Hector Martin

uh things like the raspi dispensed with the dac and just output the pwm. again. it's easy to say impossible, doing the impossible requires a little more work. most of the time fooks scream impossible, it turns out to be a little possible.

Yes and people have turned video card VGA outputs into radio broadcasting systems. What you found in the datasheet still has *nothing* to do with any of this because it's a datasheet for a digital packet link. You might as well claim PCIe is a 2.5GHz SDR because it runs at 5Gbaud

I'm not screaming "it's impossible to broadcast RF" from a computer. Of *course* it's possible. That's what EMI *is*. That's how TEMPEST works. You can abuse interfaces for that. That doesn't change the fact that your interpretation of what you found is nonsense.

I would check schematics for long bus traces from HDA_SDOUT, other ICH10 trivia: the internal oscillator frequency is very sensitive to VccRTC variation.

Your original tweet is still nonsense because the numbers you ran are wrong and the field you found has nothing to do with the clock, it's just about framing. It's a 24MHz serial link. Period. You don't need to misinterpret errata documents for that. Read the damn HDA spec.

Nothing is "buried" in the errata doc. "oversampling" has nothing to do with any of this. You mixed up bits and bytes. That's not how oversampling works either. You're mixing up packet framing and actual bit clock frequencies. Your original tweet is 100% garbage.

If you want to research how various computer interfaces can be abused to transmit via EMI, then by all means do so, but *please please please* stop making up nonsense in your head and tweeting it to 23K followers. Do some research and come to some *actual* conclusions.

It is an interesting topic, but I'm more concerned about the hardware which is actually designed to communicate via WiFi or Bluetooth, consumer market is filled with insecure devices.