On Sun, 1 Nov 2015 20:17:23 -0700, you wrote: >Yeah, thanks. I always forget about the distance factor. It's a shame that >I2C is so "slow" though. ~400Khz is it's max speed right ?
There's a 1.5 Mhz implementation that's out there, and I think one that's a bit faster. The processors probably support at least 400 Khz, perhaps the 1.5 Mhz. Consider, though, that this is not all that bad, it depends on the message length. 4 bytes at 9 bits/byte, that's 11,000 such messages/second (very roughly). If you're doing high level commands, that's not bad. Look up the speed of wireless transfers, for instance. Not all that much more for the "inexpensive" methods. Harvey > >On Sun, Nov 1, 2015 at 8:00 PM, Harvey White <[email protected]> wrote: > >> On Sun, 1 Nov 2015 19:32:56 -0700, you wrote: >> >> >By the way, that's an honest to god question. I see people use I2C all the >> >time, and I do not know why. From a software developer's perspective, I'm >> >often in the frame of mind that "faster is better". I kind of feel like >> >I'm missing something though. >> >> Maybe. From the hardware developer's perspective it's often a matter >> of how much additional circuitry it takes as well and how expandable >> it is. >> > >> >I do know that some parts only come in I2C, UART, or SPI. Sometimes two of >> >these serial types, but usually not all 3. So I've always assumed, that >> >people pick a part they like, and deal with the serial protocol as needed. >> >> Sometimes, yes. Lots of times it's also a question of what do you >> have that's implemented already. I have system level SPI and I2C >> implemented, so I use (more or less) what I need when I need it. >> >> Controlling a graphics chip...? (Epson S1D13781)... faster is better, >> no I2C interface at all. >> >> Putting a console interface on something that has a standard I2C >> interface on it but no SPI? I2C to UART bridge and thence to USB. >> Inexpensive addon... >> >> Processor expansion memory... RAM... acts somewhat like an external >> disk drive and *not* in program or data space.... SPI. >> >> Thermometer, LED controller, smart keyboard, smart power supply, use >> I2C. >> >> SD card, graphics chip, OLED display, TFT color display, large flash >> memory? SPI, even if you could use I2C. If the distance is short >> enough for the lines (2 inches or so), then definitely SPI. >> >> Harvey >> >> >> > >> >On Sun, Nov 1, 2015 at 6:18 PM, William Hermans <[email protected]> >> wrote: >> > >> >> I am curious though. So keep in mind I'm not so much of an EE type when >> I >> >> ask this. But why would you use I2C over another serial communications >> type >> >> ? I've used SPI on the msp430's before, and know that if one were to use >> >> SPI through the PRU's on the BBB, it would / could be amazingly fast. >> >> >> >> Is this just some sort of "x.y.z only comes in I2C peripheral . . . " >> >> sort of deal ? >> >> >> >> On Sun, Nov 1, 2015 at 6:13 PM, Harvey White <[email protected]> >> >> wrote: >> >> >> >>> On Sun, 1 Nov 2015 17:55:19 -0700, you wrote: >> >>> >> >>> >Hi Harvey, >> >>> > >> >>> >Yeah, I'm honestly not interested in I2C, at least not yet. I was just >> >>> >trying to express that I know the register in memory layout "ok" and >> that >> >>> >the OP was not using a driver, really. >> >>> > >> >>> >Thanks for the offer though. >> >>> >> >>> >> >>> You're welcome. I use it extensively, so I can at least make some of >> >>> it work. >> >>> >> >>> Harvey >> >>> >> >>> -- >> >>> For more options, visit http://beagleboard.org/discuss >> >>> --- >> >>> You received this message because you are subscribed to the Google >> Groups >> >>> "BeagleBoard" group. >> >>> To unsubscribe from this group and stop receiving emails from it, send >> an >> >>> email to [email protected]. >> >>> For more options, visit https://groups.google.com/d/optout. >> >>> >> >> >> >> >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
