I found a python tool that allowed me to upload a sysupgrade.bin over serial that I forked here.
You will need a 3.3v FTDI to USB cable. I used a variant of this one.
I performed the upload from my Lubuntu VM, so it works inside a virtual machine on a Windows PC as well!
Below is the pinout for the Zsun.
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This is how I connected everything up.
FTDI---ZSUN
TX<--->RX
RX<--->TX
GND<--->GND
3.3v<-n/c->3.3v (do not connect 3.3v)
Once everything is connected, plug in the FTDI into the computer and connect to it.
Putty for Windows
picocom for linux. (maybe screen will work too)
Once you plug in the Zsun, you have to immediately press any key to interrupt the auto-boot and stay in U-Boot.
Once there you can close out of the terminal and follow the github instructions for uploading the image to RAM.
You will need a 3.3v FTDI to USB cable. I used a variant of this one.
I performed the upload from my Lubuntu VM, so it works inside a virtual machine on a Windows PC as well!
Below is the pinout for the Zsun.
This is how I connected everything up.
FTDI---ZSUN
TX<--->RX
RX<--->TX
GND<--->GND
3.3v<-n/c->3.3v (do not connect 3.3v)
Once everything is connected, plug in the FTDI into the computer and connect to it.
Putty for Windows
picocom for linux. (maybe screen will work too)
Once you plug in the Zsun, you have to immediately press any key to interrupt the auto-boot and stay in U-Boot.
Once there you can close out of the terminal and follow the github instructions for uploading the image to RAM.