audio调试：数字麦（DMIC)如何配置

科技前沿 • 2025-03-27 18:07 • 阅读 54

大家好，我是讯享网，很高兴认识大家。

本文介绍rk3588平台DMIC的配置；首先了解下，常见的数字麦有纯pdm麦和通过一些codec芯片将数字麦转换为i2s信号输入到SOC；纯pdm麦就是直接进入SOC的pdm接口，走的是PDM信号，原理图如下所示；PDM信号就是两个线，一根数据线一根时钟线。

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阵列麦是PDM麦常见的形式，如下原理图；纯pdm麦的dts配置需要使用dummy_codec，内核要打开CONFIG_SND_SOC_DUMMY_CODEC=y；dts配置可以参考如下

sound_micarray: sound-micarray { compatible = "simple-audio-card"; simple-audio-card,format = "i2s"; simple-audio-card,name = "rockchip,sound-micarray"; simple-audio-card,mclk-fs = <256>; simple-audio-card,dai-link@0 { format = "pdm"; cpu { sound-dai = <&pdm0>; }; codec { sound-dai = <&dummy_codec>; }; }; }; pdm有全映射设置，rockchip,path-map = <int int int int>,需要和硬件上接的一致。

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使用codec芯片rt5651，es7210等，接入到SOC，即数字MIC，接的引脚是codec芯片上的引脚，不是SOC的PDM；最后转换成i2s信号输入主控。以3588平台为例，数字麦的dts参考如下：

讯享网rt5651_sound: rt5651-sound { status = "okay"; compatible = "rockchip,multicodecs-card"; rockchip,card-name = "rockchip-rt5651"; hp-det-gpio = <&gpio1 RK_PC0 GPIO_ACTIVE_HIGH>; io-channels = <&saradc 3>; io-channel-names = "adc-detect"; keyup-threshold-microvolt = <>; poll-interval = <100>; rockchip,format = "i2s"; //通过i2s进入到SOC rockchip,mclk-fs = <256>; rockchip,cpu = <&i2s0_8ch>; rockchip,codec = <&rt5651>; pinctrl-names = "default"; pinctrl-0 = <&hp_det>; play-pause-key { label = "playpause"; linux,code = <KEY_PLAYPAUSE>; press-threshold-microvolt = <2000>; }; }; rt5651: rt5651@1a { status = "okay"; #sound-dai-cells = <0>; compatible = "realtek,rt5651"; reg = <0x1a>; clocks = <&cru I2S0_8CH_MCLKOUT>; clock-names = "mclk"; assigned-clocks = <&cru I2S0_8CH_MCLKOUT>; assigned-clock-rates = <>; //mclk realtek,dmic-en = "ture"; //数字麦的使能 };

声卡生成之后，就使用tinycap指定es7210或rt5651声卡进行录音，录音时用示波器测量看看7202的pdm_clk和pdm_sdi是否有波形产生。

如何兼容2个数字麦，即主板自带的一个数字麦+外接小板的数字麦；两个数字麦的clk是不一样的，所以dts怎么配置呢？在&pdm0节点把两个clk同时配置上就可以了。

pdm0: pdm@fe4b0000 { compatible = "rockchip,rk3588-pdm"; reg = <0x0 0xfe4b0000 0x0 0x1000>; clocks = <&cru MCLK_PDM0>, <&cru HCLK_PDM0>; clock-names = "pdm_clk", "pdm_hclk"; dmas = <&dmac0 4>; dma-names = "rx"; pinctrl-names = "default"; pinctrl-0 = <&pdm0m0_clk //板载数字麦时钟 &pdm0m0_clk1 //外接数字麦时钟 &pdm0m0_sdi0 &pdm0m0_sdi1 &pdm0m0_sdi2>; #sound-dai-cells = <0>; status = "disabled"; };

多个数字麦怎么录音呢？同一组pdm，录音时去设置通道就行了，直接tinycap +通道2/4/6/8。例如下面这个，硬件上看PDM_SDI0_M0接在809，PDM_SDI1_M0接在es7202，PDM_SDI2_M0接在es7202；所以总共可以录6路，使用tinycap直接录6通道就可以了，其中：

PDM_SDI0_M0管脚是0-1通道，

PDM_SDI1_M0管脚是2-3通道，

PDM_SDI2_M0管脚是4-5通道。

PDM_SDI0_M0是接在RK809上的，所以0-1通道就是它的数据。

audio调试：数字麦（DMIC)如何配置

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