you can flash eMMC without sdcard and boot (if you messed up bootloader on eMMC)
Introduce the Radxa Zero
There is this documentation https://github.com/radxa/documentation/tree/master/rs102 that really should go on the wiki.
Its fairly easy really and you don’t need a serial console but does give you some feed back that the Zero is booting in USB mode.
Its pretty easy as ‘lsusb’ will not find it on the host computer so as said not essential.
So you can jump all the serial console and just
sudo pip3 install pyamlboot
sudo apt-get install fastboot
You prob need a linux machine and ‘sudo apt-get install python3-pip’ or use a live image off a usb stick.
You could also install python on a Windows machine but can not say how that will go but likely will work.
But by keeping the little USB boot button pressed on the back of the board when you apply power the bootloader almost instantly switches to usb mode.
You just download by, or copy and paste the url
wget https://dl.radxa.com/zero/images/loader/rz-fastboot-loader.bin
Then the command is
sudo boot-g12.py rz-fastboot-loader.bin
You can follow the top document and just wipe anything off the eMMC.
To get the Zero to load up as if its a USB stick its just a different download after a power cycle.
wget https://dl.radxa.com/zero/images/loader/rz-udisk-loader.bin
Boot into usb mode and this time
sudo boot-g12.py rz-udisk-loader.bin
Then you can flash your image just as if it was a usb stick or sd card in a reader.
Last thing
wget https://dl.radxa.com/zero/images/loader/u-boot.bin
sudo dd if=u-boot.bin of=/dev/sdx bs=512 seek=1
/dev/sdx x is whatever driver letter linux applies.
lsblk
Will list unmounted drives
Zero on Armbian test:
Just tried armbian build for zero’s , on my non eMMc boards , works OK as is .
No need for additional uboot manipulations, works straight out of the box .
I used this link:
https://dl.radxa.com/users/jack/Armbian_21.08.0-trunk_Radxa-zero_focal_current_5.10.52_minimal.img
One thing that does not work out of the box for me is the wifi . However that could be because this is a minimal install image , only 1 GB .
Best Regards
Mil
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That is weird Mil as on my eMMC 2gb insert that image and it will boot from SD rather than eMMC which is great.
In my non eMMC it still doesn’t boot though.
Wanted a lite server image anyway so that is great.
I think I like that image from what I see so far even zram makes a lot of sense with the zstd for log and a single for swap.
If there’s some still available ?
I would like buying one, trying to do a DIY handheld game console on Recalbox.
Cheers
Can you try to Wipe your eMMC first, especially the eMMC boot0 and boot1.
echo 0 > /sys/block/mmcblk1boot1/force_ro
echo 0 > /sys/block/mmcblk1boot0/force_ro
Then use dd to wipe /dev/mmcblk1
@jack Zero2GB 16GB eMMC
From my working image on the SD card of Radxa Armbian I removed the SD did the fastboot method.
fastboot erase bootloader
fastboot erase bootenv
fastboot erase 0
Put the SD card back in and now no boot.
Presume if I flashed the eMMC again it will return to when no SD boot from eMMC and with SD boot from SD.
It would seem part of the initial eMMC bootloader is needed to boot the SD?
Yeah press the USB boot button on power.
sudo boot-g12.py rz-udisk-loader.bin
wget https://dl.radxa.com/zero/images/loader/u-boot.bin
sudo dd if=u-boot.bin of=/dev/sdx bs=512 seek=1
/dev/sdx x is whatever driver letter linux applies lsblk to list
reboot with the SD card and I am back again.
Just can not work out how without a eMMC as its u-boot.bin on the eMMC that seems to be the 1st bit in the chain.
No image just bootloader so now until I flash image and bootloader again its just boot from SD via the 1st chain in eMMC.
Thx stuartiannaylor for your advice and tips 
The HyperPixel IPS is gracious but expensive, I agree. Also the the GPIO will prob. be a problem for my project in combination with the Radxa Zero (if it’s not the same as the Pi and if it’s not possible to adjust the pin configuration (software-wise) this will be a deal breaker for this screen).
There are also HDMI to TTL (40 pin) converters from Adafruit available for a custom IPS build.
problem with most screens is size though. For a reasonable screen, 3.5 inch is just a little bit to small (to detect the point and click hotspots, especially from the earlier pixelated games) for my project. But >5 inch would be to bulky for a handheld (at least for the design I have in mind). I’m also gonna test the controls. I’m planning to do a trackball as my main input device. It should be interesting to find out if this is on par with mouse control.
I’m curious on the GPIO’s for the Zero. I hope Jack and the Radxa team will mass produce their PCB’s. I’m eager to start developing for this board 
All the best and I’ll let you know how progress goes (if your interested)?
cheers, Jeroen
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Nice one MicroLinux, also your other video’s 
grts, Jeroen
I dunno if this makes any sense but the gpio doesn’t have to fit as you can just use jumper wires and cursing slightly now that I got one with a header as a 90’ right angle or even solder direct would be better.
The pin mux hoping Tom posts something as not sure about the mux as I2S and SPI seem to share some pins but not sure until published and tested.
Its another reason for hdmi as the 4" has 3.5mm audio where I2S may conflict with the SPI, so not needed?
There are some things such as if in a case not sure how you will manage to get a SD card in/out as currently there is not much flesh to grab hold of.
But I am starting to see cables and ribbon for hdmi being advantageous and also should of got the off board antenna one also.
I don’t really do and CAD/CAM for a 3D print case but was just curious on approx cost, capability and how it would fit together and may just use a usb controller for test @ 800x480.
My displays are on a slowboat from aliexpress maybe a week or so and the batteries and circuit is still to be decided.
So yeah post away prob create a retro thread and I will join in with my adventures.
I am still doing extended tests and long runs with the Zero to see how things go and see how stable things seem to be.
Thx stuartiannaylor, again for your solid tips.
I will start posting progress when the Zero is available for public.
First task will be to set out all hardware on my table and building a proof of concept (without the case).
A retro thread should be indeed a good start to kick off things.
But I think you are a little further in developing for this pcb.
As soon as I can get a hold on 1 unit I will cut in, ok?
grts, Jeroen
Hi sven (and others)…
I have a question, is it possible to play Un-epic (https://www.gog.com/game/unepic) with TwisterOS?
This distro looks super (to me) als lots of retro / dosbox options…
Just wondering about Un-Epic though (not sure X86-64 works on TwisterOS?).
Another question (if you, or someone else tested this), when using a Bluetooth gamepad (like the excellent 8bitdo M30) do you notice any lag in combination with this SBC / OS ? Or is it better to use a gamepad with RF (2.4GHz)?
grts, Jeroen
Unfortunately I am not nearly qualified to answer this, but I think there are a lot of much much more knowledgeable people in here who can surely help you out!
I’m very much interested in all case-related ideas as well, because I have yet to find a solution that will allow me to place a Radxa Zero on top/near a cable modem or UPS (which I don’t dare without a case). 
Should we expect this to be faster | same | slower running android or twisterOS for desktop experience than the same installs on a raspberry pi 4 with 8gb?
How far out are we from being able to purchase and try?
Rpi have 4 x A72 core. Which this hsce 4 x A55 cores. There is no comparison in performance but graphic performance will be better using panfrost.
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Thanks for calling out the cpu spec differences that will lead to rpi4 having better cpu performance.
On the graphic front is applying panfrost driver stack for opengl support going to make for better performance on radxa zero than rpi4 because radax has arm mali g31 mp2 that driver stack supports vs rpi4 broadcom videocore vi which is not supported by that driver stack and so no opengl support?
If you want a faster TwisterOS desktop experience, you should be looking at RockPi4B+ instead (NVMe booting w/ 1.7Gb/s reading speeds and great I/O). You will get a much faster desktop performance when OCing RockPi4B+ to 2.2Ghz/1.8Ghz that will smoke any OC’d Rpi4 8Gb running from USB3 SSD/NVMe(420Mb/s I/O bandwidth limit).
Radxa Zero is a great all-around-device with lots of potencial, but as a relatively new product, still needs some improvements/tweakings/patches on the software side, meaning it will get better in terms of general desktop performance.
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Is it a full-fledged usb interface for camera or other stuff or cutted version like in google coral board mini?
Any benchmarks or tests was done officially so far?