3 示例

DRE 默认参数对大多数应用都很有效。默认的 DRE 触发阈值为 -54dB。这为 DRE 提供了足够的余量以便对突然出现的强烈信号及时做出反应。增大 DRE 触发阈值可提高小信号性能，但会减小切换到起音周期之前的可用余量。可以通过减小起音时间来缓解该问题。本节展示了一个示例，其中设置了更高的 DRE 触发阈值并调整了时间常数以使 DRE 响应更快。

• 目标电平 = -54dB
• 最大增益 = 24dB
• 起音时间 = 0.01ms
• 释放时间 = 20ms
• 起音保持 = 0.0417ms
• 释放保持 = 20ms
• 起音迟滞 = 1dB
• 释放迟滞 = 3dB

# Key: w 98 XX YY ==> write to I2C address 0x98, to register 0xXX, data 0xYY
#               # ==> comment delimiter
#
# The following list gives an example sequence of items that must be executed in the time
# between powering the device up and reading data from the device. Note that there are 
# other valid sequences depending on which features are used.
#
# See the corresponding EVM user guide for jumper settings and audio connections.
#
# Differential 4-channel : INP1/INM1 - Ch1, INP2/INM2 - Ch2, INP3/INM3 - Ch3 and INP4/INM4 - Ch4
# FSYNC = 48 kHz (Output Data Sample Rate), BCLK = 11.2896 MHz (BCLK/FSYNC = 256)
################################################################
#
#
# Power up IOVDD and AVDD power supplies keeping SHDNZ pin voltage LOW 
# Wait for IOVDD and AVDD power supplies to settle to steady state operating voltage range.
# Release SHDNZ to HIGH.
# Wait for 1ms.
#
w 98 00 00 # Goto Page 0
w 98 02 81 # Exit Sleep mode
d 10       # Wait for 16 ms
w 98 6C 40 # Enable DRE in DSP_CFG1
w 98 3C 01 # Select DRE on Ch. 1 using CH1_CFG0
w 98 41 01 # Select DRE on Ch. 2 using CH2_CFG0
w 98 74 01 # Select DRE on Ch. 3 using CH3_CFG0
w 98 75 01 # Select DRE on Ch. 4 using CH4_CFG0
w 98 6D 4B # DRE LVL = -36 dB, DRE GAIN = 24 dB
w 98 00 05          # Goto Page 5
w 98 7C 7F B5 16 50 # DRE Release Time Alpha 
w 98 00 05          # Goto Page 6
w 98 08 00 4A E9 B0 # DRE Release Time Beta  
w 98 0C 01 50 DB 39 # DRE Attack Time Alpha 
w 98 10 7E B5 16 50 # DRE Attack Time Beta 
w 98 18 00 00 02 00 # DRE Attack Debounce 
w 98 1C 00 04 B0 00 # DRE Release Debounce 
w 98 3C 00 00 01 00 # DRE Attack Hysteresis 
w 98 34 00 00 03 00 # DRE Release Hysteresis
 
w 98 00 00 # Goto Page 0
w 98 07 30 # TDM Mode with 32 Bits/Channel
w 98 73 f0 # Enable Ch.1 - Ch.4 
w 98 74 f0 # Enable ASI Output channels
w 98 75 e0 # Power up ADC