Basically GM was showing error codes and real time data, voltages, dwell, fuel pressure, etc. way back when the body module computer was on the level of a really good calculator. Now with cheap sophisticated computers like you'd find in a smart phone there are no limits. But marketing drives engineering so the effort is on things that take you away from interacting with the vehicle, right up to press a button and read your Kindle during the trip.
Driving used to be fun in itself and a skill to be proud of.
The key elements in human thinking are not numbers but labels of fuzzy sets. -- L. Zadeh
I've worked with the CAN bus a little as it pertains to heavy equipment, not cars...but the thing that bends my mind about it is that the protocol specifies that you have to insert a supernumerary zero bit in spans of more than five one bits, and a one bit in spans of more than five zero bits...so an octet might well have nine bits in it, one of which should be thrown away by the receiver. Which one? Might depend on the previous octet...which also might be nine bits long.
Not only does that get really annoying to do with standard UARTS, it screws up close timing something horrible.
I understand that it's because you don't have a separate clock line, so you have to extract timing information from the data signal, and you can't get timing information from a signal that doesn't change; but boy is it frickin' inconvenient.
"But whether the Constitution really be one thing, or another, this much is certain--that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist." --Lysander Spooner, 1867
Didn't know that about CAN, never had a use for the protocol. Mostly I2C or my own asynch protocol which is the simplest possible and presently for RS-485 single master (no collision issues ). No limitations on data type and a data length byte up to 0xFF less overhead for easy buffering. Everything so far fits single master, did reserve a control byte if I need more. But shades of bit stuffing in the AX25 synch protocol when ham radio went digital. Would note that Microchip has MCUs with a CAN controller built in, others too I suppose. If it's like their I2C you just service the interrupt.
The key elements in human thinking are not numbers but labels of fuzzy sets. -- L. Zadeh
Well Mickey, I was lucky today and got to go the dealership to get my light (pic of motor) turned off. As I get a little older I forgot to put the gas cap back on when I filled up. So ran some miles saw the gascap warning, stopped and put it on. Few miles later the gas cap warning went away but the motor light came on. Waited 50 miles and still didn't go out. Too many little lights and warnings on newer autos. Whatever you do, don't get old.
Ya know, I was thinking about this 'check engine light' thread...
ya know, as irksome as they are... they sure beat the old 1970s oil light coming on...I use to call it the " your engine will seize in the next 500 yds" light...
). No limitations on data type and a data length byte up to 0xFF less overhead for easy buffering. Everything so far fits single master, did reserve a control byte if I need more. But shades of bit stuffing in the AX25 synch protocol when ham radio went digital. Would note that Microchip has MCUs with a CAN controller built in, others too I suppose. If it's like their I2C you just service the interrupt.
