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Notes for a wall mount mini terminal for audio applications

Feature requested by the customer

• Small Oled display 128x128 with SPI interface
• Stereo class-d output
• Two PDM microphone
• Boot from MMC0 bus (required to use both Class D audio out lines)

Wirings

Micro SD on MMC0

Place a 68k pull-up resistor on DATA 0,1,2,3 and CMD

Oled display

PDMIC

Connessioni microfono e Berta D2

CLASS D

To put inside ahb section

sdmmc0: sdio-host@a0000000 {
    bus-width = <4>;
    pinctrl-names = "default";
    no-1-8-v;
    non-removable;  
    pinctrl-0 = <&pinctrl_sdmmc0_default>;
    status = "okay";
};

sdmmc1: sdio-host@b0000000 {
    bus-width = <4>;
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_sdmmc1_default>;
};

/* Disable USB gadget to set free PA31 used by the Class-D circuitry */

usb0: gadget@300000 {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_usba_vbus>;
};

To put inside apb section

classd: classd@fc048000 {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_classd_default>;
    /*atmel,pwm-type = "diff";*/
    atmel,pwm-type = "single";
    atmel,non-overlap-time = <0>;
    status = "okay";
};

spi0: spi@f8000000 {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_spi0_default>;
    status = "okay";

    device@0 {
        rotate = <0>;
        bgr;
        fps = <30>;
        compatible = "solomon,ssd1351";
        spi-max-frequency = <20000000>;   
        reg = <0>;
        regwidth = <8>;
        buswidth = <8>;
        verbose = <3>;
        reset-gpios = <&pioA PIN_PA13 0>;
        dc-gpios = <&pioA PIN_PA12 0>;
    };
};

pdmic@f8018000 {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_pdmic_default>;
    atmel,model = "PDMIC @ RoadRunner";
    atmel,mic-min-freq = <1000000>;
    atmel,mic-max-freq = <3246000>;
    atmel,mic-offset = <0x0>;
    status = "okay";
};

To put inside pinctrl@fc038000 section

pinctrl_classd_default: classd_default {
    pinmux = <PIN_PB1__CLASSD_R0>,
         <PIN_PB2__CLASSD_R1>,
         <PIN_PB3__CLASSD_R2>,
         <PIN_PB4__CLASSD_R3>,
         <PIN_PA28__CLASSD_L0>,
         <PIN_PA29__CLASSD_L1>,
         <PIN_PA30__CLASSD_L2>,
         <PIN_PA31__CLASSD_L3>;
    bias-pull-up;
};

pinctrl_sdmmc0_default: sdmmc0_default {
    cmd_data {
        pinmux = <PIN_PA1__SDMMC0_CMD>,
             <PIN_PA2__SDMMC0_DAT0>,
             <PIN_PA3__SDMMC0_DAT1>,
             <PIN_PA4__SDMMC0_DAT2>,
             <PIN_PA5__SDMMC0_DAT3>;
        bias-disable;
    };

    ck_cd_rstn_vddsel {
        pinmux = <PIN_PA0__SDMMC0_CK>,
             <PIN_PA13__SDMMC0_CD>;
        bias-disable;
    };
};

pinctrl_pdmic_default: pdmic_default {
    pinmux = <PIN_PB26__PDMIC_DAT>,
        <PIN_PB27__PDMIC_CLK>;
    bias-disable;
};

at91bootstrap setup

Memory selection  --->  
    SD Card Configuration  ---> 
        SD Host Controller Select (On SDHC0)  --->
            (X) On SDHC0
            ( ) On SDHC1

Kernel setup

Enable Class D support

Device Drivers > 
    Sound card support > 
        Advanced Linux Sound Architecture > 
            ALSA for SoC audio support 
                <*>   SoC Audio for the Atmel System-on-Chip
                <*>     Atmel ASoC driver for boards using CLASSD

Enable the Kernel support for small TFT LCD with ILI9341 LCD Controller

Device Drivers  --->
  [*] Staging drivers  --->
    <*>   Support for small TFT LCD display modules  --->
        <*>   FB driver for the SSD1351 LCD Controller

Enable PDMIC

Device Drivers > 
    Sound card support > 
        Advanced Linux Sound Architecture > 
            ALSA for SoC audio support 
                <*>   SoC Audio for the Atmel System-on-Chip
                <*>     Atmel ASoC driver for boards using PDMIC  

User space notes

Disegnare sul display in Python direttamente sul frame buffer

Installare Pittorix

git https://github.com/robertmuth/Pytorinox.git

Installare PIL e numpy

sudo apt update
sudo apt install python3-pil
sudo apt install python3-numpy

Provare gli esempi su questa pagina:

• https://raspi.muth.org/framebuffer.html

Riproduzione video

sudo mplayer -vo fbdev watch.mov

PDMIC

sudo arecord -D hw:1,0 -d 10 -f S16_LE -c1 -r48000 p48000.wav
sudo arecord -D hw:1,0 -d 10 -f cd -c1 -r48000 p48000.wav
sudo arecord -D hw:1,0 -d 10 -f cd -c2 -r48000 p48000.wav

Class D

List the adio devices

sudo aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: CLASSD [CLASSD], device 0: CLASSD PCM atmel-classd-hifi-0 [CLASSD PCM atmel-classd-hifi-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0    

Play

sudo mplayer money.m4a 

Wolfson WM8731

• https://www.linux4sam.org/bin/view/Linux4SAM/UsingI2SC
• Wolfson WM8731 datasheet

Hardware notes

Links

Microfono ST MP34DT05-A (Scheda du valutazione ST)

• Datasheet MP34DT05-A

Microfono PDMIC WM7211 (obsoleto)

• How to use record audio stream with PDMIC Cyrrus Logic WM7211
• Datasheet WM7211

Alternativa Microfono PDMIC ST MP34DT01-M

• Datasheet
• Scheda di valutazione Adatfuit

Sergio Tanzilli
Systems designer, webmaster of www.acmesystems.it and founder of Acme Systems srl

Personal email: tanzilli@acmesystems.it
Web pages: https://www.acmesystems.it --- https://www.acmestudio.it
Github repositories: https://github.com/tanzilli --- https://github.com/acmesystems
Telegram group dedicated to the Acme Systems boards: https://t.me/acmesystemssrl

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