Sharing files on the Raspberry Pi Zero W

I eventually managed to find some time to continue working to my Pi-zero camera project. During initial tests I took advantage of Pi-Zero wireless interface and used “sftp" command in order to transfer files between Raspberry and desktop computer. A more suitable way of transferring files using USB, like real digital cameras, would be of course advisable.

Raspberry Pi Zero as mass storage

The Pi Zero USB port is directly connected to processor, unlike others Raspberrys using a on-board USB Hub. This, cheaper, solution means the Pi Zero can be configured to act as USB host, like a computer, or as a “USB gadget” like all cell-phones and digital cameras do. In order to activate such “USB gadget” mode some specific “dcw2” kernel modules must be enabled, in my specfic case the needed module is called “g_mass_storage”. I followed this simple guide from a Github user.

First I enabled DCW2 USB driver

echo "dtoverlay=dwc2" | sudo tee -a /boot/config.txtecho "dwc2" | sudo tee -a /etc/modules

then I created a virtual disk image to be mounted as mass storage and formatted if as a FAT32 disk.

sudo dd if=/dev/zero of=/usb-drive.img bs=1M count=1000sudo mkdosfs -F 32 /usb-drive.img

Once the Raspberry PI is conncted to a computer the mass storage can be enabledl ike this

sudo modprobe g_mass_storage file=/usb-drive.img stall=0 removable=1

and disabled with following modprobe command

sudo modprobe -r g_mass_storage

the same virtual disk can be availabe to Raspberri PI by mounting it

sudo mkdir /media/usb-drivesudo mount -o loop,rw /usb-drive.img /media/usb-drive/

of course the same virtual disk cannot be both available as mass storage drive and mounted on Raspberry at the same time, since it could lead to disk corruption. The camera software will have so to manage the switch between two modes.

New toy on the desk: Raspberry PI zero W and Raspberry Camera

Just before Christmas I have been to an electronics and surplus fair where I bought myself, among other things, a new Raspberry family “thing”. I started with a vague idea of building my very own “hackable” camera. I didn't have, and still don't, have a definitive idea of how it must be or what to do with it ... just it must be hackable i.e. I must be able to reprogram it once I need it for something else. I so bought a Raspberry Pi Zero kit, including the official withe-red case heath sink and male pin strip, and a 8 M pixel Pi Camera.

Headless installation

I'm getting quite used to prepare and install Raspberry Pi images, it's the fourth time, almost always headless. Plenty of tutorials can be found on the Internet by the way. This time is not very different apart from just one detail: I had to configure the Raspberry to connect to WIFI network from the very beginning.

So after copying the latest Raspbian image on the micro-SD card withe the usual “dd” command

sudo dd if=2017-11-29-raspbian-stretch-lite.img of=/dev/sdd

I configured Raspbian to enable SSH by default

sudo touch /media/maxx/boot/ssh

Then on the same root directory I created a “wpa_supplicant” WIFI configuration file

sudo vim.tiny /media/maxx/boot/wpa_supplicant.conf

Where I wrote down my wireless network configuration

country=ITctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdevupdate_config=1
network={ssid="WIFI"psk="secret"}

At last I powered the Raspberry Pi and scanned the WIFI network for the new entry computer.

I connected trough SSH and I went, of course, trough the usual post-installation operations like changing the Pi user password and expanding the file system to the full micro-SD extent.

Pi Camera installation

Once I verified the Raspberry was correctly working I powered it back down and connected the Pi Camera using the small flat cable also included in the Pi-Zero kit I bought.