Analog Video From an 8-Bit Microcontroller
Uncategorized
1
Posts
1
Posters
3
Views
-
Analog Video From an 8-Bit Microcontroller
Although the CRT has largely disappeared from our everyday lives, there was a decades-long timeframe when this was effectively the only display available. It’s an analog display for an analog world, and now that almost everything electronic is digital, these amazing pieces of technology are largely relegated to retro gaming and a few other niche uses. [Maurycy] has a unique CRT that’s small enough to fit in a handheld television, but since there aren’t analog TV stations anymore, he decided to build his own with nothing but an 8-bit microcontroller and a few other small parts.
The microcontroller in question is a fairly standard 8-bit AVR. These microcontrollers have one major limitation when generating the VHF and UHF radio signals needed for analog TV: their natural clock speed is much too low. The maximum output frequency of a pin on this microcontroller is only 6 MHz, and [Maurycy] needs something about two orders of magnitude faster. To solve this problem, [Maurycy] uses a quirk of the square wave generated by toggling a pin at its maximum frequency, which is that a wide range of harmonics will be generated, some of which will have a high enough frequency to be picked up on the handheld analog TV. The microcontroller is configured to use two pins. Toggling the pins into various states allows the humble AVR to generate a usable TV signal.
The scan rate for CRTs is comparably low as well. At the beginning of each frame, there’s enough processing power left on the microcontroller to play Conway’s Game of Life, which is then sent out over the airwaves to the TV. [Maurycy] notes that his harmonics-based video generation method is extremely noisy and probably wouldn’t pass FCC muster. However, the signal Power is so low that it’s unlikely to interfere with anything. If you’re curious about these unusual sideways-built CRTs, though, we recently saw someone take two apart and use them to build a CRT-based VR headset.
Gli ultimi otto messaggi ricevuti dalla Federazione
-
@hongminhee so, I guess this is true, but maybe also the craft changes?
I am old enough to remember when it was common to embed blocks of assembly language in your C code to optimize particular functions or loops. As high level languages grew, that familiarity with hardware architecture has mostly disappeared, but we've developed other skills instead.
When I read @jesse or @simon 's posts about exploring collaboration with LLMs, I see curiosity, creativity and joy in the craft.
-
Here's a weird thing I'm trying to figure out. The mobile carriers are required to report their coverage to the FCC. They send them huge maps every six months, which the FCC makes available. But, the maps are wrong, missing big chunks of areas that I know have some coverage (in a few cases because I've been there and used LTE, in other cases because I checked the coverage map on the carrier's website and it shows broader coverage). So, why are the maps they send to the FCC wrong?
-
@wifelife so true
-
@andybaio remember when Ze Frank joined Twitter and said "We should have a Color War here like at summer camp" and it burned up Twitter for like a week and a half?
-
@c420 lol
-
@andybaio I will never forget the one time I met him after he spoke at an event in Dublin and I told him Wagamama was better than any ramen in L.A (I had never been to L.A) and he immediately stopped talking to me and walked out of the bar
-
This is a damn good article, and really makes me think about where I fall on the spectrum.
I didn't have to think very hard, I side firmly with Lawson.
I firmly believe that code is a craft, and I take pride in the time spent writing the code, not just in the product itself.
I mourn the impending loss of that kind of counter-culture approach to programming. Which is ironic because I don't think it's even the mainstream way of looking at coding... most devs I know would side with Orchard. Coding is a means to an end.
-
As luck would have it, the timing didn't work your way. A re-post hit the front page: https://news.ycombinator.com/item?id=47473178
