I’ll soon implant a third chip to take to a security system that’s incompatible with the chips I already have. It’ll be a xEM, so I know I can reconfigure it to be compatible with that one standard. But essentially, once reconfigured, it’ll be dedicated to that.
So I’m wondering: is there a chip that can somehow detect what standard the reader is using and reconfigure itself on the fly to reply with the right modulation / protocol? Possibly in a more limited way, program it so it starts talking EM4xxx if it gets a certain signal profile and something else if it gets another? Or it could be programmed to cycle through several protocols when it’s powered on? I assume such a thing doesn’t exist, but I’m curious.
Not as a single silicon chip no… you could probably technically make an MSP430 do this if you got really tricky with bit banging… I know of someone who was able to make one power itself and respond to a 125kHz system as an EM41xx chip… but getting it to actually do processing and properly communicate is a trick because it’s not meant to be field powered in this way, so the code has to do a lot of timing tricks… and because of this I think it’s quite limited… and in the end it would be huge… so the implant that does this would need to be quite large.
Okay I thought so. Although I figured a chip similar in features and computing power to the T5577 could simply cycle through two or more configurations one after the other - e.g. try to talk EM41xx first, then reset, wait a bit and try to talk Indala, then reset, wait a bit and try to talk FDX… that sort of thing. I would think the extra logic to handle the context switching and cycling would be minimal. Then again, perhaps it would confuse too many brands of readers, or make the read time unacceptably long for the protocols that get tried last.
Anyhow, I guess this is an edge use case and that’s probably why it doesn’t exist
It really comes down to market… I’m sure if you’re working on the silicon level it could be done, but who’s going to be the market for that? Billions of silicon die are made and sold to card makers and what-not, but you could not possibly achieve that kind of volume and revenue target with such a chip… hence there is no drive to make such a thing by any of the chip makers.
The only reason the t5577 exists at all is to try to edge out all these other chip makers that are currently silo’d… you no longer find em chips in cheap prox fobs anymore… it’s the t5577… because card makers can make that chip into any sort they need. Less inventory management… need to sell 10,000 hid cards to a customer? Just program your blanks… easy!