31 ms·
Then surely there must be competition or a record for “tallest ever,” hopefully requiring each layer to be functional.
by arwhatever 3y ago
Then surely there must be competition or a record for “tallest ever,” hopefully requiring each layer to be functional.
- extraduder_ire 3y agoI think you can have over a hundred different i2c devices connected to the same bus, so it'd get pretty tall if you can power them all. 10-bit i2c (not very common) can do almost a thousand. Although, you'd need specific rules if you wanted to prevent someone just layering up always-on LED boards.
- dmitrygr 3y ago> you can have over a hundred different i2c devices connected to the same bus In theory sure, in a world with zero-inductance zero-capacitance busses and infinite-sink-current drivers. In our reality, however, you'll start having issues and start requiring stronger pullups and lower speeds long before you get to a hundred.
- dfox 3y agoOne pretty popular home alarm brand uses I2C as “the bus” with somewhat ridiculously large cable lengths for what was designed as a board/enclosure level cheap serial bus. It is in no way a sane design, but it seems to work.
- dmitrygr 3y agomaybe at a 100Hz clock rate?
- monocasa 3y agoThis reminds me of one of the dirtiest things I've seen in this space. Saw i2c buses bridged across multiple chassis by bridging the boards with CAN transceivers. It mostly worked, but I feel like everyone who signed off on that design review should feel bad about the atrocity they created.
- naikrovek 3y agothat doesn't change anything in this conversation, though. one can still have lots of I2C devices on one bus if they can be given unique addresses.
- dragontamer 3y agoWhat? A 100kHz I2C with a 10kOhm pullup resistor can only take like... 1nF of capacitance before it all falls apart. (Crude napkin math for RC constant equals 10uS, I'm probably off by a magnitude but I think I'm close). We're talking about the physical wire and physical electricity. Eventually, the capacitance on the wire grows such that its literally impossible for a 100kHz wave (let alone a 200kHz or 1MHz wave) to be placed upon the wire. Parasitic Capacitance is real. Each item you add in parallel to a bus will increase capacitance. -------- Each item you add in serial to a bus will increase resistance and inductance, which also slows down the speed of the bus. Once the speed drops below the specified protocol (ex: 100kHz or whatever you've chosen), it all goes to crap and no one can talk anymore. I don't quite remember the napkin-math formulas for LRC-circuits but... parasitics are hugely important and nH of inductance and nC of parasitic capacitance absolutely can be reached with just a few connectors. Honestly, I think the earlier estimate of "failing by a hundred connectors" is rather optimistic still. 100kHz I2C and 10kOhm pullup would probably fail within a dozen connectors. You can have as much addressing as you like and software going on in the background. It don't matter if your literal wires no longer work as you expect.
- ajb 3y agoNearly all I2C devices only allow you to set 1 or 2 of the address bits though.
- pclmulqdq 3y agoYeah, if you choose I2C devices randomly, I think you can expect to only get about 50-ish on a bus before you run into a collision.
- MenhirMike 3y agoSomeone needs to make a Sega 32X hat to complete the Tower of Piwer?
- benj111 3y agoMy friend had a SNES -> game genie -> (super???) Game boy adaptor stack. Unfortunately the internet wasn't available to get codes for the game genie, I'm not sure it would work anyway Edit: yes the super game boy. Can't find any codes for the super game boy. So I assume that's prevented from the way they both work.
- MenhirMike 3y agoNow I'm thinking that you could stack a Game Boy Game Genie as well. SNES => SNES Game Genie => Super Game Boy => Game Boy Game Genie => Game Boy Game. (Or even better, the Game Boy Camera or Printer)
- benj111 3y agoWell an interesting hack (of a hack) was pirated / imported games couldn't be played because they didn't have a specific chip. They did have splitters so you took the chip signal from a genuine cart, and the other game plugged in the other port. So you could have your camera and printer.