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hacking.txt
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The DSL lasercutter is a fairly generic device.
The main controller board is a "lihuiyu k40 m2 nano" and has the model number
"6c6879-LASER-M2:9" - see IMAG0006.jpg for board photo
Lots of people are talking about this board on the internet and most of them
are simply replacing it with a Smoothieboard.
It is connected to the cutter body by a flex-cable for the limit switches
and X axis motor and via a four-wire cable for the y axis. Finally, it
is connected to the power supply via a larger 4-wire molex connector,
supplying 5v and 24v (and with a signal labeled "LO" - which might be
"Laser Output")
Neither of the expansion ports or activity ports are wired up to anything.
The front panel focus adjust switch is hardwired to its motor and is
not monitorable or remote controlable in any way. The "percentage power
and test" keypad is wired directly to the PSU, also with no monitoring
or remote control.
The main chip on the controller board is labeled "lhy730318", but that
does not match any known chip.
The controller appears to have some intelligence as it does a X/Y seek
on startup - presumably reconfirming its home position (although, I have
not studied its behaviour)
There appears to be either reporting of limit switches back to the PC or
the PC sends absolute locations as the software will not let you manually
seek beyond its margins (and seems to know where these are)
The controller board is connected to the PC via a USB port, using a CH341
chip (idVendor=1a86, idProduct=5512) - this chip is visibly connected
in parallel/mem mode as you can trace the 8-bit IO lines from the CH341
to the LHY730318.
With the parallel mode, it is possible that the whole system could be run
as GPIO from the PC - the outputs needed are X-dir, X-step, Y-dir, Y-step,
Laser and inputs of Limit-X, Limit-Y. As mentioned above, it seems that
there is some intelligence in the controller, so this is less likely.
While there are open source drivers for the CH341 chip, they are all
for async serial or I2C modes - I have not been able to find a datasheet
or example code for the parallel port mode. So, the usb protocol will
need to be partially reverse engineered to find the exact data sent
Some proof-of-concept USB traces have been taken, showing it will be
possible to collect the data (and there are suggestions of a serial data
stream in them) but no correlation between the data and the PC has been
done yet.