Member #47110

Member Since: September 4, 2008

Country: France

  • The problem is that even that could run afoul of the rules - some bozo will connect a longer wire as an antenna to it and it is over the 50nW ERP that is allowed here in Europe. And you can certainly exceed 50nW even with a single transistor running from a battery, no problem at all. At least we have got the 50nW now, it used to be completely verboten before - so no FM band “bugs” or streaming music to an old car radio for us.

    If people want to experiment with radio transmission, it is better to get a HAM radio license. Even using the ISM bands may not be legal, because the equipment is not certified (obviously, when it is homebrew).

    You aren’t very likely to get caught unless e.g. neighbours complain of interference or you cause interference to some important equipment (e.g. airport, emergency services, etc.), but if you do get caught, the fines are very stiff and there may be even criminal prosecution. I don’t think it is worth having a criminal record because of a stupid learning experiment.

    Teaching people to flout the rules is just wrong. At least make them aware of the restrictions - you cannot prevent people from being stupid but you can make them not be ignorant.

  • Pete, if you are planning to make show something “FCC may not be happy about” - such as a wireless microphone - do mention the rules, please. Especially in Europe building stuff that transmits in bands like the FM radio band is pretty much verboten unless very strict power limits are followed and hefty fines are possible. I believe the US rules are more lenient, but you have also overseas viewers/customers.

  • That patch is legit - signed off by the maintainer of that subsystem. They really are that dumb.

    I don’t see it getting merged, though.

  • https://lkml.org/lkml/2014/10/23/129

    WTF: “This is definitely not targeting end users - if you’re unsure if ICs are genuine then please don’t use the drivers.”

    These guys are so full of it …

  • Actually, they don’t attempt to identify the counterfeit chips. They just blindly change the PID exploiting an implementation difference between the real and the cloned chip. The real one will ignore it as invalid, the cloned one will brick itself :(

    Really really nasty hack: https://twitter.com/marcan42/status/525202516816842752

  • That is not correct - CRC is done only by USB and the bootloader, verifying that each packet of the data is not corrupted. Which won’t protect you from e.g. failing flash. There is no “CRC after upload” and the article never said anything like that neither.

    The post-upload verification works by downloading the flash and comparing byte by byte with the original hex file. If it doesn’t match, verification error is raised. Of course, that works only if you keep that “verify” switch on.

  • Bootloader CRC won’t protect you when the chip’s flash is not erased or failing. It protects you only from data corruption in transfer (e.g. due to noise). And even that isn’t infallible - the checksumming is usually fairly rudimentary.

  • What a wonderful idea … Save a few seconds on verification and then waste hours debugging incorrectly uploaded code, chips with failing or locked/not blank flash (USB nor bootloader CRC won’t protect you from that!), corrupted uploads due to intermittent or noisy connections, etc. I have seen avrdude fail in all kinds of wonderful ways, even when using bootloaders.

    Really “worth” doing. facepalm

  • You have to open the case, find the place where the wire from the pin 18 of the HDMI connector is attached. That wire carries +5V and is used to power the DAC inside the converter. Unfortunately that pin can’t provide enough current because it is meant to power only a small I2C EEPROM in the monitor that is used for DDC, not a DAC and potentially some extra circuitry. You cut that wire and feed in an external power at that point, one of those ubiquitous USB chargers will do the job fine. The precise mod varies for each of these adapters, there are several types around on eBay and DealExtreme.

  • What about the power requirements for the HDMI->VGA converter? How much current does it try to source from the HDMI port? The power pins on HDMI are meant to supply only some I2C EEPROMs for DDC monitor identification, so they often cannot provide much current.

    E.g. Raspberry Pi can source only few milliamps tops and most such converters either simply don’t work with it or can even fry it. I had to hack a similar adapter to add external power to it to use it with the Raspberry Pi.

No public wish lists :(