Inital commit

12 files changed, 540 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ac3e8f2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+wpa_supplicant.conf
+output
+configs/*_defconfig
diff --git a/Config.in b/Config.in
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/Config.in
diff --git a/board/common.sh b/board/common.sh
new file mode 100644
index 0000000..ecda59d
--- /dev/null
+++ b/board/common.sh
@@ -0,0 +1,8 @@
+create_missing_dir() {
+  test -d "${TARGET_DIR}/$1" || mkdir "${TARGET_DIR}/$1"
+}
+
+remove_text() {
+  echo sed --in-place "s/$2//" $1
+  sed --in-place "s/$2//" $1
+}
diff --git a/board/genimage-raspberrypi0w.cfg b/board/genimage-raspberrypi0w.cfg
new file mode 100644
index 0000000..f76256e
--- /dev/null
+++ b/board/genimage-raspberrypi0w.cfg
@@ -0,0 +1,31 @@
+image boot.vfat {
+  vfat {
+    files = {
+      "bcm2708-rpi-zero-w.dtb",
+      "rpi-firmware/bootcode.bin",
+      "rpi-firmware/cmdline.txt",
+      "rpi-firmware/config.txt",
+      "rpi-firmware/fixup.dat",
+      "rpi-firmware/start.elf",
+      "rpi-firmware/overlays",
+      "zImage"
+    }
+  }
+  size = 32M
+}
+
+image sdcard.img {
+  hdimage {
+  }
+
+  partition boot {
+    partition-type = 0xC
+    bootable = "true"
+    image = "boot.vfat"
+  }
+
+  partition rootfs {
+    partition-type = 0x83
+    image = "rootfs.ext4"
+  }
+}
diff --git a/board/genimage-raspberrypi3.cfg b/board/genimage-raspberrypi3.cfg
new file mode 100644
index 0000000..0a54724
--- /dev/null
+++ b/board/genimage-raspberrypi3.cfg
@@ -0,0 +1,33 @@
+image boot.vfat {
+  vfat {
+    files = {
+      "bcm2710-rpi-3-b.dtb",
+      "bcm2710-rpi-3-b-plus.dtb",
+      "bcm2710-rpi-cm3.dtb",
+      "rpi-firmware/bootcode.bin",
+      "rpi-firmware/cmdline.txt",
+      "rpi-firmware/config.txt",
+      "rpi-firmware/fixup.dat",
+      "rpi-firmware/start.elf",
+      "rpi-firmware/overlays",
+      "zImage"
+    }
+  }
+  size = 32M
+}
+
+image sdcard.img {
+  hdimage {
+  }
+
+  partition boot {
+    partition-type = 0xC
+    bootable = "true"
+    image = "boot.vfat"
+  }
+
+  partition rootfs {
+    partition-type = 0x83
+    image = "rootfs.ext4"
+  }
+}
diff --git a/board/post-build.sh b/board/post-build.sh
new file mode 100755
index 0000000..6b1c86c
--- /dev/null
+++ b/board/post-build.sh
@@ -0,0 +1,114 @@
+#!/bin/sh
+
+set -u
+set -e
+
+. "${BR2_EXTERNAL_PIAUDIO_PATH}/board/common.sh"
+
+# Add a console on tty1
+if [ -e ${TARGET_DIR}/etc/inittab ]; then
+    grep -qE '^tty1::' ${TARGET_DIR}/etc/inittab || \
+	sed -i '/GENERIC_SERIAL/a\
+tty1::respawn:/sbin/getty -L  tty1 0 vt100 # HDMI console' ${TARGET_DIR}/etc/inittab
+fi
+
+# Put the whole system in readonly
+sed -ie '/^\/dev\/root/ s/rw 0 1/ro 0 0/' "${TARGET_DIR}/etc/fstab"
+
+###########################
+#                         #
+#  Network configuration  #
+#                         #
+###########################
+
+# Add default wpa_supplicant.conf if it exists
+if [ -f "$BR2_EXTERNAL_PIAUDIO_PATH/wpa_supplicant.conf" ]; then
+    create_missing_dir "/etc/wpa_supplicant/"
+    cat "$BR2_EXTERNAL_PIAUDIO_PATH/wpa_supplicant.conf" > "${TARGET_DIR}/etc/wpa_supplicant/wpa_supplicant-wlan0.conf"
+
+
+    cat << __EOF__ > "${TARGET_DIR}/etc/systemd/network/wireless.network"
+[Match]
+Name=wlan0
+
+[Network]
+DHCP=yes
+__EOF__
+
+    # Create the link to interface wlan0 directly in the system configuration
+    ln -sf /usr/lib/systemd/system/wpa_supplicant@.service "${TARGET_DIR}/usr/lib/systemd/system/multi-user.target.wants/wpa_supplicant@wlan0.service"
+    
+fi
+
+##############################
+#                            #
+#  Pulseaudio configuration  #
+#                            #
+##############################
+
+# Create the directory where pulseaudio store its files and put it in tempfs
+create_missing_dir "/var/lib/pulse"
+if ! grep -qE '/var/lib/pulse' "${TARGET_DIR}/etc/fstab"; then
+    cat << __EOF__ >> "${TARGET_DIR}/etc/fstab"
+tmpfs /var/lib/pulse tmpfs rw 0 0
+__EOF__
+fi
+
+if ! grep -qE '^load-module module-native-protocol-tcp' "${TARGET_DIR}/etc/pulse/system.pa"; then
+    cat << __EOF__ >> "${TARGET_DIR}/etc/pulse/system.pa"
+load-module module-bluetooth-policy
+load-module module-bluetooth-discover
+load-module module-native-protocol-tcp auth-ip-acl=127.0.0.1;192.168.0.0/24;2a01:e35:8ac8:0e00::/64 auth-anonymous=1
+__EOF__
+fi
+
+#############################
+#                           #
+#  Bluetooth configuration  #
+#                           #
+#############################
+
+create_missing_dir "/etc/bluetooth/"
+cat << __EOF__ > "${TARGET_DIR}/etc/bluetooth/main.conf"
+[General]
+
+Class = 200428
+DiscoverableTimeout = 0
+PairableTimeout = 0
+
+[Policy]
+AutoEnable=true
+__EOF__
+
+
+cat << __EOF__ > "${TARGET_DIR}/etc/systemd/system/bt-agent.service"
+[Unit]
+Description=Bluetooth Agent
+After=bluetooth.service
+Requires=bluetooth.service
+
+[Service]
+Type=simple
+ExecStartPre=bt-adapter --set Discoverable 1
+ExecStart=bt-agent -c NoInputNoOutput
+RestartSec=5
+Restart=always
+KillSignal=SIGUSR1
+
+[Install]
+WantedBy=bluetooth.target
+__EOF__
+
+# The same for the bluetooth, as bluetoothd keep a track for each paired device
+create_missing_dir "/var/lib/bluetooth/"
+if ! grep -qE '/var/lib/bluetooth' "${TARGET_DIR}/etc/fstab"; then
+    cat << __EOF__ >> "${TARGET_DIR}/etc/fstab"
+tmpfs /var/lib/bluetooth tmpfs rw 0 0
+__EOF__
+fi
+
+
+mkdir -p "${TARGET_DIR}"/etc/systemd/system/getty.target.wants
+# Add a console on ttyAMA0 and enable auto login
+ln -sf /usr/lib/systemd/system/serial-getty@.service "${TARGET_DIR}"/etc/systemd/system/getty.target.wants/serial-getty@ttyGS0.service
+sed '/^ExecStart=/ s/-o .-p -- ..u./--skip-login --noclear --noissue --login-options "-f root"/' -i "${TARGET_DIR}"/usr/lib/systemd/system/serial-getty@.service
diff --git a/board/post-image.sh b/board/post-image.sh
new file mode 100755
index 0000000..c7cc700
--- /dev/null
+++ b/board/post-image.sh
@@ -0,0 +1,106 @@
+#!/bin/bash
+
+set -e
+
+. "${BR2_EXTERNAL_PIAUDIO_PATH}/board/common.sh"
+
+BOARD_DIR="$(dirname $0)"
+GENIMAGE_CFG="${BOARD_DIR}/genimage-${BOARDNAME}.cfg"
+GENIMAGE_TMP="${BUILD_DIR}/genimage.tmp"
+
+for arg in "$@"
+do
+	case "${arg}" in
+		--add-miniuart-bt-overlay)
+		if ! grep -qE '^dtoverlay=' "${BINARIES_DIR}/rpi-firmware/config.txt"; then
+			echo "Adding 'dtoverlay=miniuart-bt' to config.txt (fixes ttyAMA0 serial console)."
+			cat << __EOF__ >> "${BINARIES_DIR}/rpi-firmware/config.txt"
+
+# fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
+dtoverlay=miniuart-bt
+__EOF__
+		fi
+		;;
+		--aarch64)
+		# Run a 64bits kernel (armv8)
+		sed -e '/^kernel=/s,=.*,=Image,' -i "${BINARIES_DIR}/rpi-firmware/config.txt"
+		if ! grep -qE '^arm_64bit=1' "${BINARIES_DIR}/rpi-firmware/config.txt"; then
+			cat << __EOF__ >> "${BINARIES_DIR}/rpi-firmware/config.txt"
+
+# enable 64bits support
+arm_64bit=1
+__EOF__
+		fi
+		;;
+		--gpu_mem_256=*|--gpu_mem_512=*|--gpu_mem_1024=*)
+		# Set GPU memory
+		gpu_mem="${arg:2}"
+		sed -e "/^${gpu_mem%=*}=/s,=.*,=${gpu_mem##*=}," -i "${BINARIES_DIR}/rpi-firmware/config.txt"
+		;;
+
+		--configure-piaudio)
+		# Configure piaudio
+
+		# Set the bootloader delay to 0 seconds
+		if ! grep -qE '^boot_delay=0' "${BINARIES_DIR}/rpi-firmware/config.txt"; then
+			cat << __EOF__ >> "${BINARIES_DIR}/rpi-firmware/config.txt"
+boot_delay=0
+__EOF__
+		fi
+
+		# Set turbo mode for boot
+		if ! grep -qE '^initial_turbo' "${BINARIES_DIR}/rpi-firmware/config.txt"; then
+			cat << __EOF__ >> "${BINARIES_DIR}/rpi-firmware/config.txt"
+initial_turbo=10
+__EOF__
+		fi
+
+		# Inform the kernel about the filesystem and ro state
+		if ! grep -qE 'fastboot noswap ro' "${BINARIES_DIR}/rpi-firmware/cmdline.txt"; then
+			sed '/^root=/ s/$/ fastboot noswap ro/' -i "${BINARIES_DIR}/rpi-firmware/cmdline.txt"
+		fi
+
+        # Remove the serial console over the UART port and let it available for
+        # bluetooth
+        remove_text "${BINARIES_DIR}/rpi-firmware/cmdline.txt" "console=ttyAMA0,115200 " 
+
+		if ! grep -qE '^dtoverlay=dwc2' "${BINARIES_DIR}/rpi-firmware/config.txt"; then
+
+
+			cat << __EOF__ >> "${BINARIES_DIR}/rpi-firmware/config.txt"
+dtoverlay=dwc2
+
+# https://github.com/raspberrypi/firmware/tree/master/boot/overlays
+dtparam=krnbt=on
+dtparam=i2c=on
+dtparam=audio=on
+dtoverlay=allo-boss-dac-pcm512x-audio
+__EOF__
+		fi
+
+		if ! grep -qE 'modules-load=dwc2,g_serial' "${BINARIES_DIR}/rpi-firmware/cmdline.txt"; then
+			sed '/^root=/ s/$/ modules-load=dwc2,g_serial/' -i "${BINARIES_DIR}/rpi-firmware/cmdline.txt"
+		fi
+        ;;
+	esac
+
+done
+
+# Pass an empty rootpath. genimage makes a full copy of the given rootpath to
+# ${GENIMAGE_TMP}/root so passing TARGET_DIR would be a waste of time and disk
+# space. We don't rely on genimage to build the rootfs image, just to insert a
+# pre-built one in the disk image.
+
+trap 'rm -rf "${ROOTPATH_TMP}"' EXIT
+ROOTPATH_TMP="$(mktemp -d)"
+
+rm -rf "${GENIMAGE_TMP}"
+
+genimage \
+	--rootpath "${ROOTPATH_TMP}"   \
+	--tmppath "${GENIMAGE_TMP}"    \
+	--inputpath "${BINARIES_DIR}"  \
+	--outputpath "${BINARIES_DIR}" \
+	--config "${GENIMAGE_CFG}"
+
+exit $?
diff --git a/build.sh b/build.sh
new file mode 100755
index 0000000..7b61baa
--- /dev/null
+++ b/build.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+usage() {
+    echo "usage: BUILDROOT_DIR=${BUILDROOT_DIR} $0 {boardname} all"
+    echo
+    echo "with boardname in"
+    echo " - raspberrypi0w"
+    echo " - raspberrypi3"
+}
+
+test -z ${BUILDROOT_DIR} && BUILDROOT_DIR=../buildroot 
+
+if [ ! -d ${BUILDROOT_DIR} ]; then
+    usage
+    echo
+    echo "Error: the path to buildroot \"${BUILDROOT_DIR}\" does not exists"
+    exit 1
+fi
+
+export BOARDNAME=$1
+
+case "$BOARDNAME" in
+  raspberrypi0w)
+  ;;
+  raspberrypi3)
+  ;;
+  *)
+    usage
+    echo
+    echo "Error: unknown card \"$1\""
+    exit 1
+  ;;
+esac
+
+# Merge custom buildroot configurations
+CONFIG_="BR2" KCONFIG_CONFIG="configs/${BOARDNAME}_defconfig" "$BUILDROOT_DIR/support/kconfig/merge_config.sh" -m -r "${BUILDROOT_DIR}/configs/${BOARDNAME}_defconfig" configs/config
+sed "1i ### DO NOT EDIT, this file was automatically generated\n" -i "configs/${BOARDNAME}_defconfig"
+
+## Create full buildroot configuration
+BR2_EXTERNAL="$(pwd)" make O="$(pwd)/output/$BOARDNAME" -C "$BUILDROOT_DIR" "${BOARDNAME}_defconfig"
+
+# Build
+BR2_EXTERNAL="$(pwd)" make O="$(pwd)/output/${BOARDNAME}" -C ${BUILDROOT_DIR} "$2"
diff --git a/configs/config b/configs/config
new file mode 100644
index 0000000..6ff77e9
--- /dev/null
+++ b/configs/config
@@ -0,0 +1,118 @@
+BR2_HAVE_DOT_CONFIG=y
+BR2_EXTERNAL_PIAUDIO_PATH="/home/sebastien/pi0/pi_audio"
+BR2_NEEDS_HOST_UTF8_LOCALE=y
+#BR2_DEFCONFIG="/home/sebastien/pi0/pi_audio/configs/raspberrypi3_defconfig"
+#BR2_SSP_NONE=y
+#BR2_RELRO_NONE=y
+BR2_FORTIFY_SOURCE_NONE=y
+BR2_TOOLCHAIN_USES_GLIBC=y
+BR2_TOOLCHAIN_BUILDROOT_GLIBC=y
+BR2_TOOLCHAIN_BUILDROOT_LIBC="glibc"
+BR2_PACKAGE_GLIBC=y
+BR2_USE_WCHAR=y
+BR2_ENABLE_LOCALE=y
+BR2_TARGET_GENERIC_HOSTNAME="piaudio"
+BR2_TARGET_GENERIC_ISSUE=""
+BR2_INIT_SYSTEMD=y
+BR2_ROOTFS_MERGED_USR=y
+
+BR2_TARGET_ENABLE_ROOT_LOGIN=y
+BR2_TARGET_GENERIC_ROOT_PASSWD="root"
+
+BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW=y
+BR2_SYSTEM_DHCP=""
+BR2_GENERATE_LOCALE=""
+BR2_TARGET_TZ_INFO=y
+BR2_TARGET_TZ_ZONELIST="default"
+BR2_TARGET_LOCALTIME="Etc/UTC"
+BR2_ROOTFS_POST_BUILD_SCRIPT="$(BR2_EXTERNAL_PIAUDIO_PATH)/board/post-build.sh"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="$(BR2_EXTERNAL_PIAUDIO_PATH)/board/post-image.sh"
+BR2_ROOTFS_POST_SCRIPT_ARGS="--configure-piaudio"
+BR2_PACKAGE_BUSYBOX_SHOW_OTHERS=y
+BR2_PACKAGE_PROVIDES_SKELETON="skeleton-init-systemd"
+BR2_PACKAGE_SKELETON_INIT_SYSTEMD=y
+BR2_PACKAGE_ALSA_UTILS=y
+BR2_PACKAGE_BLUEZ_ALSA_HCITOP=y
+BR2_PACKAGE_BLUEZ_ALSA_RFCOMM=y
+BR2_PACKAGE_PULSEAUDIO_ENABLE_ATOMIC=y
+BR2_PACKAGE_PULSEAUDIO=y
+BR2_PACKAGE_PULSEAUDIO_DAEMON=y
+BR2_PACKAGE_SOX=y
+
+BR2_PACKAGE_LIBTOOL=y
+BR2_PACKAGE_RPI_BT_FIRMWARE=y
+BR2_PACKAGE_RPI_WIFI_FIRMWARE=y
+
+BR2_PACKAGE_DBUS=y
+BR2_PACKAGE_DBUS_GLIB=y
+BR2_PACKAGE_PROVIDES_UDEV="systemd"
+
+BR2_PACKAGE_ALSA_LIB=y
+BR2_PACKAGE_ALSA_LIB_DEVDIR="/dev/snd"
+BR2_PACKAGE_ALSA_LIB_PCM_PLUGINS="all"
+BR2_PACKAGE_ALSA_LIB_CTL_PLUGINS="all"
+BR2_PACKAGE_ALSA_LIB_ALOAD=y
+BR2_PACKAGE_ALSA_LIB_MIXER=y
+BR2_PACKAGE_ALSA_LIB_PCM=y
+BR2_PACKAGE_ALSA_LIB_RAWMIDI=y
+BR2_PACKAGE_ALSA_LIB_HWDEP=y
+BR2_PACKAGE_ALSA_LIB_SEQ=y
+BR2_PACKAGE_ALSA_LIB_UCM=y
+BR2_PACKAGE_ALSA_LIB_ALISP=y
+BR2_PACKAGE_ALSA_LIB_OLD_SYMBOLS=y
+
+BR2_PACKAGE_LIBSNDFILE=y
+
+BR2_PACKAGE_SBC=y
+BR2_PACKAGE_SPEEX=y
+BR2_PACKAGE_SPEEX_ARM5E=y
+
+BR2_PACKAGE_EXPAT=y
+
+BR2_PACKAGE_LIBOGG=y
+
+BR2_PACKAGE_LIBNL=y
+
+BR2_PACKAGE_BLUEZ_TOOLS=y
+BR2_PACKAGE_BLUEZ5_UTILS=y
+BR2_PACKAGE_BLUEZ5_UTILS_TOOLS=y
+BR2_PACKAGE_BLUEZ5_UTILS_OBEX=y
+BR2_PACKAGE_BLUEZ5_UTILS_CLIENT=y
+BR2_PACKAGE_BLUEZ5_UTILS_DEPRECATED=y
+BR2_PACKAGE_BLUEZ5_UTILS_PLUGINS_AUDIO=y
+BR2_PACKAGE_BLUEZ5_UTILS_PLUGINS_NETWORK=y
+BR2_PACKAGE_DHCPCD=y
+BR2_PACKAGE_IFUPDOWN=y
+BR2_PACKAGE_IPROUTE2=y
+BR2_PACKAGE_IPTABLES=y
+
+BR2_PACKAGE_WPA_SUPPLICANT=y
+BR2_PACKAGE_WPA_SUPPLICANT_NL80211=y
+BR2_PACKAGE_WPA_SUPPLICANT_WPA3=y
+BR2_PACKAGE_WPA_SUPPLICANT_CLI=y
+BR2_PACKAGE_WPA_SUPPLICANT_CTRL_IFACE=y
+
+BR2_PACKAGE_KMOD=y
+BR2_PACKAGE_KMOD_TOOLS=y
+BR2_PACKAGE_SYSTEMD=y
+BR2_PACKAGE_SYSTEMD_PSTORE=y
+BR2_PACKAGE_SYSTEMD_HOSTNAMED=y
+BR2_PACKAGE_SYSTEMD_HWDB=y
+BR2_PACKAGE_SYSTEMD_MYHOSTNAME=y
+BR2_PACKAGE_SYSTEMD_NETWORKD=y
+BR2_PACKAGE_SYSTEMD_RESOLVED=y
+BR2_PACKAGE_SYSTEMD_TIMEDATED=y
+BR2_PACKAGE_SYSTEMD_TIMESYNCD=y
+BR2_PACKAGE_SYSTEMD_TMPFILES=y
+BR2_PACKAGE_SYSTEMD_VCONSOLE=y
+
+BR2_PACKAGE_UTIL_LINUX=y
+BR2_PACKAGE_UTIL_LINUX_LIBS=y
+BR2_PACKAGE_UTIL_LINUX_LIBBLKID=y
+BR2_PACKAGE_UTIL_LINUX_LIBMOUNT=y
+BR2_PACKAGE_UTIL_LINUX_LIBSMARTCOLS=y
+BR2_PACKAGE_UTIL_LINUX_LIBUUID=y
+BR2_PACKAGE_UTIL_LINUX_AGETTY=y
+BR2_PACKAGE_UTIL_LINUX_FSCK=y
+BR2_PACKAGE_UTIL_LINUX_MOUNT=y
+BR2_PACKAGE_UTIL_LINUX_RFKILL=y
diff --git a/external.desc b/external.desc
new file mode 100644
index 0000000..308ab7d
--- /dev/null
+++ b/external.desc
@@ -0,0 +1,2 @@
+name: PIAUDIO
+desc: Sound server
diff --git a/external.mk b/external.mk
new file mode 100644
index 0000000..a1ebada
--- /dev/null
+++ b/external.mk
@@ -0,0 +1 @@
+include $(sort $(wildcard $(BR2_EXTERNAL_PIAUDIO_PATH)/package/*/*.mk))
diff --git a/readme.rst b/readme.rst
new file mode 100644
index 0000000..c1bf677
--- /dev/null
+++ b/readme.rst
@@ -0,0 +1,82 @@
+.. -*- mode: rst -*-
+.. -*-  coding: utf-8 -*-
+
+==================================
+PIAudio : système pour raspberrypi
+==================================
+
+Ce dépôt contient la configuration buildroot permettant de construire un
+serveur de son avec un raspberrypi 0 ou raspberrypi 3.
+
+Le système ainsi créé est un système minimaliste avec un serveur pulseaudio
+ouvert sur le réseau local, et un point d’accès audio bluetooth.
+
+Installation
+============
+
+Pré-requis
+----------
+
+Il est nécessaire d’installer `buildroot`_ et créer décompresser l’archive dans
+un répertoire parent au dépôt.
+
+.. _buildroot: https://buildroot.org/
+
+Copie du dépôt
+--------------
+
+.. code-block:: bash
+
+    git clone https://git.chimrod.com/piaudio.git/
+
+Configuration
+-------------
+
+Tout est déjà configuré (ou presque…). Si l’on veut connecter la carte en wifi,
+il faut créer un fichier `wpa_supplicant.conf` dans le dépôt avec le nom du
+point d’accès et le mot de passe :
+
+::
+
+    ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
+    update_config=1
+    country=FR
+
+    network={
+            ssid=""
+            psk=""
+    }
+
+Construction
+============
+
+Lancer la commande suivante pour lancer l’image :
+
+
+.. code-block:: bash
+
+    # Construire l’image
+    ./build.sh raspberrypi0w all
+
+    # Copier sur une clef USB :
+    sudo dd if=output/raspberrypi0w/images/sdcard.img of=/dev/XXX bs=4k
+
+L’image du système est d’environ 150Mo, n’importe quel carte SD devrait
+fonctionner :)
+
+`raspberrypi0w` peut etre remplacé par `raspberrypi3` dans les commandes
+ci-dessus pour cibler cette carte.
+
+Connexion
+=========
+
+Le système est « briqué » dans le sens où il n’est pas possible de se connecter
+à distance. Par contre, avec un raspberrypi0, il est possible d’ouvrir une
+connexion locale en branchant le cable USB sur la prise USB du raspberry pi
+(pas la prise d’alimentation), et en le connectant tel quel sur l’ordinateur.
+
+On peut ensuite s’y connecter avec la commande suivante :
+
+.. code-block:: bash
+
+ screen /dev/ttyACM0