SGTL5000 audio
The ConnectCore 6 SBC assembles one NXP SGTL5000 low-power stereo codec with the following features:
- Analog inputs: line, microphone
- Analog outputs: line, headphone
- Digital I2S input/output
- Digital processing, bass, tone control, and equalizer control
The codec is a slave chip, which the CPU controls via the I2C3 port of the ConnectCore 6 system-on-chip. The CPU drives audio data through the i.MX6 Synchronous Serial Interface (SSI) port 2 using the inter-IC sound bus standard (I2S).
The Digital Audio Mux (AUDMUX) i.MX6 system-on-chip interface is a subsystem of the CPU that routes audio data from the codec into the different ports of the CPU.
Kernel configuration
You can manage the SGTL5000 audio driver support through the following kernel configuration options:
- SoC Audio for Freescale i.MX CPUs (CONFIG_SND_IMX_SOC)
- SoC Audio support for i.MX boards with sgtl5000 (SND_SOC_IMX_SGTL5000)
These options are enabled as built-in on the default ConnectCore 6 SBC kernel configuration file.
Platform driver mapping
The ALSA SoC drivers for the i.MX6 are located at:
| File | Description |
|---|---|
| sound/soc/fsl/imx-sgtl5000.c | Machine layer for the ALSA SoC layer |
| sound/soc/fsl/imx-pcm-dma.c | Platform layer for the ALSA SoC layer |
| sound/soc/fsl/imx-pcm.h | Header file for the PCM driver |
| sound/soc/fsl/fsl_ssi.c | SSI CPU Digital-Analog Interface (DAI) driver for the ALSA SoC layer |
| sound/soc/fsl/fsl_ssi.h | Header file for the SSI CPU DAI driver |
| sound/soc/codecs/sgtl5000.c | ALSA SoC codec |
| sound/soc/codecs/sgtl5000.h | ALSA SoC codec header file |
Device tree bindings and customization
The ALSA SoC system bindings are documented at:
| File | Description |
|---|---|
| Documentation/devicetree/bindings/sound/imx-audio-sgtl5000.txt | Machine layer binding |
| Documentation/devicetree/bindings/sound/imx-audmux.txt | Digital Audio Mux (AUDMUX) device bindings |
| Documentation/devicetree/bindings/sound/fsl-sai.txt | Synchronous Audio Interface (SAI) bindings |
| Documentation/devicetree/bindings/sound/fsl,ssi.txt | Synchronous Serial Interface (SSI) device bindings |
| Documentation/devicetree/bindings/sound/sgtl5000.txt | SGTL5000 Stereo Codec bindings |
The SGTL5000 audio interface is defined in the i.MX6 CPU and ConnectCore 6 SBC device tree files.
Definition of the SGTL5000 interface
ConnectCore 6 SBC device tree
sound {
compatible = "fsl,imx-audio-sgtl5000";
model = "sgtl5000-audio";
cpu-dai = <&ssi2>;
audio-codec = <&sgtl5000>;
audio-routing =
"MIC_IN", "Mic Jack",
"Mic Jack", "Mic Bias",
"Headphone Jack", "HP_OUT";
mux-int-port = <2>;
mux-ext-port = <3>;
hp-det-gpios = <&gpio2 0 0>;
hp-det-debounce = <250>;
};
SGTL5000 codec connected to I2C3 port
ConnectCore 6 SBC device tree
&i2c3 {
sgtl5000: codec@0a {
compatible = "fsl,sgtl5000";
reg = <0x0a>;
clock-frequency = <24000000>;
clocks = <&clks 201>;
VDDA-supply = <&codec_power>;
VDDIO-supply = <&codec_power>;
};
};
Definition of SSI port 2
Common i.MX6 device tree
ssi2: ssi@0202c000 {
compatible = "fsl,imx6q-ssi","fsl,imx21-ssi";
reg = <0x0202c000 0x4000>;
interrupts = <0 47 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&clks IMX6QDL_CLK_SSI2_IPG>,
<&clks IMX6QDL_CLK_SSI2>;
clock-names = "ipg", "baud";
dmas = <&sdma 41 1 0>,
<&sdma 42 1 0>;
dma-names = "rx", "tx";
fsl,fifo-depth = <15>;
fsl,ssi-dma-events = <42 41>;
status = "disabled";
};
Enabling SSI port 2
ConnectCore 6 SBC device tree
&ssi2 {
fsl,mode = "i2s-slave";
status = "okay";
};
IOMUX configuration
Digital Audio Mux (AUDMUX) IOMUX configuration:
ConnectCore 6 SBC device tree
audmux {
pinctrl_audmux: audmux {
fsl,pins = <
MX6QDL_PAD_CSI0_DAT7__AUD3_RXD 0x130b0
MX6QDL_PAD_CSI0_DAT4__AUD3_TXC 0x130b0
MX6QDL_PAD_CSI0_DAT5__AUD3_TXD 0x110b0
MX6QDL_PAD_CSI0_DAT6__AUD3_TXFS 0x130b0
>;
};
};
Power enable GPIO:
aud_pwr_en {
pinctrl_aud_pwr_en: aud_pwr_en {
fsl,pins = <
MX6QDL_PAD_EIM_OE__GPIO2_IO25 0x80000000
>;
};
};
Known issues
Headphone jack on SBCV1
On version 1 of the ConnectCore 6 SBC carrier board, quick plug/unplug of the headphone jack may induce a glitch inside the codec that can cause it to malfunction. Reset the board to restore the codec to normal functioning. Hardware in newer versions of the SBC board resolves this issue.
