VS1011 Datasheet, PDF (18/43 Pages) List of Unclassifed Manufacturers – MP3 AUDIO CODEC

VLSI
Solution ^y
VS1011 PRELIMINARY
VS1011
7. SPI BUSES
Because of the 32-byte safety area, the sender may send upto 32 bytes of data at a time without checking
the status of DREQ, making controlling VS1011 easier for low-speed microcontrollers.
Note: DREQ may turn low or high at any time, even during a byte transmission. Thus, DREQ should
only be used to decide whether to send more bytes. It should not abort a byte transmission that has
already started.
7.4 Serial Protocol for Serial Command Interface (SCI)
7.4.1 General
The serial bus protocol for the Serial Command Interface SCI (Chapter 8.5) consists of an instruction
byte, address byte and one 16-bit data word. Each read or write operation can read or write a single
register. Data bits are read at the rising edge, so the user should update data at the falling edge. Bytes are
always send MSb firrst.
The operation is specified by an 8-bit instruction opcode. The supported instructions are read and write.
See table below.
Name
READ
WRITE
Instruction
Opcode Operation
0000 0011 Read data
0000 0010 Write data
Note: After sending an SCI command, it is not allowed to send SCI or SDI data for 5 microseconds.
7.4.2 SCI Read
VS1011 registers are read by the following sequence, as shown in Figure 5. First, XCS line is pulled
SI line followed by an 8-bit word address. After the address has been read in, any further data on SI is
ignored. The 16-bit data corresponding to the received address will be shifted out onto the SO line.
XCS should be driven high after data has been shifted out.
7.4.3 SCI Write
VS1011 registers are written to using the following sequence, as shown in Figure 6. First, XCS line is
pulled low to select the device. Then the WRITE opcode (0x2) is transmitted via the SI line followed by
an 8-bit word address.
After the word has been shifted in and the last clock has been sent, XCS should be pulled high to end the
WRITE sequence.
Version 0.71, 2004-07-20
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