Comments: Serial Communication


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  • JolyJohn / about 5 years ago * / 2

    A good run though, but I'd like to add two small items:

    • Baud is not the same as bits per second. Be aware of the difference. Baud is the number fo changes on the line per second, while bits per second is the number of bits of information transmitted. Often they are the same, but if I drove a signal line from 1 to 0 to 1 (say) 10 times per second I've had twenty changes on the line (20 baud), but I could use the precise time between those pulses, and the length of the pulses to deliver other bits of information, giving me a higher bit rate. Handy for sending higher data rates down a line with limitations. Which leads to...

    • A synchronous serial feed does not always require a seperate clock. Schemes like Manchester encoding mix the clock and the data together in such a way that you can seperate them back out again and retrieve the data relative to a steady clock. It takes more processing power, but these days that's plentiful. If you only have one path (say a laser beam) it's great way of sending data. In this sort of system baud rate is not the same as bits per second as you have transmitted every bit of the data AND the clock - more information has been sent than changes that appeared on the line.


  • Member #1686617 / about 3 years ago * / 1

    I'm a bit confused. This makes it seem like you need a UART for all serial communication ("The final piece to this serial puzzle"). Is that true? From other reading online, it seems UART is just one form of serial communication, but there is also SPI communication as well as Just trying to learn, so I figured I'd ask. I did learn quite a bit from this tutorial, so thank you!

  • I would also disagree with not seeing baud rates faster than 115.2Kbps. DMX-512A, the RS-485 serial protocol used for theatrical lighting control, runs at 250Kbps. Atmel AVR UARTs are capable of 2Mbps while some PICmicro UARTs are capable of 8Mbps.

  • Member #855703 / about 8 years ago * / 1

    ******Correction: In line>> we’re actually sending 9600 bits per second or 960 (9600/10) bytes per second. it should be 960 (9600/10) data bytes per second. right? correct me if I am wrong.

  • Member #430576 / about 8 years ago / 1

    How does this work without using CTS and RTS handshaking?

  • Member #597613 / about 9 years ago / 1

    A nice primer, was hoping to learn a bit more, but mostly it's stuff I've already dealt with.

    I would argue that RS-232 isn't nearly as unused as you imply. It gets used a lot in industrial and retail systems. For instance we have Serial connections on a large number of our machines for connecting to large scales and electronic tag readers.

  • Member #692986 / about 9 years ago / 1

    Its nice. Generally, parallel needs eight wires, one for each bit of the data so that whole 8 bits are send at the similar time. This interface utilizing 25 pin connector, & is extra of a printer version.

    You can get more information about it.

  • neumeka / about 10 years ago / 1

    This was really awesome, it cleared up so much for me in such a short amount of time. It was clear and entertaining. I loved the "cross the streams reference". :)

  • Mr Maple Man / about 10 years ago / 1

    Thanks for making this! This is the clear overview of serial communication that I've wanted for YEARS! It really helped me connect the dots and understand what is happening in serial communication. This will help me in my implementation of serial transmissions!

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