I 2 S A u d i o I / O C a r d
6
Rev. 0.1
Figure 5. UPIO-USB-AUDIO I/O Card Features (Back)
4.1. Microphone Input
The microphone input system on the board consists of two input paths. When SW1 is in the upper position marked
with
codec
, the microphone connects to the codec (U14). When SW1 is in the lower position, the microphone
connects to the ADC_IN1 UDP signal through a filter and gain circuit. This filter and gain circuit is biased with the
ADC_VREF UDP signal.
4.2. Codec (U14) and Headphone Jack (J9)
This codec accepts register writes over I2C using the I2C_SDA_EZR and I2C_SCL_EZR signals. The
TIMER_EX_A signal provides the clock, and I2SRX_DOUT_A and I2STX_DOUT_A are the digital audio data input
and output signals. The I2S word sync (WS) and clock (SCK) signals can source from either the I2S receiver or I2S
transmitter on the MCU card. The capacitors, resistors, microphone, and headphone jack connections surrounding
the codec are based on the manufacturer’s recommendations. Table 1 summarizes the codec connections.
Table 1. Codec Connections
Codec Signal
UDP Signal
Command I2C data
I2C_SDA_EZR
Command I2C clock
I2C_SCL_EZR
External clock
TIMER_EX_A
I2S word sync (WS)
I2STX_DFS_A and I2SRX_DFS_A
I2S clock (SCK)
I2STX_CLK_A and I2SRX_CLK_A
I2S input (to codec) data (SD) (DACDAT pin)
I2SOUT_DOUT_A
I2S output (from codec) data (SD) (ADCDAT pin)
I2SIN_DOUT_A
LCD and
Joystick MCU
EBID MCU
