Music Shield User Manual
3
Revision 1.1. Date: December 7, 2015. Author: W. L. Yan. Editor: Felix.
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Audio output: The I2S pins and earphone are used for audio output from VS1053. The
LEFT/RIGHT pads are used for Left/Right channel output. The GBUF pad is used for Common buffer for
headphones. The I2S output pins (LOROUT, MCLK, SCLK, SDTA) are retained on the Music shield.
Recording: MICP/MICN, the differential mic input; LINE1/LINE2, the Line-in 1/2. The mic on
Music Shield is connected to MICP/MICN and the earphone is connected to LINE2.
Note: please refer to the section
Packages and Pin Descriptions
of VS1053b datasheet.
2.2.
Serial Protocol for Serial Command Interface (SCI)
The serial bus protocol for the Serial Command Interface SCI (Chapter 8.6) 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 first. XCS should be low for the full duration of the operation.
The operation is specified by an 8-bit instruction opcode. The supported instructions are read
and write. See table below.
Instruction
Name
Opcode
Operation
READ
0b0000 0011 Read data
WRITE 0b0000 0010 Write data
SCI Read
(See the Figure 6 of VS1053b datasheet)
VS1053b registers are read from using the following sequence. First, XCS line is pulled low to
select the device. Then the READ opcode (0x3) is transmitted via the SI line followed by an 8-bit word
0
1
2
3
4
5
6
7
8
9
10 11 12 13
30 31
14 15 16 17
0
0
0
0
0
0
1
1
0
0
0
0
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
15 14
1
0
X
instruction (read)
address
data out
XCS
SCK
SI
SO
don’t care
don’t care
DREQ
execution
