UART has another advantage, fungible cheap very-long runs when paired to balanced RS485 transceivers–at least, for relatively slow baud rates, and with decent shielded cable, you can get 56 kbps well over a kilometer. Better with some effort.
In a past life I got a patent on a hardware product that used UARTs and cheap optical parts to do face-to-face wireless at 230K+... we did our firmware upgrades and configuration in the field (where installation environments might have dozens of our product).
I always liked I2C, though; and if I'd stayed in that industry, we were looking at CAN for fault tolerance...
OMG, I2C is... terrible, as others have commented, because a slave can hold up the bus 'forever'. Also, not frequently understood is the crappy protocol requires both CLK and DATA to be bi-directional in order to handle all the required states. Top that off with 3 different 'standard' speeds, two different addressing modes, non-standard voltages often requiring voltage translation -- I2C is just a terrible excuse for a bus. In fact, I've never met a practicing geek who likes I2C, as it's nothing but headaches dealing with the corner cases, and whacking the chips when the bus goes catatonic. Ugh. Just terrible.
And CAN? That's worse. I don't want to raise my blood pressure too much, so suffice it to say that CAN was invented in the 80s so it could be implemented with small amounts of code and fairly simple hardware because: 80s. It requires very careful planning of every message type. There is a limit to the # of messages you can have on any one bus. The bus is not one speed, could be many common speeds. It's a standard that needs to be put into the past ASAP.
What should we use instead? I3C is trying to supplant I2C, but SPI is clearly the simple, fast alternative. UARTs these days (e.g. the common CP2102) can do 3.8 Mbaud easily - that ain't too bad. And if you need anything approaching 'real networking' --- then, gosh, use Real Networking: Ethernet. Even poky 100 Mb/s 4-wire Ethernet is better than CAN.
(note: any technology can have a 'perfect' niche, so sure, in certain applications. I2C could be optimal, and so could CAN; but generally, I claim those are mostly legacy applications.)
CAN is interesting in that the protocol is pretty complex, but from software point of view it's just send_packet() and register a handler for receive packets. The annoying thing is that MCUs don't have built-in CAN line drivers.
A new thing is 1000BASE-T1- Gigabit Ethernet over a single twisted pair. This is supposed to be the future in the auto world..
Comments
UART has another advantage, fungible cheap very-long runs when paired to balanced RS485 transceivers–at least, for relatively slow baud rates, and with decent shielded cable, you can get 56 kbps well over a kilometer. Better with some effort.
In a past life I got a patent on a hardware product that used UARTs and cheap optical parts to do face-to-face wireless at 230K+... we did our firmware upgrades and configuration in the field (where installation environments might have dozens of our product).
I always liked I2C, though; and if I'd stayed in that industry, we were looking at CAN for fault tolerance...
OMG, I2C is... terrible, as others have commented, because a slave can hold up the bus 'forever'. Also, not frequently understood is the crappy protocol requires both CLK and DATA to be bi-directional in order to handle all the required states. Top that off with 3 different 'standard' speeds, two different addressing modes, non-standard voltages often requiring voltage translation -- I2C is just a terrible excuse for a bus. In fact, I've never met a practicing geek who likes I2C, as it's nothing but headaches dealing with the corner cases, and whacking the chips when the bus goes catatonic. Ugh. Just terrible.
And CAN? That's worse. I don't want to raise my blood pressure too much, so suffice it to say that CAN was invented in the 80s so it could be implemented with small amounts of code and fairly simple hardware because: 80s. It requires very careful planning of every message type. There is a limit to the # of messages you can have on any one bus. The bus is not one speed, could be many common speeds. It's a standard that needs to be put into the past ASAP.
What should we use instead? I3C is trying to supplant I2C, but SPI is clearly the simple, fast alternative. UARTs these days (e.g. the common CP2102) can do 3.8 Mbaud easily - that ain't too bad. And if you need anything approaching 'real networking' --- then, gosh, use Real Networking: Ethernet. Even poky 100 Mb/s 4-wire Ethernet is better than CAN.
(note: any technology can have a 'perfect' niche, so sure, in certain applications. I2C could be optimal, and so could CAN; but generally, I claim those are mostly legacy applications.)
I've done similar things with UARTs over long distance- I was about to write about it, but I actually have it on github:
https://github.com/jhallen/joes-sandbox/tree/master/hw/lined...
CAN is interesting in that the protocol is pretty complex, but from software point of view it's just send_packet() and register a handler for receive packets. The annoying thing is that MCUs don't have built-in CAN line drivers.
A new thing is 1000BASE-T1- Gigabit Ethernet over a single twisted pair. This is supposed to be the future in the auto world..