An air data computer (ADC) is a crucial part of an avionics package that can calculate the altitude, vertical speed, air speed and more from pressure (via pitot tubes) and temperature inputs. When your airplane is a one-way attack drone like Iran’s Shahed-136, you obviously need an ADC as well, but have to focus on making it both cheap and circumvent a myriad of sanctions. As [Michel] recently found out while reverse-engineering one of these ADCs. Courtesy of the Russo-Ukrainian war, hundreds of these Shahed drones are being destroyed every month, with some making it back down again intact enough for some parts to end up on EBay.
The overall design as captured in the schematic is rather straightforward, with the component choice probably being the most notable, as it uses an STM32G071 MCU and Analog Devices ADM3232 RS-232 driver, in addition to the two pressure sensors (by Silicon Microstructures Inc., now owned by TE). The DC-DC converter is a Mornsun URB24055-6WR3.
With the board in working condition, [Michel] hooks it up to a test setup to see the output on the serial interface when applying different pressures to the pressure sensor inputs. This results in a lot of ASCII data being output, all containing different values that were calculated by the firmware on the STM32 MCU. In the drone this data would then be used by the flight computer to make adjustments. Overall it’s a rather basic design that doesn’t seem to have a dedicated temperature sensor either, though [Michel] is still analyzing some details. A firmware dump would of course be rather fascinating as well.
It’s not doxing when all the information is right on the data sheet. The maker of that DC-DC converter:
Mornsun Guangzhou Science & Technology Co., Ltd.
Address: No. 5, Kehui St. 1, Kehui Development Center, Science Ave., Guangzhou Science City, Huangpu District, Guangzhou, P. R. China
Tel: 86-20-38601850
Fax: 86-20-38601272
E-mail: info@mornsun.cn
http://www.mornsun-power.com
Mornsun has been on USA sanctions list since May 2024, and was removed from at least Digikey as a result. Not sure if it is related to this specific use, but wouldn’t be surprised.
Proxies and shell companies also are a thing. Wouldn’t be surprised if every controlled electronics component can still be shipped via other nations.
Remember the SPS manufacturer in Iran’s Natanz Uranium centrifuges? Won’t say which, literally first page if you google it. Doesn’t seem hard to get top notch EU components into any state.
So let’s just say sanctions are rarely helpful. They just add 1 extra step.
Nothing is hard to buy where there’s middlemen looking to profit, it’s the American dream, unfettered capitalism.
That extra step is still friction on the transactions.
Removing their US market just drives companies into other markets, ‘enemies’ of the US aren’t necessarilty everyone else’s.
Which is fine. Nobody is being forced to trade with the US. If it’s worth it to someone to trade with the bad actors instead, they can knock themselves out.
Who decides who the bad actors are ?
The board looks to be of very good quality, making me suspect that it is assembled in Shenzen and shipped to Iran and Russia. Probably a dual-use item, civilian as well as military.
Or maybe, “The board looks to be of very good quality, making me suspect that it is assembled in USA and shipped to EU/Germany. Probably a dual-use item, civilian as well as military.”
Not sure what you are trying to say, Shahed drones are not made in the EU and not used by Germany.
Iran has an electronics industry, and given the long standing policy of the Irani government to develop its military-industrial infrastructure to be as self sufficient as possible (as a result of sanctions during the Iran-Iraq War), it’s possible it was made in-house.
How are the Iranians and Russians getting hold of parts from companies like ST Microelectronics, Analog Devices and TE and why isn’t more being done to stop it?
Simple. Buy in India or Kazakhstan for example, then sell to Russia or Iran. Mind you, I’m sure perfectly functional Chinese copies also exist.
Yeah, especially the smaller STMs have been cloned up and down, there is a reason a Bluepill costs somewhere around an Euro.
Are you really surprised that smuggling is a thing? :D
In the Cold War, the US smuggled export restricted Titanium out of the Soviet Union, so why be surprised that other countries smuggle export restricted stuff as well?
You buy it from digikey using a front company in a country that has a customs union with Russia. Totally illegal of course, but it seems Russia stopped caring about international laws or even never did.
There are many US indictments against companies illegally exporting US components, semiconductors etc. also shell companies russians or chinese are running. It’s one reason for component shortages, they are of course stockpiling for their war effort.
example: https://www.justice.gov/opa/pr/businessman-arrested-scheme-illegally-export-semiconductors-and-other-controlled-technology
“and why isn’t more being done to stop it?”
You should have learned by now that stopping something is sheer infinitely harder than asking to do more to stop something. :)
I enjoyed the reverse-engineering of the board. Getting altitude, airspeed, air temperature, pretty basic IF you can buy the components… It seems to output a text string, similar to a GPS NMEA message. Not sure what the RS-232 port is needed for.
The UART won’t die, long live the UART! RS-232 levels could possibly come about due to the CCA having another primary purpose but was instead re-purposed. Another possibility is noise/ground margin(s). Yet another purpose would be if it ever was retrieved, get people fixated on asking WTF….
Ardupilot can do the same things, there is nothing difficult here.