本节介绍在录音路径上实现辅助 ASI 混频器的示例。以下示例代码是在 TAC5112EVM-K 评估模块上使用 PurePath™ Console 3 执行测试。该测试为混频器提供 4 个数字输入：

1. 在 PASI_RX_CH1 上输入频率为 1.5kHz、0.4FS（满标度）的数字正弦波信号，采样率为 48kHz。
2. 在 PASI_RX_CH2 上输入频率为 3.3kHz、0.4FS（满标度）的数字正弦波信号，采样率为 48kHz。
3. 在 SASI_RX_CH1 上输入频率为 100Hz、0.5FS（满标度）的数字正弦波信号，采样率为 16kHz。
4. 在 SASI_RX_CH2 上输入频率为 900Hz、0.6FS（满标度）的数字正弦波信号，采样率为 16kHz。

该器件按以下方式输出 4 个混合信号：

1. 回放信号链的 CH1 和 CH2 分别通过 DAC 路由至 OUT1P/M 和 OUT2P/M 模拟输出。
2. 回放信号链的 CH3 和 CH4 被环回到主 ASI 总线的 DOUT（PASI TX 通道 5 和通道 6）。

由于 PASI 总线以 48kHz 的频率运行，而 SASI 总线以 16kHz 的频率运行，且 SRC 处于启用状态，则 PASI 被视为主 ASI 总线，而 SASI 被视为辅助 ASI 总线。

图 3-5 所示为相关结果。

w a0 00 00 #Page 0
w a0 01 01 #SW Reset
d 01

w a0 00 00 #Page 0
w a0 02 09 #Exit Sleep Mode with DREG and VREF Enabled
d 10
w a0 1a 30 #PASI in TDM protocol with 32-bit word length
w a0 64 20 #DAC Channel 1 configured for differential output with 0.6*Vref as common mode
w a0 65 20 #DAC OUT1P configured for line out driver and audio bandwidth
w a0 66 20 #DAC OUT1M configured for line out driver and audio bandwidth
w a0 6b 20 #DAC Channel 2 configured for differential output with 0.6*Vref as common mode
w a0 6c 20 #DAC OUT2P configured for line out driver and audio bandwidth
w a0 6d 20 #DAC OUT2M configured for line out driver and audio bandwidth



w a0 0a 10 #Configure GPIO1 as GPI
w a0 0b 10 #Configure GPIO2 as GPI
w a0 0c 71 #Configure GPIO3 as SASI DOUT
w a0 0d 02 #Configure GPI1 as GPI
w a0 11 94 #Configure GPIO1 as SASI FSYNC, GPIO2 as SASI BCLK
w a0 12 60 #Select GPI1 as SASI DIN
w a0 18 00 #Enable SASI


w a0 22 24 #PASI TX CH5 to DAC Loopback CH1
w a0 23 25 #PASI TX CH6 to DAC Loopback CH2

w a0 26 01 #RX Offset = 1
w a0 28 20 #PASI RX CH1 to DAC CH1
w a0 29 21 #PASI RX CH2 to DAC CH2

w a0 00 03 #Page 3
w a0 28 20 #SASI RX CH1 to DAC CH1
w a0 29 21 #SASI RX CH2 to DAC CH2


w a0 00 01 #Page 1
w a0 17 80 #Enable SRC
w a0 2c 80 #Enable DAC ASI Mixer

#DAC AUX Mixer Inputs
#IN1 = Main ASI IN1 - 1.5kHz, 0.4FS signal tone (0.4FS)
#IN2 = Main ASI IN2 - 3.3kHz, 0.4FS signal tone (0.4FS)
#IN3 = Aux ASI IN1 - 100Hz, 0.5FS signal tone (0.4FS)
#IN4 = Aux ASI IN2 - 900Hz, 0.6FS signal tone (0.4FS)

#DAC Signal Chain OUT1 =  0.5*IN1 + 0.25*IN2 + 0.2*IN3 + 0.33*IN4
#DAC Signal Chain OUT2 =  0.2*IN1 + 0.5*IN2 + 0.4*IN3 + 0.5*IN4
#DAC Signal Chain OUT3 =  0.8*IN2 + 1.1*IN3
#DAC Signal Chain OUT4 =  1.25*IN1 + 0.5*IN4

w a0 00 11 #Page 17
#Main ASI Mixer Coefficients
w a0 08 0c cd 20 00 #a1 = 0.5, a2 = 0.2
w a0 0c 50 00 00 00 #a3 = 0, a4 = 1.25
w a0 10 20 00 10 00 #b1 = 0.25, b2 = 0.5
w a0 14 00 00 33 33 #b3 = 0.8, b4 = 0
w a0 18 00 00 00 00 #c1 = 0, c2 = 0
w a0 1c 00 00 00 00 #c3 = 0, c4 = 0
w a0 20 00 00 00 00 #d1 = 0, d2 = 0
w a0 24 00 00 00 00 #d3 = 0, d4 = 0


#Aux ASI Mixer Coefficients
w a0 48 19 9a 0c cd #a1 = 0.2, a2 = 0.4
w a0 4c 00 00 46 66 #a3 = 1.1, a4 = 0
w a0 50 20 00 15 1f #b1 = 0.33, b2 = 0.5
w a0 54 20 00 00 00 #b3 = 0, b4 = 0.5



w a0 00 00 #Page 0
w a0 76 0f #DAC Channels 1-4 enabled
w a0 78 40 #DAC Powered Up