The older Raspberry Pi's (Pi 1, Pi 2 and Pi Zero) couldn't boot from a USB-device, but the Raspberry Pi 3 has support for it. The Pi and Pi 2 have semi-support for it (using an SD-card with a single bootfile). The Pi Zero W is a remake of their older boards but it's newer than the Pi 3.
Is the Raspberry Pi Zero W fully compatible with the new bootcode? Can the Raspberry Pi Zero W boot from USB without using an SD card?
EDIT: This is possible if the Zero/Zero W is set up to act as a USB device and gets the boot files from a host machine that it's plugged into. See Janghou's answer below for details.
The rest of this post applies to booting the Zero W when it is acting as a USB host, which appears to be what the original question was asking.
Not with no SD card at all. The Pi Zero W uses a BCM2835, which contains the old SD card-only bootloader. It's not so much a question of the Pi being older or newer as of which processor it uses.
Also, this thread states that they can only really give the BCM2835/BCM2836* a new bootloader if somebody is willing to donate a LOT of money to create a new mask rom that could be used to program the chips.
However, as Toothbrush pointed out in the comments, you can use an SD card with just bootcode.bin on it and you will be able to boot from a USB device.
*The now out of production BCM2836, which was used in the Pi 2 until that model switched to use the BCM2837, uses the old bootloader as well.
bootcode.bin onto the SD card, you can boot from a USB mass storage device. See github.com/raspberrypi/documentation/blob/master/hardware/… for details.
Commented
Mar 13, 2017 at 18:56
Yes
You can boot an RPI Zero without a SD card through an USB cable connected with a PC.
You need Raspberry Pi USB booting code that is available here on Github or can be installed on a RPI or Raspberry Desktop computer (PC) running Stretch.
It's available since the Stretch update of 2017-12:
sudo apt-get install usbbootgui
Just connect a RPI Zero with an USB cable in the USB OTG and without an SD card, a GUI will pop-up:
For accessing GIO pins.
Is should be possible to boot Stretch (or any other application) through USB, although I've not seen a working example yet.
A first step into booting Stretch Lite (crashes when looking for the rootfs) can be achieved with:
# setup a Loop device and scan partition table
sudo losetup -P /dev/loop0 ~/Downloads/2017-11-29-raspbian-stretch-lite.img
# if loop device busy try /dev/loop1
# mount the loop device boot partition
sudo mount /dev/loop0p1/ /media/pi/
# boot the pi zero from the mounted image
sudo rpiboot -d /media/pi/
The pi Zero will boot and show the red Raspberry Icon, but there it stops.
This blog-post describes how to boot Raspbian Stretch on a Zero without an SD card.
usbboot doesn't recognize a new device when I plug in my Zero W. Do I have to put it into device mode first? If so, is that possible without an SD card?
Commented
Mar 22, 2020 at 17:58
Simple answer is "No, and no."
Raspberry Pi Zero W was released newer than the Pi 3. But Raspberry Pi Zero W use older chip--BCM2835. It can do same thing as you mentioned--The Pi and Pi 2, and Pi Zero W have semi-support for it (using an SD-card with a single bootfile).
I appreciate all the answers but when I am reading answers it made me more confusing than what was asked--I think because I am quite beginner in the Raspberry Pi.
So I think it might helpful for beginner like me.
