• 07/14/2017
  • Public Content
Contents

I2S Interface

The expansion board provides one I2S port at the breakout connector to enable the connection of audio-based devices.
I2S Mapping to Breakout Connectors
Pin #
Signal Name
Direction Looking into Breakout Connector
Signal Description
J12.12
I2S_1_RXD_LS
Input
Audio data input to the expansion board, from an I2S compliant audio input device on the breakout board.
J12.14
I2S_1_TXD_LS
Output
Audio data output to an I2S compliant audio output device on the breakout board.
J12.16
I2S_1_FS_LS
Output
Audio left/right frame select signal to an I2S compliant audio device on the breakout board.
J12.18
I2S_1_CLK_LS
Input/Output
Audio bit clock output/input to an I2S compliant audio device on the breakout board.
Note:
Direction can change for slave or master mode.
I2S Level Transitions
The breakout board must include pullup resistors to the logic levels required by the audio device on the breakout board, but not to exceed 3.3 V. The pullups are from the I2S signals to a 3.3 V source. We recommend using J13 pin 6 or 8 as the 3.3 V source for the pullup resistors.
Level translation is performed by a Texas Instruments* LSF0108RKSR open drain translator.
The expansion board uses a 200 kΩ pullup resistor from the +V3P3V supply to enable EU17 when the expansion board is active.
See I2S Interface Specifications for I2S technical specifications.
Audio Signal Termination and Conditioning
For information about signal termination and conditioning, definitions of the values in the following table, and how the values were measured, refer to Termination and Conditioning. For an example of how to wire a pullup resistor for a 3.3 V pullup voltage, refer to GPIO Signal Termination and Conditioning.
SPI signal level translation termination recommendations
Signal Name
Pullup Voltage
R
min
(Ω)
CLOAD (pF)
T
rise
(ns)
T
fall
(ns)
I2S_1_CLK_LS
I2S_1_FS_LS
I2S_1_RXD_LS
I2S_1_TXD_LS
3.3
1100
47
56
17
 

Product and Performance Information

1

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