Recent Posts

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Projects, Designs, and Technical Stuff / Re: A naive question about automotive CANbus sniffing and spoofing

« Last post by ataradov on Today at 02:44:19 am »

I would say that encryption is a requirement for all new designs and major redesigns. The reason you see lack of encryption is that those cars are based on dated software that nobody wants to change.

Encryption and especially authentication is one of those things that get approval from sales and marketing people. You can look good by claiming security and the same time prevent aftermarket parts and independent repair.

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Manufacturing & Assembly / modern replacement for HP clear tubing (suggest your favorite "cable" sleeve)

« Last post by coppercone2 on Today at 02:31:13 am »

I am working on HP 6177B and holy shit the cable harness is so bad.

I am thinking its possible to replace that sticky ass clear tube with some silicone tubing. Is there anything special about it? Is it just old vinyl tubing?

Something is messed up in the cable harness I think, because the nodes are not making sense (test point 7 works but VR2, R5 and R6 are not connected to the same node  ), so I am thinking maybe its the cable harness or a fried trace on the under side. Well I do need to take it apart anyway.

What cable sleeve is the best replacement for this stuff? Digikey has alot of options. I am worried about getting something too tough. Silicone tubing came to mind but I might as well buy something from a electronics distributor.

Good balance of strength, heat resistance, longevity and ductility goes to???

I thought maybe braid but then you need heat shrink and thats even more work.


Silicone fiberglass seems like common, but it does not bend super well. Anything better?

the way this thing is wired just makes me have a core meltdown
I will probobly teflonize it, chances are the wiring will all fucking fail once the boards are moved around anyway, I know better then trying to salvage that god damn wiring unless its really clear cut as to whats wrong.


looks like my laser experiments got pushed back at least a month, if I want to do a decent job restoring this unit. Probobly should.


Althought, it might be enough to rewire with teflon, zip tie it, and just skip the sleeve. imo its only there because the wiring is low quality. but it would still be nice to know

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Projects, Designs, and Technical Stuff / Re: A naive question about automotive CANbus sniffing and spoofing

« Last post by moffy on Today at 02:21:59 am »

I have to agree with ataradov, that there is a lot of verification and encryption taking place in modern cars but the degree would vary from manufacturer to manufacturer with my opinion being that the european makes e.g. mercedes, bmw etc. would be the worst. If at all possible it would be expensive and time consuming, just not practical for a one off. But I did find a link:
https://www.csselectronics.com/pages/can-bus-sniffer-reverse-engineering
might be of assistance.

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Projects, Designs, and Technical Stuff / Re: Homebrew Lock-In Amplifier

« Last post by gnuarm on Today at 02:20:47 am »

I have done photo-acoustic detection of light: so use a microphone to detect the pressure rise from modulated light to heat up some gas (e.g. water wapor to absorb 950 nm) or solid surface.

So, what were you using this for?

Many years ago, I did a bit of work with photo-acoustic signal collection.  We were using it to obtain spectra from samples that could not be put into solution so easily.  We used a rotating disc with slots cut evenly, to produce a modulated light beam.  Then the wavelength of the light was varied to produce a scan.  The AC component of the signal gave us the amplitude of the absorbance of the sample. 

Is this anything like what you were doing?  Back in '75, this was pretty virgin territory.

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Projects, Designs, and Technical Stuff / Re: A naive question about automotive CANbus sniffing and spoofing

« Last post by ataradov on Today at 02:14:17 am »

For modern cars it is virtually impossible. Your first issue would be finding all the relevant CAN buses. There are more than one, and the one you get on the OBD II port is not likely to have messages from the A/C controls. It will have some diagnostic messages, but it will not likely to accept control stuff from the outside device.

Then all the messages are now encrypted. This varies from car to car, and cars based on the older designs may still use raw messages, all new designs will use encryption and authentication.

And just figuring out the data format is not going to be trivial.

And then on top of that there may be legal issues and insuring or getting a payout for such car may be impossible.

And often those in-cabin controls are on a LIN bus or other simpler interfaces like this. So, you would need to do quite a bit of reverse engineering.

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Beginners / Re: 5V buck converter debugging

« Last post by davegravy on Today at 02:06:07 am »

Ignore that the schematic says LM63460, this is the LM64460, specifically the non-adjustable 5V output model.

Well I decided to replace the chip anyways and this time current limit my bench supply to 100mA. My bench supply is outputting 3.8V @ 100mA, and the buck converter output is 1.6V.  I'm guessing I shouldn't expect that much current with no load, even though I'm not operating anywhere near my design input voltage (12V).

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Beginners / Re: How Can I check Horizontal output transistor with lcr-t4 meter?

« Last post by vk6zgo on Today at 02:05:44 am »

Analog meter and DMM are quite different things when it comes to meter resistance of sonethig, that much more nonlinear than plain resistor. And transistor (especially high voltage) definitely not a simple resistor. So experience with analog meter could be not relevant to DMM one

Analog meters typically use higher test voltages on the resistance ranges than DMMs & are capable of turning transistor junctions on.
In normal probing of circuitry, this is a disadvantage, so the DMMs are designed to not turn them on, by using a lower test voltages.

This necessitates a special "diode test" setting on the DMM (sometimes combined with the "continuity" function, as with my Fluke 77.

The "spitty finger" trick always works, except as previously noted, when the device is a bit lacking in gain, as can happen with power devices.
In that instance, a more formal biasing resistor does the trick.

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Projects, Designs, and Technical Stuff / A naive question about automotive CANbus sniffing and spoofing

« Last post by mark03 on Today at 01:56:22 am »

Some background:  My wife and I are in the market for a car, possibly a Subaru Outback.  We'd be happy buying used, especially if we could obtain one of the elusive manual transmissions which are very hard to find now in the US.  But the used market is still weird, and buying new may be a better value.  We've test-driven the 2024 Outback and mostly like it, but the "infotainment" system is a potential show-stopper for us.  Subaru have moved to an 11" touchscreen with fairly limited tactile controls.  In particular, most of the climate controls are touchscreen only.

Apart from the obvious stupidity of driver-operated touchscreen controls, we both feel like the infotainment could be an expensive time bomb.  We try to drive our cars into the ground, at least 300,000 km and hopefully longer.  What happens 15-20 years down the road when something in the infotainment gives out?  We can live without a radio, but not without heat/AC.  This touchscreen madness is infecting multiple car brands and increasingly hard to avoid.

Thus my CANbus question.  I have plenty of experience in embedded HW/SW development but I haven't yet played with CAN.  How feasible is it to set up a sniffer, eavesdrop on the bus while changing controls like the vent configuration, and pick out the corresponding CAN ID and message?  Then, in the doomsday scenario of an uneconomical infotainment repair, just replace the stupid thing with a 3D-printed panel and some knobs connected to my own STM32 board which sends the appropriate CAN messages?

I'm hoping somebody with actual experience playing with this stuff can point out the flaws in my plan, possible roadblocks, etc.  I don't see aftermarket controls for modern cars, so either I'm not looking hard enough or it's more difficult to reverse engineer and spoof them than I thought.

Mark

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Repair / Re: Trying to troubleshoot a main board with Rockchip RK3288 microprocessor

« Last post by tbegal on Today at 01:54:43 am »

300mb Firmware file?

They 60mb....

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Repair / Re: Please help to identify component

« Last post by floobydust on Today at 01:28:11 am »

Welcome to the forums
I find SMD marking "71A" QFN-8 package is RT8297 buck converter.