS8406 数据表(PDF) 41 Page - Cirrus Logic