CYW4343X
2
10.3 I S Interface
The CYW4343X supports an independent I2S digital audio port for high-fidelity FM audio or Bluetooth audio. The I2S interface sup-
ports both master and slave modes. The I2S signals are:
■
■
■
■
I2S Clock: I2S SCK
I2S Word Select: I2S WS
I2S Data Out: I2S SDO
I2S Data In: I2S SDI
I2S SCK and I2S WS become outputs in master mode and inputs in slave mode, while I2S SDO is always an output. The channel
word length is 16 bits and the data is justified so that the MSB of the left-channel data is aligned with the MSB of the I2S bus, per the
I2S specification. The MSB of each data word is transmitted one bit-clock cycle after the I2S WS transition, synchronous with the fall-
ing edge of the bit clock. Left-channel data is transmitted when I2S WS is low, and right-channel data is transmitted when I2S WS is
high. Data bits sent by the CYW4343X are synchronized with the falling edge of I2S_SCK and should be sampled by the receiver on
the rising edge of I2S_SSCK.
The clock rate in master mode is either of the following:
48 kHz x 32 bits per frame = 1.536 MHz
48 kHz x 50 bits per frame = 2.400 MHz
The master clock is generated from the input reference clock using an N/M clock divider.
In slave mode, clock rates up to 3.072 MHz are supported.
10.3.1 I2S Timing
Note: Timing values specified in Table 15 are relative to high and low threshold levels
Table 15. Timing for I2S Transmitters and Receivers
Transmitter
Lower LImit Upper Limit
Receiver
Lower Limit Upper Limit
Min.
Max.
Min.
Max.
Min.
Max.
Min.
Max.
Notes
Clock period T
T
–
–
–
T
–
–
–
1
tr
r
Master mode: Clock generated by transmitter or receiver.
High tHC
Low tLC
0.35T
0.35T
–
–
–
–
–
–
0.35T
0.35T
–
–
–
–
–
–
2
2
tr
tr
tr
tr
Slave mode: Clock accepted by transmitter or receiver.
High tHC
–
–
–
0.35T
0.35T
–
–
–
–
–
–
–
–
–
0.35T
0.35T
–
–
–
–
–
–
–
3
3
4
tr
tr
tr
tr
Low tLC
Rise time tRC
0.15T
tr
Transmitter
Delay tdtr
–
0
–
–
–
–
0.8T
–
–
–
–
–
–
–
–
5
4
Hold time thtr
–
Receiver
Setup time tsr
Hold time thr
–
–
–
–
–
–
–
–
–
–
0.2T
0
–
–
–
–
6
6
r
Document No. 002-14797 Rev. *H
Page 54 of 128
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